Comparisons-study of different propulsion systems for a 4000 ton Frigate

COMPARISON

-

STUDY

OF DIFFERENT PROPULSION SYSTEMS

FOR A 4000 TON FRIGATE

VIERDE-JAARS OPDRACHT

by: K.H.E. Deleroi

student no.: 177105

july 1994

OEMO report no: 94/17

Teclmische Universiteit Delft

FOREWORD

This report is written at the company Motoren und Turbinen Union in Frieclrichshafen as the first part of a graduation work. It contains a comparison of different possible propulsion systems, using MTU and General Electric power engines, for a 4000 ton frigate.

The author is a mechanical engineering student at the Delft University of Technology, specialized in marine engineering.

I want to thank especially Prof ir. Klein Woud of the Delft University of Technology for giving me the chance to do my graduation work at MTU.

My thanks go also to Mr. Haussmann, head of the department "Einbauprojelctierung Schiff' for giving me the opportunity to work in his department and Mr. Beyerlein for his support and help.

My final thanks go to all the colleagues of the department VSM, who were helping me with this study.

Friedrichshafen, 8 july1994 K.H.E. Deleroi

comparison study of different propulsion systems for a 4000 ton frigate

TABLE OF CONTENTS

page

Summary 1

1.Introduction 2

2.Basis for the comparison 3

2.1 Description of the ship . 3

2.2 Operating profile . 4

2.3 Chosen propulsion arrangements. 6

2.4 Chosen propulsion engines 25

2.4.1 MTU diesel engine 25

2.4.2 GE gas turbine . 30

2.4.3 ICR gas turbine. 32

2.5 Gearbox and clutches 34

2.6 Ambient conditions 35

2.7 Propeller . 36

3 Propulsion plant comparison 37

3.1 Speed comparison. 37

3.1.1 Maximum speed 37

3.1.2 Cruise speed . 38

3.2 Dimensions 38

3.2.1 Dimensions of propulsion engines 39

3.2.2 Dimensions of air ducts. 40

3.3 Weight . 42

3.4 Life cycle costs ₄₃

3.4.1 First costs 43

3.4.2 Operating costs . 44

3.4.2.1 Fuel costs ₄₅

3.4.2.2 Lube oil costs. 47

3.4.2.3 Personel costs. ₄₈

3.4.2.4 Maintenance costs 48

3.4.3 Total costs ₅₀

3.5 Operating Range . ₅₂

3.6 Reliability, redundancy and manoevrability ₅₃

3.7 Infra Red Signature ₅₄

3.8 Underwater noise radiation ₆₂

3.8.1 Structure borne noise ₆₂

3.8.2 Air borne noise . 65

4. Conclusion . 67

Bibliography..

1.. . . ., . ,.. . . .

Summary

Nowadays modern frigates, with a displacement of the size of about 4000 ton, are powered by a CODOG arrangement. Due to the development of the ICR gas turbine with a better fuel

consumption, than the normally used simple cycle gas turbines and the availability of MTU diesel engines with a wide performance diagram other propulsion arrangements are possible. This report evaluates the possibility of other solutions like a CODAG or CODAD version, but also versions with the use of the ICR gas turbine.

The objective is to compare these installations on technical and economical aspects with each other. The following items are evaluated:

maximum speed cruise speed dimensions

weight of propulsion plant life cycle costs

operating range

reliability, redundancy and manoeuvrability infra red signature

under water noise radiation

All propulsion engine arrangements are satisfying the maximum speed requirement of more than 28 knots. Comparing the commonly used CODOG installation with the alternative presented propulsion plants the CODOG installation is not the best solution. The CODAG installation with a two speed gearbox and cross connection is on many aspects better, like operating costs and operating range.

But propulsion plants with an ICR gas turbine instead of simple cycle gas turbines show a better performance. These CODOG and CODAG installations have advantages concerning the operating costs, operating range and infra red intensity. The only disadvantage is that the first costs for a propulsion system with an ICR gas turbine are high.

CODAD versions are also evaluated, but great advantages comparing to the CODOG installation did not appear. The best CODAD solution would be the installation with a two speed gearbox and cross connection.

As a conclusion it can be stated that the CODOG installation with an ICR gas turbine has shown the best overall performance.

chapter 1 introduction

1. Introduction

Modern frigates with a displacement of about 4000 ton are commonly powered by a CODOG installation. Due to the development of a new kind of gasturbine, the so called ICR gasturbine, with a promising better fuel consumption and the availability of MTU diesel engines with a wide performance diagram other possibilities than the commonly used CODOG installation are now possible. It would be interesting for the engine manufactures as well as for the planning staffs of the Navy's to know, if these alternative arrangements satisfy the requirements and to know their advantages and disadvantages.

The objective of this report is to evaluate different propulsion arrangements for a modern frigate and compare them with each other.

In this comparison the technical and economical aspects of these installations are compared with each other.

Firstly the regarded ship with its operation profile and operating time is defined and the propulsion arrangements and engines are described. On this basis the performance of the installations are compared in chapter 3.

2. Basis for the comparison

For a warship it is important that the propulsion engines can fit with the operating requirements. The whole propulsion arrangement has also to be as small and light as possible, in order to have space and payload to carry as much as possible fighting and defence systems. Before beginning the comparison for the 4000 ton frigate the ship, the requirements and the assumptions for the ships duty have to be defined.

2.1 Description of the ship

In this study the propulsion systems are investigated concerninga modern Multi Purpose Warship. The choice is made, because there is now a tendency towards building naval vessels, which can be used for different purposes and in different regions. This includes anti aircraft, anti submarine, convoy and region protection and patrolling warfare.

The size of the regarded warship is:

The data of the ship are almost comparable with the German F122 frigate. The _{weight of the total} propulsion arrangement including the fuel tanks is assumed to be limited to 600 ton.

page: 3 V = 4000 t Lw

= 126.9m

Bw

= 15.7m

D

= 3.35m

CBlok = 0.58

chapter 2 basis for the comparison

The power curve of the ship is calculated with a MTU ship calculation program and is shown in figure 2.1.

POWER-CURVE

figure 2.1

2.2 Operating profile

The engagement of the Navy's was changed during the last 5 years to mainly crisis reaction missions .These activities are only multinational and world-wide imaginable. From this the following tasks for a Multi Purpose Warship are derived and each has a different influence on the machinery:

0

Anti-submarine activities 40001 CPP prcceller 126,90 m D 4,2 m 15,70m 5 biz& T 3,35 m 70% notice 2 shalt P/D 1,44 5 0 10,0 15,0 20,0 25,0 30,0 35,0

Alp peed tk.ot.1.1

45000 40000 35000 30000 F 25000 20000 15000 10000 5000 0 I I V B

attack ASW ships are commonly used for surveillance of large sea areas so the ship has to cover large operation ranges.

0

Air-defence,

'The air defence task has no direct consequence on the performance of the propulsion machinery, but an important item is the ship's infra red signature. This has to be as low as possible, so that the self guided missiles must fly for a longer time under radar guidance and can therefore be located and combated by an anti missile fighting system more easily. More details are described in chapter 4.7.

Patrolling

Patrolling is used for observing a coastal area for detecting, stopping and controlling smugglers and ships which are breaking an embargo. This task calls for operation in the low speed range but also high acceleration capability is necessary for hunting and stopping illegal ships.

Convoy and region protection

This task requires a large range with medium speed, to follow the convoy for a long time, but also quick acceleration and high speed is needed in order to interfere possible aggressors quickly.

A typical operation profile of a multi purpose warship is shown in the following figure..

operation profile of an MPNI:r

figure 2.2

The profile shown above is derived from different typical MPW ships operation profiles. It can be seen that an MPW-ship has a high percentage of use in the speed range between 10 and 19 knots

page: 5 .1-7 10-11 1243 14-13 16-17 IS-19 speed Prase.] 20-21 2243 2445 21-27 2021h

0

0

chapter 2 basis for the comparison

with a peak at 13 knots. There is also a peak at 7 knots, used when the ship is patrolling. Really high speed is not often needed. The cruising speed of these ships lies low at about 17 to 19 knots. The maximum speed of the warship should be nowadays at least 28 knots. Speeds above 30 knots are not common anymore, due to modern missile systems and the use of helicopters. High speeds require much more power of the propulsion engines which results in very large, heavy and more expensive machinery, because the output-power is a function of the speed to the third power. In addition the following assumption have to be made about the operating time and life of the ship.

mission time per year: 2000 hours life time of the ship: 25 years

That means that the ship-machinery has to be working for at least 50000 hours.

