Proceedings of the 4th Ship Control Systems Symposium, Den Helder, The Netherlands, Volume 6

(1)

2 1

DEC. 19

NRcHiaPROCEEDINGS

Lab. v. Scheepsbouwkund

Technische Horst:loci

(2)

THE SYMPOSIUM WILL BE HELD IN THE NETHERLANDS,

THE HAGUE - CONGRESS CENTRE - 27-31 OCTOBER 1975

Statements and opinions expressed in the papers are those of the authors, and do not necessarily represent the views of the Royal Netherlands Navy.

The papers have been reproduced exactly as they were received from the authors.

(3)

VOLUME 6

CONTENTS

SESSION Pl:

Chairman: R.W. Stuart Mitchell

Professor in gasturbines, Departement of Mechanical Engineering, Delft,Univer-sity of Technology

The design and simulation of an automatic load control for maneuvring tests of the FFG-7 and DD-963 propulsion

systems.

J.W.Donnely and D.Keyser.

Development of a modern remote propulsion control system for the R.Neth. N. guided missile frigates.

F.J. van den Berg, J.Brink and C. van der Toorn.

Application of simulation techniques to the DDH-280 class propulsion machinery.

F.R.Livingstone and J.M.Kuran.

Operating experience with electronic control systems in gasturbine driven warships.

J.B.Strugnell, R.J.L.Corser and B.J.McD. Gowans

SESSION P2:

Chairman: L.G.Holtby

Commander, Head machinery control systems and interior communications section, National Defense Headquarters, Ottawa

An experiment to determine the effectiveness of the col-lision avoidance features of a surface ship bridge controle

console.

see supplement A.D.Beary Jr. and W.J.Weingartner.

Human transfer function in ship steering - the effect of _6-112 "feel" in the wheel.

A.M.Stuurman.

Computer aided pilot house design. A systems approach _6-131 F.S.Underwood and G.D.Buell jr.

Simulation of ship manoeuvring under human control. 6-148

W. Veldhu;.zen en H.G.Stassen.

SESSION B (see volume 1)

The development of a machinery control system from the

initial 6-164

concept through to the final ship trials.

P.Mason, G.B. Conventry, A.M. Dorrian.

Page

6-1

6-15

6-56

(4)

SESSION Dl: (see volume 2)

The plight of the operator J.Stark and J.Forrest.

SESSION (see volume 3)

Surface ship bridge control system. M.A.Gawitt.

SESSION NI: (see volume 5)

Naval ships control reliability: a hardware-software

issue. P.P.Dogan . Page see supplement see supplement 6-178

(5)

DESIGN AND SIMULATION OF AN AUTOMATIC LOAD CONTROL FOR MANEUVERING TESTS OF THE DD-963 AND EEG-7 PROPULSION SYSTEMS

BY

J. W. DONNELLY D. R. KEYSER

Senior Project Engineer Senior Project Engineer

Member, ASME

Naval Ship Engineering Center, Philadaphia Division Philadelphia, PA 19112 ISA

SYNOPSIS

In the past, the shore test agenda of propulsion systems has been limited to "steady steaming" power profiles and endurance requirements. With the advent of more sophisticated propulsion systems, including electronic controls, maneuvering requirements have been added to the criteria. To perform these

transient load tests, an automatic load control has been designed to follow closely the maximum shaft loading rates that can be delivered by the gas turbine propulsion systems of the DD-963 and the FFG-7. For the first time, realistic propulsion machinery sea trials can be run on land.

INTRODUCTION

The feasibility of conducting emergency maneuvering shore tests on the FFG-7 and DD-963 propulsion systems is clearly demonstrated in this paper. Since these propulsion systems combine gas turbine power with a controllable reversible pitch propeller, the shaft torque and speed transients are characteristically more complex and rapid than those tested heretofore.

The water brakes involved possess the load absorption capacity to simulate the shaft loading and speed changes involved in emergency maneuvers, but their performance has been limited to "steady steaming" by slowly moving, manually operated inlet and outlet

Nomenclature

valves.

Subscripts

P pressure psfg N/m2 B brake

W mass of water lbm Kg c water brake cavity

N shaft speed rpm rpm i inlet

Q shaft torque _lb.ft N.m o outlet

W flow rate lbm/sec Kg/sec s supply

T temperature m water brake manifold

h ambient heat loss _btu/sec _Kcal/sec _d

demand X A dimensionless valve position difference 7 V valve

(6)

Replacing these valves with larger automatically controlled valves would permit maneuvering tests to be conducted ashore as part of the propulsion system evaluation. In this way propulsion system design inadequacies related to shaft transients can be discovered. (The propulsion system here includes the electronic control system as well as the gas turbine power train.) The

automatic load control system herein described can be applied to a wide range of shaft dynamometers by modifying the appropriate physical values.

DESCRIPTION OF THE WATER BRAKE

The specific numerical values presented in this paper relate to the water brake selected for the FFG-7 shore test being conducted at the Naval Ship Engineering Center, Philadelphia Division. These hydraulic system constants are presented in Table 1.

TABLE 1 - SYSTEM CONSTANTS

: Supply Water Pressure 3120 lb/ft2 _{1.49 x 105 N/m2}

s

Equivalent Length/Inlet Pipc 190 ft 57.91 m

Ai: Cross-Sectional Area/Inlet Pipe .785 ft' 7.29 x 10-2m2

C : Proportionality Constant .003 sec /lb-ft 6.26 x 10-5

Pi _sec2/Nm2

D: Stator Ring Diameter 5.22 ft 1.59 m

a: Stator Hole Radius .0985 ft .03 m

K: Stator Resistance Coefficient 1.63

: Ring Center Elevation 8.33 ft 2.54 m

CL

: Equivalent Length/Outlet Pipe 120 ft 36.57 m

o

A:

Cross-Sectional Area/Outlet Pipe 1.06 ft2 .0984 m2

o

The steady-state performance of the water brake is completely defined by specifying the dependent variables: water brake discharge pressure, PB, and load torque, Qu, as functions of the independent variables: entrained water weight, Wc, an

shaft speed' NB. The two families of curves, shown in Figure 1 are the graphs of these two functions (1) which may be approximated by the following equations: (9.62 x 10-12 psfg PB = W 2.3NR2 2.82 x 10= (1.84 x 10-7) 2.3m 2 B = 1.67 x 10-5 Wc "B 6-2 lb.ft N.m

(7)

Inasmuch as shaft speed is controlled by the gas turbine governor, load torque must be regulated by the mass of entrained water. _{The rate of change} of this stored water is equal to the difference between _{the inlet and outlet} flow rates' W and W , respectively.

_i

-w

Kg/sec ₍₃₎

C i o

The maintenance of cavity water temperature, Tc, below a prescribed maximum is also a control requirement. _{The differential equation governing}

is: (2.5 x

10-5

c

_pcc

T = 1.34 x 10

NBQB -ci/T+ciiT - h

..4

poc

pii

shaft power mixing ambient

heat

loss

Equation (4) states that the rate of increase in the internal energy of the entrained water is equal to the difference between the gas turbine power and the cooling attributable to the inlet flow mixing in the brake plus the ambient heat loss.

INLET FLOW EQUATION

Cooling water is piped from a "head tank" at a pressure, P., to two identical control valves at a pressure, P _{The pressure drop, AP}

, is

chargeable to losses in the piping

_systemY1

The control valves discEarge directly into a line that supplies both water brake stator manifolds. Holes in the stator manifolds provide the flow paths to the water brake cavity which is vented to atmosphere. _{The inlet flow equation resulting} from the analysis of the water brake system (1) is:

2

cvi2

-

cpwi

KIXi2

- Pm

Substituting the values given in Table 1, it becomes:

(5)

Kcal/sec

(4)

(8)

1

790 dt 2.77 x 103 dii

1.32 x

105',1 _

1.694

3 x

10-3

1231

1.0

6 supply piping pressure loss K.2X 2 1

i

control stator valve pressure

Under steady flow conditions (dW./dt = 0), with Xi = 100% and the requisite design flow = 317.5 kg/sec, Ki therefore is determined to be .275.

OUTLET FLOW EQUATION

The basic form of the differential equation governing the outlet flow rate resembles the corresponding equation for the inlet flow rate. The outlet piping system losses are small relative to the pressure drop across the outlet control valve. PB represents the water brake discharge pressure, and

the difference, (P

-AP

), provides the impetus for changes in the outlet .13

water flow rate, W. vo

2 2 Lo dW C W vo A dt = P8 - 2 2

K X

0 0

Substitute the values of Lo and A listed in Table 1. The water brake being used in the FFG-7 shore test develops a nominal discharge pressure of

4.83 x

10 N/m2 at 180 rpm while absorbing

37,250

kw. Let the outlet control

valve capacity be 900 kg/sec at this condition. The resulting valve constant, Ko, must be 0.2. N/m psfg (7) 123.2

.51

dWo dt PB {120.9} 25

6-4

X N/m2 psfg (6) (8) 1:i 2

(9)

CONTROL SYSTEM DESIGN

The results of a study of FFG-7 hull dynamics (2) provides the performance criteria for the water brake control system.

The load control system shown in Figure 2 maintains the water brake torque equal to its set-point by developing the appropriate command signals for the inlet and outlet valve positioners. The control system is designed to exploit the full performance potential of the water brake and also provide an adequate cooling water flow rate (to ensure that the cavity water temperature does not exceed its design limit).