In this period the main overhaul of the gas turbines and the diesel engines should be avoided, if possible. Main overhaul of diesel engines means removal of the engines. Gas turbines only need a hot section replacement, which can be done within one day, without replacement of the whole engine.

2.3 Chosen propulsion arrangements

In this study only conventional propulsion engines like diesel engines and gas turbines are considered with a sensible division into a cruise and boost engines (exclusive the single ICR gas turbine system). The reason for this is the high specific fuel consumption of the boost engines in the low speed range. Because the low speeds predominate in the given operating profile, it makes sense to install separate engines with a better fuel consumption for the low speed regions. There are now six different solutions thinkable what is shown in the matrix.

table 2.1

The CODOD (COmbined Diesel Or Diesel) system is regarded as absurd and is neglected. This system would contain cruise diesel engines and large diesel engines for boost power. This would require large and heavy medium or slow speed diesel engines, because of the needed power of about 20000 kW per engine.

A COGAG (COmbined Gas turbine And Gas turbine) and COGOG (COmbined Gas turbine Or Gas turbine) installation are also not investigated, because of the high specific fuel consumption of these installations at the given operating profile with large parts of low speed operation, although they have attractive characteristics, such as silent operation and very flexible operational

behaviour over the complete speed range.

The ICR turbine is a new type of gas turbine design of Rolls Royce and Westinghouse and

combination same kind mixed

matrix

diesel engine gas turbine

together (AND) CODAD COGAG CODAG

separate (OR)

(CODOD)

COGOG CODOG

For survivability of the propulsion systems, regarding flooding or fire, all arrangements are considered to be separated into three watertight compartments; boost engines, cruise engines and the gearboxes.

The following propulsion systems are regarded to be realistic to be installed into a new to build 4000 ton frigate,

-2CODOG (COmbined Diesel Or Gas turbine)

225 lintin

MTU diesel engine I2V 1163 TB IC3 naa a 1250 Ihrun. CODOG plant GE gastorbee Ut42500 kra a 36W1/nohl Pas a21000kW GE gasturbine LM2500

figure 2.3

The CODOG,system contains of two MTU diesel engines for the cruise speed and two GE gas turbines for high speed The gearboxes have two gears, one for the diesel engine mode and one for the gas turbine mode. The diesel engines are coupled with multiple disc couplings and the gas turbines are connected with SSS clutches. When changing from the cruise mode to the boost

mode automatically the diesel engines are disengaged, second gear is switched on and the gas turbines are engaged. The performance diagram of this system is shown in the following figure.

All diagrams are set up with the assumption that the ship speed is direct proportional with the shaft and engine revolutions. The engine performance diagrams are originally set up against engine revolutions. These diagrams are recalculated and now set up against ship speed.

page: 7

Pa.. a3600 kW

MTU &owl alit

I2V 1163 TB 23

nw a2231/min

chapter 2 basis for the comparison COD OG 45030 42000 i., 2 x LM2503 _1

I

I

i , , c 30000 -4 ,

a

a

3 11 -1

-1

H --, E. I

iII

i

II 20030 1 rE t I 1 i hi 1 a 1 1 1 :15cozo - I -I II 1 I !I 1 OCCO 1. i 1 IF 7200 I 5000

I

2-x 12v1h5M3113-- F 20.1 1 I 131,5 50 ;10,0 15,0 20,0 25,0 30,0 35,0

ship speed [knot

... .

0

figure

40000

- CODAG 1 (COmbined Diesel And Gas turbine)

with one speed gearbox

-= nal/Min

man in 2201/min

CODAG plant with one speed gearbox

MW diesel engine'

20V 1163 TB 93

nearin 1350 1/min P.m 7400 kW

MTUdiesel engine

20V 1163 TB 93 newt 3600 1/nun GE gasturbine LM 2500 FM= n 21000kW

figure 23

In the CODAG system the diesel engines are used in the low speed region (cruise mode), but also at maximum speed (boost mode) together with the gas turbine. Between cruise speed and

maximum speed only the gas turbine propulses the vessel. The port and starboard gear units are connected by a cross connection gear. Both shaft lines can be operated independently in the cruise mode. The gas turbine is connected with the cross connection gear with a simple clutch. Between the cross connection and the gear units SSS clutches_{are fitted. The diesel engines are fitted with} Multiple disc couplings. The way of sailing is shown in the performance diagram on the next page.

page: 9

chapter 2 basis for the comparison

CODAG 1

with one speed gearbox

5 0 10,0 15,0 20,0 2Q9

/ship speed panel

30,0 0

figure 26

1 1 1 ii , 4 1 i 35800 kW 1,

ii

1 _E-x2OVIltot , II 1 i 1

I

I 21000 k 1x It 1 1 1 ri 1-1 1 III I 1.1 8300 kW I 1 x201/416371:193 I ii 1 1

1

, H 20,8 kn

r--26,9kJ.' 30,8an 35000 10303 25000 g 20000 e 15000 5000 40000

a

10000 0

- CODAG 2

with two speed gearbox

.in...a.. = 220 1/mm

= 220 1/min

MTU diesel engine 20V 1163 TB 93

= 1350 1/min

F-'-' = 7400 kW

MTU diesel engine 20V 1163 TB 93

CODAG with two speed gearbox

= 3600 1/mm

GE gasturbine LM 2500

= 21000 kW

figure 2.7

This solution differs from the previous only regarding the two gearboxes. The gearbox units have now two gears, one for diesel mode only and the other for the combined mode, diesel engine plus gas turbine. This results of course in big complexity and more weight. The advantage is that one

diesel engine can drive both shafts in the cruise mode. Above 19 knots thegas turbine takes over and the second gear is switched on. At boost speed all enginesare driving the ship. The diesel engine powers the ship at low speed only until 19 knots what corresponds with 80% load. This improves the life time of the engine. The performance diagram of this arrangement is shown in figure 2.4.

'chapter 2 'basis for the comparison

gure 2.8

-

-1

CODAG 2 with two speed gear

1 1 , 1 xLM isocr _____22azairanse , 35800 kW1 II -.... .... _ i II,

I

i

H'

ii s

a

1- 25030 L

;1

-.E. 1# I I 1 21000 kW 1 11 1-

.II

i 2CaX3 g it

a.

f I I II 45000 I 11 II 1-1 I II .1 I , ; 10000 7 -- ....

--1 1-,

---,

kW i I : ; I 5000 T

ier00

160...dassI9

! 1 , 1 x20V113 P. 1 kn 26.9 kn 308/at I i . 0 50 10,0 15,0 20 Øi 25,0 30,0 35,0 ihipsired [knotst , , I 45000 40000 35000 30000 1

- CODA!) 1 (COmbined Diesel And Diesel) with one speed gearbox

= 1350 1/min

PPM 7400 kW

CODAD plant with one speed gearbox

MN diesel engiie

20V 1163 TB 93

figure 2.9

The CODAD system consists of four identical diesel engines which are used in all speed regions,. Both shaftlines are run separately of each other. The diesel engines are connected by multiple disc

couplings with the gearbox. The gearbox consists ofone gear which is used in all speed regions. Two engines are used for cruising and all four of them will drive both shafts when high speed is needed. This is shown in the following diagram.

page: 13 = 210 1/min

/viTU did engine

20V 1163 TB 93

= 3600 1/min 7400kW

WV diesel engine

20V 1163 TB 93 MTU diesel engine

20V 1163 TB 93

chapter 2 basis for the comparison

figure 2.10

CODAD 1

withOWspeed gearbox,

1 40000 29600 kW 30CCO ..