The commanded load, QD, is compared differentially with the actual load, QD, to produce a torque error, eQ. This error is translated into a request for a change, ew, in the amount of entrained water. Inasmuch as load torque depends upon the instantaneous values of shaft speed as well as cavity water mass, the magnitude of the change, ew, required to eradicate the torque error, en, is evidently dependent upon the system operating

point. For a constant speed, N., the relationship between ew and eQ may be deduced by differentiating equation (2). Solving the result for dW , and replacing dWc and dQD by ew and eQ, respectively, it becomes: c

ew = .435 e,

QE

The control system computes a signal proportional to the quantity, ew, based on the current values of W , QR, and ecl in accordance with equation

(9) and sends the signal to the input of a proportional-plus-integral controller. This controller features rapid but range-limited integral action designed to maintain the smallest possible transient torque error consistent with avoiding

(9)

excessive load over-shoot, and to provide for short system settling P and R represent the output of the proportional and integral of the controller; their relationships with ew and t are defined by

following equations: times. components the kg ew , - 150 kg

{453.6

P(t) = - 3ew kg - 150 kg ew 1 + 150 kg -453.6 kg ew > 150 kg (10) - 1.5 ew(s)ds kg, - 90 kg ew 0 R(t) = (11) ew > 0

(10)

The controller output (P + R) is carried in parallel paths to the schedules providing the separate inlet and outlet water flow rate demands' Wid and Wod. The inlet flow rate demand is generated by a maximum signal selector which chooses either W dm and Nide. The quantity Widm is the minimum cooling water flow required for maintenance of the recommended maximum cavity water temperature. This minimum rate can be deduced from equation (4).

A nominal cooling water temperature is 27C and the maximum discharge temperature is 63C. Consequently, Widm satisfies the following equation:

1360 c > 453.6

These schedules are designed to regulate the cooling flow as a function of the measured shaft horsepower, thereby inherently limiting the cavity water

tempera-ture. The flow rate demands are converted to valve position demands for the

inlet and outlet valve positioners:

Xid = T.id; (Ps - C W

2 -

PM)-1

K p

x4 P -1

7

od Ko

o B

6-6

The selector input, functions of the controller

Widc and the outlet flow rate demand, Wod, are both output, (c = P + R): 453.6 kg/sec c <-453.6

4idc

= -c -453.6 < c 0 kg (13) 0

c>0

w = 3c kg/sec c < 0 0 < c < 453.6 kg (14) odc idm [6.41 x E3 10-2.06 x 10

NQ

B NBQS kg/sec lbm/sec (12)

(11)

Each of the set-point signals is compared differentially with the corresponding actual valve position to produce an error. This error is amplified and inte-grated to effect a change in valve position that ultimately leads to the satisfaction of its set-point. Xd and X represent the demand and actual valve positions of either the inlet or the outlet control valves which are related by the following schedule:

- 100%/sec, (Xd - X) < - 2.5%

40(Xd - X)%/sec, -2.5% < (Xd - X) + 2.5% (17)

+ 100%/sec, (Xd - X) > 2.5%

Note that if the magnitude of the difference, (Xd - X), exceeds 2.5%, the magnitude of the rate at which the valve position changes to eradicate that error is 100%/sec.

RESULTS OF THE SIMULATION

The water brake and its automatic control system were programmed on the hybrid computer system at NAVSECPHILADIV. Figure 3 depicts the system per-formance atfourimcreasing torque rates (add load). The curve labeled 100% corresponds to the torque rate required by the FFG-7 for the maneuver "STOP to FULL AHEAD". Since this curve is generated at a constant shaft speed of 180 rpm, it represents the greatest upper bound for the actual maneuver. The control system follows the desired torque curve quite well with only a slight "overshoot" at the final value. At increasing torque rates in excess of design requirements, the system exhibits an oscillatory "overshoot" and "undershoot"

which

reflects the compromise preference for short system settling times.

Figure 4 depicts the converse set of curves for various decreasing torque rates (drop load). The curve labeled 100% represents the torque rate required by the FFG-7 for the maneuver "FULL AHEAD to CRASH ASTERN". Again the actual maneuver would occur to the right of this curve in Figure 4.

Figure 5 shows a family of curves for each of three shaft speeds in which the responses to different amounts of load increments may be compared. In each case the rate of torque increase is the maximum (100%) required. The design was selected to provide good fidelity to the large load increments. Similar

families of curves were obtained using several higher initial torque values and the results were qualitatively comparable.

Figure 6 shows the corresponding set of response curves for the maximum (100%) decreasing torque rates. Again similar sets of curves were obtained for various lower initial values of shaft torque and the results were comparable.

dx at

(12)

CONCLUSIONS

No longer is it necessary to confine shore tests of main propulsion machinery systems to "steady steaming" power profiles. The automatic load control described in this paper is capable of closely following the maximum shaft loading rates in either direction that can be delivered by gas turbine propulsion systems such as those of the DD-963 and FFG-7. Consequently a wide variety of maneuvering and transient load tests can be included in the shore test agenda. For the first time, realistic sea trials of propulsion machinery can be run on land.

REFERENCES

"Design and Performance of an Automatic Water Brake Control System", Final Report of NAVSECPHILADIV RDT&E Report C-97-I.

"The Maneuvering Characteristics and Control of a CRP Propeller Driven and Gas Turbine Powered Ship", Final Report of NAVSECPHILADIV RDT&E Project C-30.

"CRP Propeller Ship-Propulsion Dynamics" Vol. 1, Feb 1971, Report 3238, Naval Ship Research and Development Center, Annapolis, Maryland 21402.

"Investigation of a Simple Form of Hydraulic Dynamometer" E. P. Calver, Mechanical Engineering (ASME), Oct 1937,

pp 749-753.

(13)

rT1 sE 5 1,1

r-P° 4 3

rn

2 1 .5 5 10 20 50 00

P8 'WATER BRAKE DISCHARGE PRESSURE ; PSIG

---0 LOAD TORQUE ; LB. FT. X 10 4

B,

1.,aii," 1111Z

.14Prig.

..111rAINIE

pprIMPIIIIpPINEE

pirP011

aPpicr

-.am=

--'

-

----

Ell

011101111111,11111'

1r

...,

--- ---. ilB

'

SPEED ; RPM TORQUE PRESSURE 180

-- co--

0 --140 --b

-4,-12 0

--*--

--x--PB -12 -9.62 X 10 W23 N 2 1 C B I 0 1. 91 X 104 P e , 8 I t

(14)

BLOCK

DIAGRAM:THE

AUTOMATIC

LOAD ABSORBING

SYSTEM

(15)

4 rrl

RPM 180

1°10

50

k

lin

100%

/

'

..._

irr

125%

r

50%

/ 1

_,

/

/,,ArAill

hull

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 TIME ; SEC

LOAD RESPONSE SENSITIVITY TO SET-POINT

RAMP RATE

*,E 100%

7:7

coz,

3IC

(16)

8 0

-4

4-4.4

-4

C:4

rn

00 20 0

\\

RPM 180

\

I

\

\ \

\

\ \

\

200%

\

1 Illg

1

i

' t150%

_Nilow-

,

° 0 /0

\

tiili\w____

....

_

0 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 TIME ; SEC

LOAD RESPONSE SENSITIVITY TO SET POINT RAMP RATE

(DROP LOAD )

(17)

A

i

-A

RPM -180

kir;

RPM -135 RPM -90

41. _rj

ii,

FA

.

AM

I

wrii

IMII

/

-/

/

100

4

80 CO .=,

.2

60 40 20

rfl

0 5 10 15 0 5 10 15 5 10 15 TIME ; SEC

MANEUVERING CHARACTERISTICS OF AUTOMATICALLY CONTROLLED WATER

BRAKE

(18)

MANEUVERING CHARACTERISTICS OF AUTOMATICALLY CONTROLLED WATER BRAKE

( DROP LOAD )

10 15 0 5 10 15 TIME ; SEC

(19)

DEVELOPMENT OF A MODERN REMOTE PROPULSION

CONTROL SYSTEM FOR THE ROYAL NETHERLANDS

NAVY GUIDED MISSILE FRIGATES.

by

Ir F.J. van den Berg, B.V. Kon. Maatschappij "De Schelde".

Ir J. Brink (LtCdr(E), Ministry of Defence (Navy).

Ir C. van der Toorn, "Fokker - VFW" B.V.

1.1. Synopsis

Hr.Ms. Tromp the first of two guided missile frigates

for the Royal Netherlands Navy completed her handing-over

sea trials June 18th 1975.

Main propulsive power is provided by a combined gas or

gas arrangement (COGOG) of Olympus and Tyne gasturbines

driving two shafts equipped with controllable pitch

propellers.

The propulsion unit is controlled by an entirely new

developed electronic remote control system.

Details of the development and lay-out are highlighted

in this paper.

Especially the theoretical background i.e. the carried

out dynamic hybrid simulation in relation to the sea

trial results are overvieuwed.

(20)

DEVELOPMENT AND ORGANISATION OF THE PROJECT.

1.2. Introduction

In

1968/69

Royal Netherlands Navy (R.N.N.) took the decision

to equip their new G.M. frigates with gasturbine-propulsion

units in COGOG-arrangement.

In connection to this R.N.N. placed an order on Y-ARD to

write the initial specification of the machinery installation

and to carry out a simulation study of the dynamic behaviour

of the propulsion unit coupled to a remote control system.

Based on the results of the Yard-study R.N.N. wrote the

final specification and assessed the lay-out of the

machinery.