1---i

4x2OVI1M 1 Ii il v 'ii III ii 11 III 2 *20V1163TB93 Isj 14 i 15000 . 160:101 -1 10000 kW i . 1- --i I ii I i. 22 k

I1ra

I, ' II i 29,4 kn i 50 10,0 15,0 . 20,0 250 30,0 35;0

ship speed [knotst

45000 120o00 a 5000 0 1 I

- CODAD 2

with two speed gearbox and cross connection

..$..,(ii.... 210 Ihrtfri

rm.= 210 1 /min

CODAD plant with two speed gear box

and cross connection

MILT diesel engine 20V 1163 TB 93

1350 'Aoki

7400 kW Mm diesel engine

20V 1163 TB 93

MTU diesel engine 20V 1163TB93

nom- 13.50 limin

7400 kW

Mil/ diesel engine 20V 1163TB93

figure 2.11

Like the CODAG system it is also possible to install a two speed gearbox and a cross connection in a CODA]) system, so the cruise mode can be covered by one diesel engine which drives both shafts. In the boost mode all engines are powering the ship through the second gear. The cross connection gear has an internal clutch in order to devide both shaft lines in the boost mode. All diesel engines are provided with a multiple disc coupling. In the following diagram the way of sailing is shown. Until 19 knots one diesel engine is used above this speed all four are engaged. It makes no sense to drive the ship with two diesel engines in the medium speed region because with the corresponding maximum speed will lie around 22 knots. In the cruise mode the diesel engine is only rated with 80% of its maximum rated power, in order to increase the engine life time.

chapter 2 basis for the comparison,

figure 2.12

CODAD 2

with two speed gearbox and cross connection

1 I , i5d00. I 1 , . 9600 kW 1 4x20V113

:.

1

r

4 i II 1 I I 200O3 iI i! ar 15000 I 1

1 iIi

II 10000 I I r I 15005 6000 kW 1 x20V1.163TB93 I i Ij

i Iisi

i

if

li Ili 1 11' 19 kn I II

thi

i I

I h I

. I 129Hikrz 1 1 I i

III-4

50 10,0 15,0 20,0 25,0 30,0 350

ship speedPuns]

-I-- ICR 1 (InterCooled and Recuperative gas turbine)

= 223 Ihnin

hoar = 223limn

ICR gasturbine plant

Rolls Royce Westinghouse ICR gasturbine

WR 21

= 3600 limin

= 19400 kW Rolls Royce Westinghouse ICR gasturbine

WR 21

figure 2.13

The ICR gas turbine promises, referring to the consortium Rolls Royce and Westinghouse, a fuel consumption saving of about 30%. That is why a single ICR gas turbine system is included in this study, although it would be more sensible to install these engines in a CODOG or CODAG arrangement, like the following systems. Each gas turbine is coupled with a SSS clutch with a single speed gearbox. The performance diagram is shown underneath.

chapter 2 basis for the comparison

figure 214

5,0. lotio 15,0 20,0 .35,0 30,0 3510

ship speed [knots]

ICR.,1 1 40000 38800 kW 1 1 , 1 1 i i i 2 xiVR I 35002

1-I 1 1 J 1 1 if I I I I I I ] I 15C00 1 1 loom scool I f 1 i i ,I 1 I I 313 kn 30000 ...

- ICR 2

in CODOG arrangement

- 225 limit

rams.. 225 1/min

ICR gasturbine in CODOG arrangement

MTU dsel engine

12V 1163 TB 83

1250 llmin Pm...4 3600 kW

MTU diesel engine 12V 1163 TB 83

Rolls Royce Westinghouse ICR gssturbine

WR 21

3600 1/mm

194C0 kW Rolls Royce Westinghouse ICR gasturbine

WR 21

figure 2.15

This is a normal CODOG system but the General Electric gas turbine is replaced by an ICR gas turbine. Further on everything is the same. The performance diagram is shown in diagram 2.9.

chapter 2 back for the comparison

figure 2.16

ICR 2

inCOD OG

5P 10,0 15,0 20,0

ship speed [knots]

30,0 35,0 1I T i 2 xWR 1 1 i 138860 kW

ill

J. i . I I , _iit 30003 i 11 I I If 1 li 1 1 I I 1 II I , _i I _I : , I 15000

li2

I 1 Il IT i k 1 i I! / 1 I II

r

10000 15000 I 7200kW1 I I li 2rV1163TEE3 I i I ' NO I

...;1111,'

120,1 kn I /I I 1 31,3 kn 45000 35000

}000

20000 25,0

figure 2.17

The ICR gas turbine is in this arrangement placed in a CODAG system. All details are the same as in the CODAG 1 system with the GE LM 2500 gas turbine. The next diagram shows the

performance diagram of this arrangement.

- ICR 3a

in CODAG arrangement with one speed gearbox and cross connection

z=<

= 220 1/min

rmac = 220 1/min

ICR sturbine in CODAG arrangement

MTU diesel engine 20V 1163 TB 93

Pau 7100 kw

MTU diesel engine 20V 1163 TB 93

5

Dna = 3600 11min Rolls Royce Westinghouse

/eR-gnsturbine--WR 21

Pm= = 19400 kW

page: 21

-chapter 2 basis for the comparison

ICR 3a

in CODAG with one speed gearbox

figure 2.18 I I I 34200 kW ; i 1 x FIT 2 x 20V1103 ! : ; 2 i i :93 1 1 I I ! ! i i I i -..19400 kW.-... I --"r 1 X.WR +.--. I 2 zPOV11631-13$ 8700 kW i 1 : ; ; --r-1-- I-: I I ; ! I i 1 i 20,3 kn 30,4 kn : I : 21,2 kn 5,0 10,0 15.0 _20,0 25,0 30,0 35,0

shiP need [knots] 45000 40300 35000 30000 25000 20000 15000 10000 5000 0 1 I.

ICR 3b

in CODAG arrangement with two speed gear and cross connection

thso 2101//min

ICR gastarbine in CODAG arrangement

MITI diesel engine 20V 1163 TB 93

ft= is 1350 lint

sr, 7400 kW

, MTU diesel engine

..,B=

20V 1163 TB 93

ras. 210 1/min

IT

3600

Rolls Royce Westinghouse 1CR gasturbine

WR 21

Pets 19400 kW

_figure 2.19

In this propulsion plant a two speed gear is fitted, with the advantage that one diesel! engine can. drive both shafts and propels the ship in the cruise mode. All details _{are the same as in the} CODAG 2 version. The following diagram shows the performance diagram.

page: 23

-=

=

chapter 2 basis for the comparison

figure 2.20

ICR

in CODAG with two speed gear.

as-coo 4200 kW

II

i I xWRI21 12 x 20V116,3 II:93 T 0-k I xWR 21 I r i

I50

_HI I,00001 a : it x20V11 hi 6000 kW 1:11: i e II, 5000 I las ri i I 26,3 kni130,4 kn i I 1 , I° t li I 1 ! ; ; l' 1 1 1 1 .1. 50 10,0 15,0 20,0 25,0 30,0 35,0, shipspecd (knots] 3b 1 45000

40

30000 25000 0

2.4 Chosen engines

For these different propulsion plants the following engines were selected:

table 2.2

In the next paragraph's the used engines will be described in more detail.

2.4.1 MTIT diesel engine

The MTU diesel engines are available in a wide range of power rating for marine applications, ranging from a 6 cylinders in line engine with 80 kW to a 20 cylinder V-engine with 7400 kW. For the frigate with 4000 ton displacement the engines with the most adequate performance diagram, that is the 12V 1163 TB 83 and the 20V 1163 TB93 engine with a maximum power rating of 3600 kW resp. 7400 kW dependent on the propulsion plant, was chosen. In the next figure the used MTU diesel engines abbreviations are explained.

20 number of cylinders, 20 cylinders

V cylinder arrangement, V-engine

1163 serie, cylinder displacement in litres x 100, 11.63 litre

T kind of air supply, turbocharged engine

B kind of charge air cooling, _{external charge air cooling}

marine application

3 _{design index index 3}

page: 25

type of system version diesel engine gas turbine

CODOG - 2 x 12V1163TB83 2 x LM2500 CODAG

1 +2

2 x 20V1163TB93 1 x LM2500 CODAD

1 ±2

4 x 20V1163TB93 -ICR 1 - 2 xWR 21 ICR 2 2 x 12V1163TB83 2 x WR 21 ICR 3a + 3b 2 x 20V1163TB93 1 x WR 21

figure

chapter 2 _{basis for the comparison}

The technical data of the engine and the performance diagrams are shown in the following tables and figures: 20V1163 TB 93 table 2.3 700.0 6500 6000It

±-1

5500 5000 4090 3500 3000 2500 2000 1500

'in

Taauacivawzia ffairA

AaMil

AiIneirmarg.