At the same time of completing the specification a mock-up

was built of the ships command center, the bridge and the

technical center and in this way the optimum place of the

different push-buttons, control levers and alarm-lights was

determined.

In the middle of

1970

inquiries were made by R.N.N. at

Verolme United Shipyards and Koninklijke Maatschappij

"De Schelde" (K.M.S.) for the building of 2 G.M. frigates.

This led in

1970

to an order on K.M.S. for 2 G.M. frigates:

the Tromp and the Ruyter.

K.M.S. ordered the design and drawing work to the

Nederlandsche Verenigde Scheepsbouw Bureaux (NVSB), a

design office specializing in Navy vessels belonging to the

Rijn-Schelde-Verolme concern.

In August

1971

K.M.S. placed an order on Fokker-VFW. b.v.

for the design, construction and delivery of the remote

control of the propulsion unit for the G.M. frigates.

Nowadays "Tromp" has completed very succesfull contractor's

sea trials in March

1975.

The handing over sea trials have been carried out with

great success and to the satisfaction of R.N.N. and K.M.S.

The vessel is now completing maintenance work under

guarantee in the Yard and will be handed over to the R.N.N.

in September

1975

to join the fleet.

The "De Ruyter. will sail in January

1976

for her

con-tractor's sea trials.

The following paper will show the headlines of the

develop-ment of the remote control system whilst extra attention

will be paid to the following subjects; organisation of the

(21)

project, dynamic simulation, results of sea

trials, the set

up of the propulsion control system.

1.3. Survey of the development of the remote control system.

In 1969 Yard carried out an introductory analogue simulation

study of the dynamic behaviour of the propulsion unit to

determine the necessary control actions and the optimal

pitch rate and throttle actuator opening and closing times.

Further, the relationship between the occurring propeller

torque and thrust, as a function of the propeller speed

was measured.

In this initial stage of the project only open loop control

(steering) of the gasturbines was considered.

In order to keep certain dynamic conditions

within safe

limits, Yard introduced augmented fuel programmes to be

called upon by the operator.

R.N.N. was not completely satisfied with the results and

the way the problems were solved, the more because the

already available experience with H.M.S. Exmouth

demon-strated a bad repeatability at lower ships speeds due to

several quite important disturbances.

It appeared that the simulation of the pitch-changing

mechanism was unrealistic.

To improve the simulation on this subject and to gain more

information about the possibilities of closed loop control,

R.N.N. in cooperation with Fokker - V.F.W. b.v.,

recon-structed the Y-ARD simulation circuit.

Firstly a limited number of runs was made and the influence

of variations of the major parameters was investigated and

some experiments of closed loop control were carried out

on the analogue computer AD-4 at Fokker - V.F.W. b.v.

Towards the end of 1970 the simulation circuit was extended

to a hybrid circuit on the analogue computer A.D.-4,

connected to the digital computer I.B.M. 1130.

At the same time the simulation circuit was improved by

taking into account more recent information regarding the

controllable pitch propeller. Besides that the influence

of the cavitation number on the produced thrust was

con-sidered too.

As a result of this first part of the analogue simulation,

a new control parameter, the propeller pitch rate was

introduced.

To investigate the influence of this parameter a large

number of simulation runs were made.

Meanwhile, (in August 1971) Fokker had obtained the order

to design the propulsion control system.

The set-up of the design was already fixed in rough lines.

Input- and output modules, supply modules and telegraph

system were went from the design stage to the bread-board

(22)

From the results of the analogue simulation, Fokker and

R.N.N. determined the necessary control loops to be realised

in the control system.

Very much attention was paid at this stage to the central

test

and failure system.

Starting from a wire interruption philosophy the safe

operating sense of all the switches in the input-lines was

agreed. In this way a fail-set system was obtained.

In October 1972 the electronic bread-board system of the

pitch control loops was tested in the Lips manufacturing

shops.

To check the throttle actuator control loop a complete

throttle actuator unit was borrowed from Rolls-Royce.

As a part of the design and realisation of the complete

propulsion system and to test the function of following

items:

gasturbines and flexible mounting system,intakes and

exhausts.

main gearbox with high speed, flexible transmission

shafts, SSS-clutches and several gear-driven pumps.

the fuel supply system.

the main lubrication oil system.

the remote control system.

a complete shore trials-instruction was built up at K.M.S.

This shore trials installation consisted of half a ships

set i.e. a cruising gasturbine (Rolls-Royce Tyne), a main

gasturbine (Rolls Royce Olympus), a main gearbox and a

dynamometer, the whole unit controllable from a special noise

insulated control room.

On the shore trials the mechanical design of mentioned

items was tested. The remote control system was present

com-pletely in prototype form.

The fuel control system contained preliminary fuel schedules

based on the analogue simulation study.