_ .41.fr.101111F1 MS', 111E"...ACAMENNS

_{--...zialmommt}

.L.Z0111111110,4011111111110 ,alff1111111111111Wag,MOUNI F?.3:211111/191WSP1M/11101MIM

amminsiwigimudimmirzearrammorarse

-.8.ANWEWArzaaar.-41111MINICIVAISIrara

miumpriylairar,..marraggpro..-wAnimo

Nommw.7 5....swerAtternumofammine

sinwr

imernAimur

_{predionimorammeasirko.}

slevAsulosimerdomammumanutzge,

Nue.amwaings.dne-imurammaam_Roomrem

Aursairrediewmummulmaimm

.

_r:r

P'

4-I 11 .71100k 130(Veor 67-5 kW °I260Asir e6221/2, number of cylinders 20

maximum power rating 7400 kW at 1300 to 13501/min

idle speed _{350 1/min}

V-angle of the cylinders _60°

bore _{230 nun}

stroke _{280 mm}

cylinder displacement 11.63 1

compression ratio 12

max. mean effective pressure 29 bar maximum power per cylinder 370 kW

specific power _{0.35 kW/kg} stvn9 Pa.., 20V 1163 TB 93 ; 7sOct ! I I I . - ; I-

+

I 0 300 goo 600 800 1000 1200 1350 1/ein _re 1

FH

---7

NBITN1111 I in! figure 2.23 12V1163 7B 83 table 2.4 PS kW 4000 5200 3800 4800 3600 3400 41100 ₃₂₀₀ 4000 3000 2800 3600 2600 3200 2400 2200 2800 2000 .1600 1630V 1200 1000 4270 800 Eno I ₆₀₀ 400 400 200 IQ 10

Elf

.... : ...

1=11 111111=1=11

Ma

OM =ME MI=

=I

ME

=I

MI MEM

II=

111:1115521,211111

MI=

MilliragArn

INIMAIWAWAIII

=I= grAtrano

_mm

_FAVAINTSTM

=111=11111115111FAMO=All

111=1110rAWATIMEMBE

MEMErillitiMEWAININI

11111111radMINIZEIMM

Itriell=1111

isnirtgarra

merawiragnanar

ran rairtrampro

114111110tr=S110111111:111111

111111111111=

MIME

rpm 300 400 page: 27 600 600 1000 1200 1300 I In' 'number of cylinders 12 1

maximum power rating _{3600 kW at 1200 to 12501/znin}

idle speed 350 1/min

V-angle of the cylinders 60°

bore 230 mm

stroke _{280 mm}

cylinder displacement 111.63 1

compression ratio 12

mean effective pressure _{25,8 bar} maximum power per cylinder 370 kW

specific power _{I 0.32 kW/kg}

Fuel .tor mew

3600 101 1200 P r 1.31 Wrap/ glulogunpi /clean 1.4.11 eland t .en/ aoo,!0" 2000. !goo P 41.131. . -200F

chapter 2 _{basis for the comparison}

MTU diesel engines have special devices, which allow the engine_{to have a wide performance and} good low load behaviour.

0 Cylinder Cut-out

The Cylinder Cut-out allows only one part of the cylinders to power the whole engine, what is very advantageous for low load operation regarding the combustion. The fuel injection for one cylinder bank is interrupted when the loads sinks below a certain limit. The working cylinders must overcome the friction and compression loads of the non working cylinders what leads to an increased fuel injection and results in_{a more complete combustion at higher temperature levels.} The effect is that the engine can operate with almost white-smoke-free exhaust gasses and with decreased oil dilution. In the 20V1163TB93 engine the cylinder cut-out is only used at idling speed.

0 Charge air preheating system

MTU diesel engines are equipped with a charge air preheating system which is switched on and off dependent on the engine load. At full load the charge air is cooled by sea water which increases the amount of air to be fed into the cylinders, which allows a more complete

combustion. At idling or at low load operation the inlet air is heated by a heat exchanger which is fed by the engine cooling water, as shown in figure 2.24. This technique improves the fuel

combustion process remarkable at low load.

CHARGE AIR COOLER CHARGE AIR PREHEATER - SEAWATER CONTROL SIGNAL ENGINE POWER

With both devices, the cylinder cut out and the charge air preheating system the fuel combustion is so good that the engines can be operated at low load (down to 120 kW per cil.) and at idle speed for unrestricted time without any limitations for later accelerations.

0 Two stage sequential turbocharging

The 1163 TB03, with a power output of 350 kW per cylinder, is equipped with a double stage turbocharge system. Two stage turbocharging is introduced with MTU engines, because such high cylinder powers need a charge air pressure of 5 bar. This charge air compression ratio is too high to achieve with a single stage turbocharger with a reasonable compressor operating range. Between the low pressure turbocharger and the high pressure turbocharger the charge air is

cooled by a sea water inter cooler. This will decrease the compression work and allows_the diameter of the high pressure charger wheels to be a lot more smaller. The sequential

turbocharging technique is based on changing the diameter of the turbine-entry depending on the load. That is done by cutting turbochargers in _{or out. This allows a better matching of the} turbocharger (fluid engine) with a diesel engine (piston engine). Resulting in raised charge air pressure and air volume at partial load as well as a higher turbocharger efficiency. This means an improvement in the performance range, specific fuel consumption and smoke behaviour.

This technique involves a common exhaust pipe after the cylinders and speed and/or

load-dependently controlled flaps before each turbine which, when closed, directsthe exhaust gasses to the remaining turbochargers in operation and achieves there a raised conversion of energy and improved efficiency. A flap at the compressor air inlet simultaneously_{prevents compressed air} escaping. The following picture shows the principle.

LP turbine LP stage LP compressor

/

Intercooler Attercoo4er I I I I L_1 i_J Li U Li L figure2.25 page: 29

MN=Exhaust gas(flowing,

ran Exhaust gas (non-fiovong) _{Externally operated exhaust valve} '---- Air (flowing) _{Check flap}

chapter2 basis for the comparison

2.4.2 GE gas turbine

General Electric has different gas turbines for marine propulsion, the LM 500, the LM 1600' and the LM 2500. In this study only the latter one is considered because of the high power

requirements for a 4000 ton displacement frigate at approx. 30 knots. The LM 2500 gas turbine is derived from the GE TF 39 (for military applications) and the CF6-6 (for commercial

applications) aircraft engines. They power the US Air Force C5A transport plane and the DC10 and other commercial aircraft's. According to General Electric over 500' LM 2500 gas turbines have already been installed in naval ships.

This gas turbine comprises a single shaft gas generator and _{a power turbine. Figure 17 shows the} principle of the LM 2500 gas turbine. The gas generator consists ofa variable geometry

compressor, an annular combustor and a high pressure turbine. Aerodynamically coupled with the gas generator exhaust gas is a multi-stage low pressure turbine, the power turbine, which

generates the output power.

air intake IC)1 combustor

[:>:

contpresor turbine power turbine

figure

2.26

The marine gas turbines are mostly delivered as a 'complete module, which includes a base frame;, an acoustic enclosure, flexible joints for intake air, cooling air and exhaust_{gas, a shock proof} mounting system and a fire extinguishing system.

In table 5 the performance data are listed and in figure 2.27 the _{performance diagram is shown.}

max. cont. power 'at 25°C

21000 kW

power turbine speed _{3600' 1/min}

-spec. fuel consumption _{0.241 kg/kWh}

I combustion air flow F 64 kg/s

1000 _{2000 3000 4000}

POWER TURBINE SPEED _ NPT-RPM

page: 31

chapter 2 basis for the comparison

2.4.3 ICR gas turbine

Rolls Royce and Westinghouse introduced on the marine marketan intercooled and recuperated gas turbine with an improved specific fuel consumption in the part load range. This engine is mainly based on the RB 211 aero gas turbine. Thecore contains of a two stage gas generator with a thermodynamically connected power turbine. Between the low pressure and the high pressure compressor an inter cooler is placed to cool the inlet air, in order to increase the amount of air compressed in the high pressure compressor. After this stage the air is led through a heat exchanger, where the exhaust gas of the power turbine heats up the combustion air before reaching the combustor. That results in a decreased fuel consumption, because the air is already heated up with the waste heat of the exhaust gasses. The principle of this engine is shown in figure 2.28.

WR-21 Intercooled/Recuperaled Cycle

Design features a twosnatt Care engine won intercooling between Me LP inc HP coMpressor 'eCuneration of exnaust heat between HP compressor outlet ana combustor inlet: anti a Pee

power turoine wen variaole area nozzle

LP Compressor HP Compressor 500 F 1227 C) Temp Increase BYPaSS %lady( y Combustor Fri A HP Turotne Recuperator woe. Exhaust 650 F (343 C) Turoine I I Powe, Turame

Variable Area Nozzle

1050 F (565. C;

figure 2.28

Rolls Royce and Westinghouse_{were able to fit the whole system within the footprint of the} simple cycle gas turbine LM 2500. The technical data is shown in table 6.

Rated power at 25°C

19.400 kW

power turbine speed 3600 1/min

specific fuel consumption 200 kg/kWh

air flow Water Inter-1 cooler 190 P V i106 Temp Drop Air inlet 1 A A

\

64

It was not possible to get a performance diagram of this gas turbine, but the curve with the specific fuel consumption could be provided. This is shown in figure 2.29.

gure 2.29 page: 33 0.4 0.38 0.36 0.34 7._^ 0.32 0.3 ..v ' 0.28 .2 0.26 6. u; 0.24 0.22 0.2 0.18 _ 0.16 0 5000 10000 15000 20000 25000 POWER (kW) I

chapter 2 basis for the comparison

2.5 Gearbox and clutches

The gearboxes and clutches for the arrangements are all different, as are already mentioned in chapter 2.3. Generally, the gearboxes comprise one or two reduction gears. For illustration the general lay out of a two speed gearbox with a cross connection (like for the CODAG 2 system) is shown in the following figure, because it is the most complex one.

gas-turbine

SSS clutch

cross connection

two speed gearbox

two speed gearbox

diesel engine

diesel

engine

figure 2.30

The two speed gear boxes are mounted near the diesel engines and contain two pairs ofcog wheels. In the cog wheel pairs multiple disc clutches are integrated, which are arranged in such way that not both clutches can be engaged. Thus only one pair can drive the output shaft. The cross connection is only a simple cog wheel arrangement which connects both output shafts and the input of the gas turbine. On one side of the cross connection is one small extra cog wheel fitted ( in figure 2.30 on the starboard side). That is because the turn direction of the diesel engines has to be the same and the propellers are turning into each other.

The other general lay outs of the other systems are more simpler and can be derived from this figure.

All the gas turbines are coupled with the gearboxes with self synchronising shaft clutches and the diesel engines are fitted with multiple disc couplings, instead of the in the past mostly usual fluid couplings.

The fluid coupling has four main disadvantages: high weight (ca. 1,5 ton)

A multiple disc coupling is set up much more simple. Because of the use of better materials and cooling devices the life cycle is increased. Another problem was engaging the clutch when the shaft were standing still. Now it is possible to break the shafts free with the use of short pressure pushes. This means short full engagements of the clutch in order to overcome the stick friction of the shaft bearings.

One can see from the performance diagrams in chapter 2.3 that the minimum speed of the ship, with the diesel engines running at idle speed and the propeller on full pitch is always higher than 5 knots. For manoeuvring in harbour, loitering or sonar operation it is necessary that also speeds under 5 knots are possible. This can be done in two ways. If there is no need for silent operation, then the propeller pitch is lowered. With the same shaft revolutions the thrust will decrease and the ship slows down. This driving mode causes cavitation, what results in underwater noise, and a slight decrease in efficiency. Another way of sailing slowly is used when the frigate is busy with sonar operation (active or passive). The propeller pitch has to be kept on the optimal pitch value in order to prevent noise by cavitation. The clutch is kept slipping, so the diesel engine can still

run on idle speed, but the shaft revolutions are lowered and the ship speed decreases.

2.6 Ambient conditions

The ambient conditions for this study are defined as:

table 2.7

The intake air depression and the exhaust back pressure represent the air pressure losses due to the ducts. The study is based on an air and water temperature of 25°C, which are average temperatures in summer in temperate seas.

The gas turbines are very sensitive to the air temperature concerning thepower rating.

The diesel engines can be rated to their maximum power at a water temperature of 32°C and a air temperature of 25°C. If the air temperature increases to 45°C then 3% of the power is lost.

page: 35

air temperature 25°C

sea water temperature 25°C

barometric pressure 1013 mbar

intake air depression (diesel engine) 15 mbar intake air depression (gas turbine) 10 mbar exhaust back pressure (diesel engine) 30 mbar exhaust back pressure (gas turbine) 15 mbar

chapter 2 basis for the comparison

2.7 Propeller

For propelling a frigate with 4000 ton displacement nowadays only Fixed Pitch Propellers (FPP) or Controllable Pitch Propellers (CPP) are normally used. Although a FP propeller has a better efficiency, most Navy's choose a CP propeller, because of the better manoeuvrability capabilities. Another advantage is that no reverse gear is necessary for the chosen engines, which are not able to change the turning direction. Good manoeuvrability is of very great importance for a warship (as is explained in chapter 2.2), so that in this study a CP propeller is chosen. In the following table the CP propeller data are listed.

table 2.8

diameter 4.2 m

max. pitch ratio 1.44 max. shaft-speed 225 Ihnin number of blades 5

area ratio 70 %

3. Propulsion plant comparison

With the basis knowledge of chapter 2 it is now possible to investigate the differences of the arrangements and their consequences on the ship. First of all the achievable speeds are evaluated, following by the dimensions and the weight. After this the life cycle costs and the operating range are calculated. The reliability, redundancy and manoeuvrability are shortly discussed, before dealing with the last two important items, the infra red signature and the noise radiation.

3.1 Speed comparison

The performance of the propulsion plant is the most important item to investigate. If the

performance is unacceptable then another propulsion system has to be found, although other items like the costs or fuel consumption are attractive. In the following paragraphs the performance diagrams of the engines are combined with the power demand curve of the ship and the maximum achievable cruise and boost speed are calculated.

3.1.1 Maximum speed

The maximum speed is easy read from the performance diagrams presented in chapter 2.3. The maximum speed and the corresponding maximum power ratings are listed in table 3.1.

table 3.1

From table 3.1 one can see that the maximum speed does not exceed 32 knots and does not differ very much, although the maximum available power has a wide range from 44000 kW to 29600 kW. That is due to the hull resistance, which is in first approximation proportional to the second power of the ship speed. The power demand curve is therefore approximate proportional to the third power.

For all systems the achieved maximum ship speed is acceptable. More than 30 knots are normally not required and are used very seldom, what can be seen in the operation profile (figure 2.2).

page: 37

type of propulsion system maximum power [IcW1 maximum speed (knots) 31.5 CODOG 42000

CODAG 1 with one speed gear 35800 30.8

CODAG 2 with two speed gear 35800 30.8

CODA]) 1with one speed gear 29600 29.4

CODA]) 2 with two speed gear and cross connection

29600 29.4

ICR 1 38800 31.3

ICR 2 in CODOG 38800 31.3

ICR 3a inCODAG

with one speed gear

34200 30.4

ICR 3b inCODAG

with two speedgear

34200 30,4

I

chapter 3 propulsion plant comparison

3.1.2 Cruise speed

The maximum cruise speed is determined by the maximum power the cruise engine can deliver as is seen in the performance diagrams in chapter 2..

table 3.2

This installation has only one type of engine, it is used with anise speed and with max speed

The achievable cruise speed of all arrangements is acceptable, because the cruising speed, referring to the operating profile, lies around 19 knots. This can easily maintained with all

systems.

The propulsion systems with a two speed gear drive and possibility of using one engine for both shafts are only driven up to 19 knots, which corresponds with a rated power of 6000 kW. It is theoretical possible to rate the engine with 7400 kW (360 kW/cyl), corresponding to 20 knots. But that will decrease the engine life time in a high degree, so it is better to limit the diesel engine operating range to 80% or 19 knots to get long time between overhauls (TBO). Looking on the operating profile in chapter 2.2 one can conclude that 19 knots are sufficient for the cruise mode, because then 90% of the time the ship can be driven with one of the diesel engines.

The 12V1163TB83, used in both CODOG instillations, on the other hand can be loaded with the maximum power, because this engine is already blocked to a lower specific load of 300 kW/cyl. what corresponds with an output power of 3600 kW having a more realistic TBO value.