Furthermore the fuel control system was equipped with the

following control loops:

- Derivative

D

- channel with dead band.

Integrating

I

- channel with long time constant.

Proportional P

- channel with limited operational area.

Extended experience was obtained with the problem connected

to the electrical installation of the control system and all

its other qualities.

All systems and their functions were tested systematically

according to a programme.

Much attention was paid to the control of the

change-over-procedure from main to cruising engine and v.v.

Starting from a system with fixed throttle actuator stroking

rates a system with controlled stroking rates was developed

and tested to reduce power and speed fluctuations during

change over procedures.

(23)

To improve the system behaviour directly after the change

over procedure and to improve repeatability in the low speed

range, a powerful proportional control loop with a dead band

was fitted and functionally tested.

Also experience was gained with the central test and failure

module and associated safety system. It became apparent

quite soon that this could hardly be missed in a quite large

electronic control system.

As a result of the shore trials some details of the remote

control system were improved and slightly modified.

Meanwhile because of the newly incorporated proportional

channel, a number of runs with the analogue simulation model

were carried out to investigate the influence of this extra

proportional control loop during manoeuvres and seaway.

In this way the optimum

setting of the gain of the

pro-portional control loop was determined.

This led from the prototype control system up to a final

design that was built during 1974 by Fokker according to a

very high quality standard for electronic systems.

In the middle of 1974 K.M.S. and their electrical

installa-tors van Rietschoten en Houwens (R&H) installed the propulsion

unit and its cabling.

In November/December 1974 cold wire checks were carricd out

by R&H and Fokker.

Thereafter, in December 1974 the Tyne's made their first live

starts followed by the Olympus's in January 1975.

At the end of January the electronic modules of the remote

control system were fitted. The system was put into service

and extensively tested.

During basin trials the right function of a great number of

systems was checked and tested, at the same time some

adjustments were carried out.

On March 10th 1975 "Tromp" sailed for her contractor's sea

trials on the date planned.

The contractor's sea trials were carried out according to a

very condensed programme.

During sea trials the fuel schedules were measured, the

change-over control system was functionally tested, the

optimum setting of P,I and 0-channel was agreed as a result

of a number of testruns.

There appeared to be a good simularity between the analogue

dynamic simulation and the dynamic behaviour and performance

of the vessel at sea.

The dynamic behaviour of the gasturbines was not completely

in accordance with the simulation.

During heavy sea motion the damping of the system appeared

to be insufficient.

The contractor's sea trials were completed on March 24th,

(24)

system were not totally finished. Complete

execution of the

program was prevented by a suddenly arising heavy seaway.

A complementary test-programme was written

for the first part

of the handing over sea trials to carry out the unfinished

adjustment procedure. Furthermore a number of measurements

were programmed to investigate the previously found problems.

1.4. Organisation of the project

Very shortly before K.M.S. placed the order on Fokker for

the design of the remote control system, the associated

analogue simulation was set up and attended by a

R.N.N.-officer and a specialist in electronic analogue simulation

at Fokker - V.F.W. b.v.

In the following stage some technical support was given by

employees of Fokker V.F.W. - ELAB.

K.M.S. were informed about the progress

of the project.

In the middle of

1972,

when the first part of the analogue

simulation study was finished, the R.N.N.

had appointed a

specialist for electronic control systems.

Meanwhile K.M.S.

had employed a mechanical specialist for control systems.

In a number of meetings between R.N.N., Fokker, V.F.W.

-ELAB and K.M.S., the final form

of the remote control system

was agreed.

In

spring

1972

K.M.S. wrote in cooperation with R.N.N. and

Fokker, an extensive building-up and

test-programme for the

shore trials.

At the same time frequent meetings were held between K.M.S.

and R.N.N. to discuss the progress of the shore trials

installation.

The necessary instrumentation was

agreed, ordered by K.M.S.

and later installed in the control room.

The shore trials took place from

August

1973

until

November

1973,

were carried out

under the supervision of

K.M.S., attended by the R.N.N.

Technical assistence was given by Rolls Royce, Fokker -

VFW

and K.M.S.

The measurements were taken by K.M.S. and the results

recorded in a report.

During the design stage

and building-up period at K.M.S.

3

men were employed with

the design and ordering of all

required equipment.

The test and measurement program

was writted by a specialist

in measurement and control

engineering. A further specialist

handled the gasturbines and mechanical installation whilst

a third had the

responsibility for the complete project, a

total of 6 men.

During the whole project 4 men of R.N.N. were concerned

with

the shore trials. One attended the building-up from

the

mechanical side, two specialised on

control systems and the

fourth responsible for the

overall coordination of the

project.

(25)

Fokker had a total

of 4 men concerned with the shore trials,

two for specialist technical assistance, one for theoretical

assistance and coordination and one for overall

responsibi-lity.

All the people that were concerned with the shore trials

have worked on the project driving the later stages of

development, until

the sea trials.

During the sea trials 3 men of K.M.S., 2 of R.N.N. and 2 of

Fokker have carried out all the tests and measurements.

Before the Tromp went on sea trials, K.M.S. in cooperation

with R.N.N. and Fokker wrote an optimum setting and testing

programme for the propulsion unit with remote control system.

K.M.S. installed instrumentation on board Tromp to carry out

the measurements.

The tests and adjustments were executed under the

super-vision of K.M.S.

Fokker supplied required technical assistance.

During the whole project regular meetings took place between

R.N.N., Fokker and K.M.S. to check progress and to coordinate

the project. These meetings will go on until

"De Ruyter"

sails

on sea trials.

1.5. Lay-out of machinery installation of G.M. frigates.

Based on the Y-ARD proposals and specification of the G.M.

frigates, R.N.N. determined the initial lay-out of the

propulsion units and auxiliary machinery.

The initial lay-out for a vessel with a displacement of

3500 tonnes was drawn in all details by the design office:

Nederlandsche Vereenigde Scheepsbouw Bureaux (N.V.S.B.)

under supervision of the shipbuilder K.M.S. and attended by

R.N.N.

During the further development of the design the

displace-ment of the vessel increased up to 4300 tonnes.

The propulsion machinery consists of 2 identical units, port

and starboard.

Each unit comprises one main gasturbine (Rolls-Royce

Olympus TM3b) and one cruising gasturbine (Rolls-Royce

Tyne RM1A)

via Metastream shafts SSS - clutches

driving a K.M.S. main gearbox through the propeller shaft

a Lips controllable pitch propeller.

At the higher ship speeds the power is delivered by the main

gasturbines. To reduce fuel consumption at lower ship speeds,

the cruising gasturbines are used.

(26)

The following main considerations have led to the chosen

machinery arrangement:

putting main and cruising gasturbine into seperate

rooms to cater for action damage.

widely separating the dieselgenerators.

providing space for removal, replacement and good

access.

providing space for easy gasgenerator exchangeability.

improving safety by choice of equipment and increased

redundancy.

selecting machinery and mounting construction in such a

way that itis shockproof and watertight up to a high

degree.

In this way a machinery lay-out was obtained as drawn in

fig. 1.1.

The propulsion unit is divided into 3 parts and spread over

forward engine room, after engine room and CPP pump room.

All these compartments are completely watertight separated

from each other and are capable of independent running.

In case of emergency, operation of the propulsion unit with

flooded engine rooms is possible.

Some of the interesting engineering aspects of the

propul-sion unit and its auxiliary systems are:

fuel supply system of the gasturbines.

The system supplies fuel from the consumption tanks to

the gasturbines via filters and filter/water separators.

The pump has an electric motor. Fuel pressure is

pneuma-tically controlled by a control valve in a return-line.

If the pumps fails and the pressure drops below a certain

level, an emergency fuel supply valve opens automatically

and supplies fuel from a gravity feed tank, i.e. the

consumption tank of the dieselgenerators.

main lub. oil supply system.

This system supplies lub. oil to the main gearbox,

Olympus power turbine & Tyne auxiliary gearbox.

The system contains a main gearbox driven pump with

variable displacement and an electrically driven pump

with fixed displacement. Both are mounted on the sumptank

of the main gearbox.

The capacity of the gear driven pump is controlled by two

pressure switches

and aaon/off control system.

The purpose of the electrically driven pump is to provide

lub. oil before the propeller shaft rotates and to cool

the bearings after shut down. In case of emergency it is

capable of supplying all the required lub. oil to port

and starboard propulsion units.

The capacity of the gearbox driven pump is large enough

to maintain a constant pressure in the lub.oil supply

system, during the lowest occuring shaft speeds.

hydraulic system of controllable pitch propeller.

This system contains a gearbox driven pump for normal

running and an electrically driven pump for emergencies

(27)

and fast manoeuvring at low shaft speeds.

The system pressure is kept above a minimum level by a

spring governed control valve and depends further on the

torque required to keep the propeller blades in the

desired position.

The propulsion unit is automatically remotely controllable

in direct mode, or in telegraph mode via the Engine Control

Centre, from Bridge and Operations Room.

Local control is possible from the emergency manoeuvring

position in the aft engine room and in the forward engine

room where telegraphs are available for communication with

the CPP pump room.

Manual remote control is only possible from the Engine

Control Centre.

Belonging to the propulsion unit there are important

auxiliary systems remotely controllable from the Engine

Control Centre i.e. pumps may be started and stopped and

valves opened and closed.

This concerns fuel supply, lub. oil supply, hydraulics,

controllable pitch propeller and seawater coating systems.