3.2 Dimensions

The dimensions of the whole propulsion installation are of no great importance. By a military vessel the engine compartment dimensions are on the forehand defined by the damage stability criteria. The distances between the bulkheads of a 4000 ton frigate are that large, that almost every propulsion engine can be fitted in there. The dimensions of the engines and the gearboxes are mentioned for the completeness. In a second paragraph the dimensions of the air ductings for the engines are calculated and compared.

type of propulsion system maximum

speed [knots]

CODOG 20.1

CODAG 1 with one speed gear 20.8

CODAG 2 with two speed gear 19

CODAD 1 with one speed gear 22

CODA]) 2 with two speed gear and cross connection

19

ICR 1* 31.3*

ICR 2 in CODOG 20.1

ICR 3a in CODAG with one speed gear

21.2

.

ICR 3b in CODAG with two speed gear

19

-3.2.1 Dimensions of propulsion engines

There are four different propulsion engines; two types of MTU diesel engines, the LM 2500 and the ICR gas turbine. The diesel engines are delivered with a sound enclosure, base frame and the mounting system. The LM 2500 and the ICR gas turbine are built in a module including the sound enclosure with a single mounting system. The dimensions of the modules and the required surface and volume are listed in the table 3.3.

table 3.3

In some applications the diesel engines are mounted in a double module, if fitted in pair. This is done, because the distance between the shafts is so small (under 6 m) that it is not possible to build two single modules next to each other. This is not the case in this frigate with a beam of 15.7 m. The distance between the shafts is 6.8 m. So, only single modules are considered.

The ICR gas turbine needs the most volume, but has the same surface than the LM 2500gas turbine. It was a requirement that the ICR engine should be fitted into the same footprint as the LM 2500. The more space is mainly taken by the recuperator, which is mounted on top of the

engine.

For the gearboxes the overall dimensions are listed below.

The main dimensions depend largely on the required speed reduction and the number ofgears and cross connections. This is almost for each installation different, so that six different gearboxes are necessary. The ICR gas turbine arrangements are fitted with the same gearboxes than the General Electric gas turbine arrangements.

The dimensions are shown in the following tables.

table 3.4

page: 39

engine type length [mm] beam immil height imm] surface fm21 volume [m21

20V1163TB93 6550 2300 3962 15.10 59.69

12V1163TB83 5200 2300 3962 11.96 47.39

LM 2500 8000 2650 2900 21.20 61.48

WR 21 8000 2640 4826 21.10 101.93

CODOG CODAG 1 CODAG 2 CODAD I CODAD 2

gearbox length [rum] 4800 3800 3800 3300 3800 beam [mm] 4250 5000 5000 3500 5000 height [mm] 2750 2200 2200 2500 2200 surface [ml 20,4 19 _{19 11,55 19} volume [ml] 56,1 41,8 41,8 28,8 41,8 cross connection length [mm] 1900 1900 2000 beam [mm] 6700 6700 ₆₀₀₀ height [nun] 2100 2100 2100 surface [m2] 12,73 12,73 12 volume [m3] 26,7 26,7 25.2 ' , _I , I I

chapter 3 propulsion plant comparison

table 3.5

3.2.2 Dimensions of air ducts

The air inlet and exhaust gas ducting have different dimensions for the different versions. This is also an important item to evaluate, because of the required space above the engine room and in the funnel.

The diameter of the ducts are taken from the manuals of the corresponding engine. Additional the needed volume is calculated with an assumed height of the engine room of 4.5 in. The exhaust ducts are only considered until the entry of the funnel, on the level of the main deck. For the dimensions the German F122 is taken as a basis. In the following tables the results of these calculations are shown.

table 3.6

ICR 1 ICR 2 ICR 3a ICR 3b

gearbox length [nun] 4800 4800 3800 3800 beam [mm] 4250 4250 5000 5000 height [nun] 2750 2750 2200 2200 surface 1m2] 20,4 20,4 19 19 volume [re] 56,1 56,1 41,8 41,8 cross connection length [mm] 1900 1900 beam [mm] 6700 6700 height [min] 2100 2100 surface 1m21 12,73 12,73 volume Em'] 26,7 26,7

exhaust gas ducting

system diameter of exhaust gas duct of diesel engine diameter of exhaust gas duct of gas turbine total volume CODOG 2 x 800 2 x 2200 34,43 CODAG 1 2 x 900 1 x 2200 20,29 CODAG 2 2 x 900 1 x 2200 20,29 CODAD I 4 x 900 10,18 CODAD 2 4 x 900 10,18 ICR 1 1 x2200 30,41 ICR 2 2 x 800 2 x 2200 34,43 ICR 3a 2 x 900 1 x 2200 20,29 ICR 3b 2 x 900 1 x 2200 20,29 II I

-I

table 3.7

figure 3.1

One can see that the exhaust gas and inlet air ducts for arrangements with gas turbines require more space than the CODA]) arrangements, due to the higher air flow. Especially both CODOG systems need a lot of space for their air ducts. The CODA]) arrangements are advantageous if above the engineroom not much space is available. Alternatively the exhaust duct of these arrangements can also be led through the side of the ship on the height of the waterline. This is not possible for gas turbines, due to their large required diameter of the exhaust duct and their high sensitivity for exhaust gas back pressure. The exhaust gas back pressure can increase rapidly if water closes the opening of the exhaust stack.

page: 41

inlet air ducting

system diameter of

inlet air duct

of diesel

engine

diameter of inlet air duct of gas turbine total volume CODOG 2 x 1200 2 x 2700 54,85 CODAG I 2 x 1800 1 x 2700 43,26 CODAG 2 2 x 1800 1 x 2700 43,26 CODAD 1 4 x 1800 40,72 CODAD 2 4 x 1800 40,72 ICR 1 2 x 2800 49,26 ICR 2 2 x 1200 2 x 2800 58,31 ICR 3a 2 x 1800 1 x 2800 44,99 ICR 3b 2 x 1800 1 x 2800 44,99 -I

chapter) propulsion plant comparison

3.3 Weight

The weight of the propulsion plant which was compared includes the weight of the propulsion engines and the gearboxes. As already mentioned before, the weight of the propeller shaft and the propeller is not included in this comparison, because these items are for all arrangements the same. In table 3.8 the weight of all these details are listed.

The weights of the propulsion engines include the base frames, mounting systems and the sound enclosures. The weight of the gearboxes contain also the weight of the clutches and auxiliary systems, like oil dash cooling system.

table 3.8

type of propulsion system diesel engines including module [ton] gas turbine modules [ton] gearboxes [ton] total weight [ton] CODOG 78,2 28 96 202,2 CODAG 1 102,8 14 92 208,8 CODAG 2 102,8 14 102 218,8 CODAD 1 205,6 64 269,6 CODAD 2 205,6 85 290,6 ICR 1 101,4 86 187,4 ICR 2 78,2 101,4 96 275,6 ICR3a 102,8 50,7 92 245,5 ICR 3b 102,8 50,7 102 255,5 I ' I 1

The ICR 1 is clearly the lightest solution. The other ICR installations are heavier than the CODOG and CODAG versions with GE gas turbines. This is due to the high weight of the ICR gas turbine, because of the recuperator.

Both CODAD arrangements are relatively heavy due to the weight of the base frames and sound enclosures of the diesel engines.

The weight of the installation is of importance regarding the operating range, which is dealt with in chapter 3.5.

3.4 Life cycle costs

Every planning staff of the Navy is nowadays aware of the financial aspects of building or buying new battleships. Therefore the economical aspects are included in this study. The life cycle costs consist of:

first costs

operating costs; which can be subdivided into:

fuel costs lube oil costs personnel costs maintenance costs.

3.4.1 First costs

The budget price of the propulsion plant is considered, which is based on quotations of the manufacturers. The diesel engine and the gas turbine prices include the base frame, the mounting system and the sound enclosure and all the necessary auxiliaries. The multiple disc couplings or the SSS-clutches are included in the prices of the gearboxes. The shaft line arrangement and the propeller are not included in this study, because each plant has almost the same shafting and propeller. The mentioned prices are budget prices.

table 3.9

page: 43

type of propulsion system diesel engines including module

[Mill DM]

gas turbine module

[Mill DM] gearbox [Mill DM] total initial costs [Mill DMI CODOG 7,2 22,4 6,5 36,1 CODAG 1 11,0 11,2 6,0 28,2 CODAG 2 11,0 11,2 7,6 29,8 CODAD 1 22,0 3,8 25,8 CODA]) 2 22,0

-

5,0 27,0 ICR 1 25,2 5,5 30,7 ICR 2 7,2 25,2 6.5 38,4 ICR 3a 11.0 25,2 6,0 42,2 ICR 3b 11,0 25,2 7,6 43,8 . , , ,,

-7 6 5

a

4 C 3 2 1 31,51m 30,81m

17-7

30,8 la 29,4 im first costs 29,4

a

31,3 bi 30,41m 30,4 bi "777777 kind of system

figure 3.3

From figure 3.3 it is seen that the simple CODAD 1 plant has the lowest first costs. Due to the high price of the two speed gearbox and cross connection the CODAG 2 and the ICA 3b installations are the most expensive one's. The CODAD 2 system, which has also a two speed gearbox shows relatively low first costs.

In figure 3.3 also the achievable speeds of the arrangements are shown, in order to get a better overview.

3.4.2 Operating costs

The operating costs of military naval vessels are of more importance in the last couple of years, because the defence budget in most countries is cut down. So it is interesting that the already expensive navy ship's have low operating costs Operating costs consist of:

fuel costs lube oil costs personnel costs maintenance costs.

The costs are calculated on the basis of the life time of the ship and of the:operating profile Oft chapter 2.2). ,:,.. M.:... .. : .... N IS ei CO .0 01 ..gt

0

0

44

0

0

Q.

0

Q C4 c...) C4i c...)

I.

en 44 ca, en 44 IC.)

0

0

0

U U U U

3.4.2.1 Fuel costs

The fuel consumption is of great importance for naval vessels. This is not only because of the fuel costs, but also regarding the amount and weight of the carried fuel for a mission. How less the engines consume the larger the operation range can be at a given amount of fuel storage.

The fuel consumption of all mentioned propulsion systems are calculated on a years basis. This is done with the use of performance diagrams of the used propulsion engines (chapter 2.3), the operating profile (chapter 2.2) and the required power curve of the regarded frigate (chapter 2.1). In chapter 2.3 the engine performance diagrams and the required power curve of the ship are already combined and the operation mode is determined. In the engine performance diagrams lines for constant specific fuel consumption are drawn (chapter 2.4). The specific fuel consumption can now be read from the diagram at the required power and the engine revolutions, corresponding to the ship speed. To get the fuel consumption per year each specific fuel consumption value at a certain ship speed is multiplied with the required power and the annual operation time. Adding the fuel consumption of all engines the total consumption is determined. In the appendix 1 the

detailed calculation is shown. In table 3.10 and figure 3.4 the result is shown. In figure 3.4 the maximum ship speed of each arrangement is additional mentioned.

table 3.10

page: 45

OVERVIEW

Ron/year]

CODOG 2.027 CODAG 1 one speed gear 1.931

CODAG 2 twospeed gear 1.865

CODAD I one_{speed gear} 1.661

CODAD 2 two speed gear

and cross connection

1.662

ICR 1 2.266

ICR 2 in CODOG 1.243

ICR 3a in CODAGone

speed

1.697

ICR 3b in CODAG two speed

1.695

LM 2500 3.459

I

§ 1 000

500

0

figure

3.4

The CODOG system and the single ICR gas turbine system have clearly the highest fuel

consumption. The most economic is the CODOG installation with the use of the ICR gas turbine (ICR 2) which has also the second highest ship speed.

Amazing is the relatively high fuel consumption of all CODAG systems, especially the one where one diesel engine chives both shafts in low speed operation. This is due to the combined operation of the diesel engines and the gas turbine.

For a comparison of the ICR gas turbine installation with a simple cycle gas turbine the fuel consumption of an installation with only a pair of LM 2500 gas turbines is included. The advantage of the intercooled and recuperated gas turbine is clearly visible.

The fuel costs can now be calculated on the basis of the, al:Fe:rage price for marine diesel oil (MDO) in Europe which is assumed to be 114 DM per ton.

propulsion plant comparison

fuel consumption per year

31,5 hi i type of propulsion system fuel costs [DM/year" fuel cost [Mill DM/lifel CODOG 1 231.062 5,78 CODAG 1 1 220.170 5,50 CODAG2 I 212.657 5,32 CODAD 1 i 189.362 4,73 CODAD 2 189.477 4,74 1CR 1 258.332 I 6,46 ICR 2 I 141.734 3,54 ICR 3a 193.506 4,84 .0

0

N 0

a

o

.- N or in cc

a

a

.0,

o

o

Ni re

o

re:Cg. 0 A cc 0 0 ,0

0

0

0

0

kind of propulsion system

-2.500! 7 _{31,3 im} " 2030 is I 31,5 km 30,8 1m _{30,8 in} 29,4 kn 29,4 kn 30,4 Im 30,4 kn it 1.500 _{31,3 la} 7717,7 0 3.500 -3.000 chapter 3

3.4.2.2 Lube oil costs

The lube oil consumption for the gas turbines is neglectible and for the diesel engines it is 0,5% of the fuel consumption plus the lube oil change every 1000 operating hours. The diesel engines need the following amount of lube oil:

12V1163TB83: 500 litre

20V1163TB93: 830 litre

The lube oil costs are shown in table 3.12 and in figure 3.5.

table 3.12 14,00 12,00 f:21 10,00 8,00 e+ 6,00 4 4,00 2,00 0,00

lube oil costs per ship life

c4 cm c; 04 < 0 cz

c

a

c

C 0

₀

_o 0 0 0

kind of sys tem

tN

figure 3.5

page: 47 type of propulsion system

lube oil costs [DM/year]

lube oil costs

[Mill DM /life time] CODOG 210.236 5,26 CODAG 1 366.160 9,15 CODAG 2 185.318 4,63 CODAD 1 404.976 10,12 CODAD 2 227.093 5,68 ICR 1 0 0,00 ICR 2 213.654 5,34 ICR 3a 354.458 8,86 ICR 3b 179.815 4,50 ' , ,

chapter 3 propulsion plant comparison

3.4.2.3 Personnel costs

The personnel costs are difficult to calculate, because the required number and the salary of the engine room personnel differ from Navy to Navy. The engine room personnel is derived from previous MTU reports and statements of the German Navy. The estimated requirement of personnel fora 24 h operation with a 3 guard system is stated in table 3.13. In a diesel engine room 2 men are needed and in the gas turbine compartment only 1 is required. An average salary of 35000 DM per year and per engine room technician is estimated.

table 3.13

The ICR 1 installation needs the least personnel, but this arrangement has only two propulsion engines. In general the installations with gas turbines use less personnel than the arrangements with only diesel engines. In the last colomn the calculated yearly costs are shown.

3.4.2.4 Maintenance costs

The maintenance costs of the propulsion engines depend mainly on the operating hours and on the operating profile of the engine. The costs for the diesel engines are calculated with the help of a special MTU maintenance computer programme. The result of this programme is shown in annex 3. The gas turbines generally do not need so much and detailed maintenance as the diesel engines. The main maintenance action is the hot section repair, but the rated power of the gas turbines (excluding the gas turbine in the ICR 1 arrangement) has been chosen in order to avoid a hot section repair interval in the whole ship life. The maintenance costs of the gas turbines can be calculated on the basis of a general price per operation hour, which is listed in the table underneath.

table 3.14

The ICR 1 installation has too much operation hours per engine, so that during the ship life, which

type of propulsion system diesel engine compartment gas turbine compartment total requirement personnel costs [mill DM] CODOG 6 3 9 0,315 CODAG I 6 3 9 0,315 CODAG 2 6 3 9 0,315 CODAD 1 12 12 0,42 CODAD 2 12 12 0,42 ICR 1 3 3 0,105 2 ,ICR 6 3 9 0,315 ICR 3a 6 3 9 0,315 ICR 3b 6 3 9 0,315

gas turbine general price

per operation hour

LM 2500 28 DM

WR 21 35 DM

WR 21 with hot section repair interval 190 DM

'

The total maintenance costs for the arrangements are shown in table 3.15.

10

9

a

figure 3.6

# hot section repair interval is required for gas turbine

It was expected that the arrangements with a two speed gearbox and a cross connection have a reduction in the maintenance costs comparing them to the more simple arrangement with a single speed gearbox. This is due to the ability to power the ship with only one diesel engine and

reducing in that way the operating time per engine. This reduction in maintenance ( CODAG 2, CODAD 2, ICR 3b) can clearly be seen in figure 3.6. The gas turbines in the CODAG 2 and ICR 3b arrangements do not need a hot section repair interval what reduces additionally the

maintenance costs.

The CODAD 1 system, but also the CODAD 2 system, have attractive maintenance costs,

although 4 diesel engines are fitted, but they do not need a general overhaul during the life time of the ship.

The CODOG system and the ICR 2 arrangement have also relatively low maintenance costs.

type of propulsion system CODOG CODAG 1 CODAG 2 CODAD 1 CODAD 2 ICR 1 ICR 2 ICR 3a ICR 3b gas turbine maintenance costs [Mill DM/ship life] 0,238 2,9 1,099 0,098 0,14 9,5 0,285 0,118 0,168 diesel engine maintenance costs [Mill DM/ship life] 1,44 2,204 1,75 1,44

039Sie

2,9 1,099 table 3.15

maintensuice costs per ship life

8

kind11 system page: 49 costs "Mill DM/ship life] 1,678 11 2,998 1,75 9,5 1,725 3,018

chapter 3 propulsion plant comparison

The ICR 1 installation has the most maintenance costs of all installations, due to the required 6 main overhaul intervals.

3.4.3 Total costs

All the operating costs are listed and added together in the following table.

table 3.16

From this table it can clearly be seen that the personal costs are an important part of the life cycle costs. In the last colomn of table 3.16 the life cycle costs without the personnel costs are shown, because the number and payment of the engine room crew depends too much on the user.

tYPo of

propulsion

,

r lune oil costs 1 1 1 1 personnel costs maintenance costs

life cycle costS hfe cycle costs exclusive pxsonnel costs Mill DM/ship life] [Mill DM/ship life] [Mill DM/ship ' life] [Mill DM/ship life] Dal DM/ship life] [M111 DM/ship LS] -CODOG 5.776.551 5 255 889 7.875.000 1,678 20,59 12,71 CODAG 1 5.504.256 9.154.009 8.190.000 2,998 25,85 17,66 CODAG 2 5.316.424 1 4.632 957 8.505.000 1,239 19,69 11,19 CODAD 1 4.734.050 12.396.745 8.820.000 2,204 28,15 19,33 CODAD 2 4.736.934 7.951.047 9.135.000 1,75 23,57 14,44 ICR 1 6.458.294 0 9.450.000 9,5 ' 25,41 15,96 ICR 2 3.543.348 1 5.341.347 9.765.000 1,725 20,37 10,61

fl 3a

4.837.653 ' 8.861.448 10.080.000 3,018 26,80 16.72 IC1t. 3b I 4.830.471 1 4.495383' 10.395.000 1,267 ,.,.:' 20,99 - 1039 system fuel costs

To get a better overview these figures are set up in a diagram, see figure 33.

operation costs

(exclusive personnel costs)

11 20,00 211,00 16,00 14,00-12,00 5_{g 10,00} 0.00 6,00 4,00 Zoo , r o C.; cy in

<

ni

ii

i

a

c.) -_.

a

0

8

8

8

kind of system

figure 3.7

hot section repair interval is required for gas turbine

From figure 3.7 it can be seen that the CODAG 2, ICR 2 arid the ICR 3b installation have the

least life cycle costs. The

CODAG

2 and ICR 3b propulsion plants have a complicated and therefore expensive engine arrangement (two speed gear with cross connection), but due to the acceptable fuel consumption and the least maintenance costs of all propulsion plants the operating costs are low.

The propulsion plants with a more simple engine arrangement, like theCODAD 1, CODAG 1 and the ICR 3a arrangements, where only one speed gearbox and a cross connection is fitted, are the most expensive arrangements.

The ICR 1 system has high operation costs, due to the required 6 overhaul period&

In the following table 3.16 the operating costs and the first costs are added together to get the total life cycle costs, which are also shown in figure 3.8k

table 3.17

page: 511

type of propulsion

I system

life cycle costs exclusive

personnel

costs

first costs total life cycle

costs [Mill DM/ship life] [Mill DM] [Mill DM] ; CODOG 13,31 1 6,5 19,81 CODAG I i 18,46 I 6 I 24,46 I CODAG 2 L 11,19 7,6 18,79 1 CODAD 1 19,33 J 3,8 23,11 CODAD 2 1 14,44 5 I 19,44 i ICR 1 15,96 i 5,5 1 21,46. 1CR 2 1 11,21 6,5 L 17,71 i ICR 3a 17,52 6 23,52 ICR 3b I 1%59 I 7,6 1 18,19 !

chapter 3 propulsion plant comparison

figure 18

When looking on the life cycle costs the ICR 2, ICR 3b and The CODAG 2 installations are the most economical ones during the whole ship life.

3.5 Operating Range

The operating range of the ship will be determined with the fuel consumption data the fixed weight of the whole propulsion system and the operating profile shown in chapter 2.3. The weight of the propulsion system plus the loaded fuel is assumed to be limited to 600 ton. The amount of fuel which can be carried is determined by the difference of these 600 ton and the already

calculated weight of the propulsion arrangement (chapter 3.3). With the calculated fuel

consumption in chapter 3.4.2.1, in which the effect of the operating profile is already included, the range can be calculated. In the table 3.18 and figure 3.9 the result is shown.,

table 3.18 kind of system 25.00 20,00 15,00 -7717

life cycle costs

41 10,00 -N$ 5,00 - I"

i

III III.

4

tt 0,00 N ce Ord' tzi

2

2

v

8 8 8 system range on basis operating profile [mall CODOG 5597,45 CODAG 1 5776,90 CODAG 2 5828,11 CODAD 1 5672,83 CODAD 2 5309,06 ICR 1 5192,85 ICR 2 7441,52 ICR

la

5956,29 KR3b 5796,88

i000,00 -7000,00 -7 6000,00i-1 5000,001 -i4000,00

3000,00 MON '1000,00 -0,00

operation range on basis of tbe operation profile

CODOG CODAG CODAG CODA]) CODA]) ICR 1 ICR 2 ICR 3a ICR 3b

1 2 1 2

kind of system

figure 319`

From the above shown figure it can be seen that the ICR 2 system has the greatest operating range, although it has a quite high weight, but the advantageous fuel consumption compensates this disadvantage. All the other systems have almost the same range of about 5600 iseamiles.,

3.46 Reliability, redundancy and manoeuvrability'

Comparing the reliability and redundancy of the installations is difficult, because concrete reliability data's are not available. Besides the therefore necessary statistical calculation would be too large scaled for this study. Thus, this item is only evaluated in a qualitative manner.

In general there is no big difference in the reliability figures between gas turbines and diesel engines. The gearboxes have in general an excellent record of reliability. A more complicated gearbox has of course a bigger chance for a failure than a simple one, due to more cog wheels. Thus the installations with a two speed gearbox and a cross connection will have a greater probability for a breakdown than the one speed reduction gear units

page: 53

chapter 3 propulsion plant comparison

The redundancy of the propulsion engines are shown in table 3.19 . There are three forms of redundancy thinkable with these installations.

3 : there are 3 other propulsion engines available to propel the ship

2 : there are 2 other propulsion engines available to propel the ship

1 : there is 1 other propulsion engine available to propel the ship

table 3.19

The getting home possibility for each propulsion arrangement is available. It is subject for each planning staff of a Navy to make the requirements for the redundancy and make a detailed reliability calculation.

Under manoeuvrability one understands the acceleration behaviour of the engine. Due to the wide performance diagram of the MTU diesel engines and the use of controlled pitch propellers, there are no significant acceleration differences between gas turbine powered ships and diesel engine powered ships. Also crash stop manoeuvres with almost the same braking distance are possible with all regarded propulsion arrangements.

More than this description cannot be given, because a solid comparison requires a simulation run of all installations.

3.7 Infra Red Signature

The delectability of navy ships is to a great extent due to their infra red signatures. With the use of sensors which can detect electromagnetic radiation in the infra red spectral range it is possible to detect naval targets by recognition of hot spots of the ship's outer skin. The exhaust gasses and exhaust stacks play a key role in the IR signature. The infra red sensors are working in two basic wavelength bands:

0

3 - 6 gm

4

7 - 15 gin

type of installation redundancy per ship

CODOG 3 CODAG 1 2 CODAG 2 2 CODAD 1 3 CODAD 2 3 ICR 1 1 ICR 2 in CODOG 3 ICR 3a in CODAG 2 ICR 3b in CODAG 2 '