For safeguarding, alarming and monitoring several

para-meters of the propulsion unit and auxiliary machinery, an

extensive datalogging system and auxiliary signalling and

alarm system with recording facilities is installed in the

Engine Control Centre.

Kon. Mij. "De Schelde"

Vlissingen.

June 1975.

(28)

PO PO _F432 PumPROOP4

IT-17;

PumPROOM AYCRI PUMPROORT ailMeovc

_;

COOLING ENGINE - OIESF,G£NERATORROOM

ROOM AFT

-T=L:

FIG I r - MACHINERY ARRANGEMENT GM FRIGATE

11.-AO eel ZVI

L

AFT ENGINERoom roy,ydy_fin

do

rps

c.,,,z...4-4.

1 r -111110 iiimilm i

NIP

LIPLO. SePoomnft FRONT ENOMIERGTOm rug,

_,,,,,

roII

-s - 8b,ON SCHELDE .215,..iNC,EN

6-24

R10-4PROOM

HrORMILICS

(29)

THE DYNAMIC SIMULATION AND THE RESULTS OF

SHORE- AND SEA TRIALS

II. 1. Introduction

In order to design a control system for the ships

propulsion of two G.M. frigates to be built for the Royal

Netherlands Navy a dynamic simulation was carried out on a

hybrid computer consisting of a combination of an "Applied

Dynamics 4" analogue

and an "IBM-1130" digital computer.

The starting point of the simulation was that the main

propulsion engines had already been selected and it was

required to adapt the dynamic behaviour of the propulsion

plant and the ship without radical changes to avoid

dangerous situations and without influencing the

manoeuvra-bility (1).

The main purpose was to obtain results, which would be

qualitatively correct but it was also the intention to

obtain quantitative precision. However, a number of values

and the dynamic behaviour of some components had to be

estimated or approximated with the consequence that, as a

result of the cumulative effect of various inaccuracies,

the sea trial results of GMF "Tromp" differed from the

simulation results. This was recognized in an early stage.

The simulation made it possible to design a control system

with the ability to control undesirable behaviour of the

system and also to adjust optimally this control action

during sea trials. It was also possible to get an insight

into which parameters must be varied to influence, for

example, thrust, shaft torque and maximum or minimum shaft

revolutions.

During shore trials in 1973 the control system was tested

in its first design and this resulted in some additions.

The final control system was set to work on board during

contractor's sea trials. This was the first opportunity

to check the theory of the simulation because during shore

trials, the dynamic behaviour of the ship including the

controllable pitch propeller could not be simulated.

In the following sections the set-up of the simulation,

the results of the trials and the cause of the differences

between the simulation and the actual dynamics will be

discussed.

(30)

11.2. The dynamic simulation (1.3)

As already described the propulsion plant consists of two

controllable pitch propellers driven by two independent

Tyne/Olympus powered shaft sets (COGOG-arrangement). The

gasturbines are coupled to the main gearboxes through self

synchronising (SSS) clutches.

For the model some simplicifications are assumed:

the ship sails a straight course;

the displacement is maximum and the ship is not fouled.

Later on the effect of variation in displacement and

fouling is considered;

the SSS-clutches are considered as fixed connections;

because the dynamic behaviour of a number of quantities

are not known (wake fraction w, torque

coefficient KQ,

thrust coefficient KT, pitch change coefficient

CR)

the static data are used. The approximation will result

in extreme values of thrust, torque, rpm etc., which are

worse

than the actual quantities and therefore

acceptable.

The simulation model is represented in figure

11.1.

11.2.1. The hull, shafts and propellers

The

ships equation of motion is according to

Newton's

second law given by the following differential equation:

dV,

(2T - Ts)

,

where

T

= actual thrust

dt

generated by one

propeller.

Ts = ships resistance,

including thrust

deduction factor.

= displacement

in-cluding entrained

water.

Vs = ships speed.

t

= time

= sea water density.

The ships speed can be found by integration:

Vs

=

-1(2T

-

15/.UL.+

C.

L.(

The wake speed (Va), which is the velocity of the water

entering the propeller, is a function of the ships

speed (Vs): Va = (1 - w).Vs, where w is the wake fraction.

w and Ts are based upon figures found by model basin

tests.

The "equation of rotation of the propeller shaft" is

given by the following differential equation:

(31)

(Mt - Mp

P41055) ₌

27)I4

I- n414).

Hence I is constant:

(Mt - Mp

Mloss)

, where

Mt

= dynamic turbine

torque.

Mp

= propeller torque

including

pro-peller efficiency.

Mloss = torque due to

losses in gearbox,

shaft friction,

gear driven pumps,

gas turbine

in-and uptakes.

= the polar moment

of inertia of the

gas turbine

confi-guration, gearbox,

shaft and

pro-peller reduced to

shaft speed.

= shaft speed.

The thrust and propeller-torque are calculated from the

formula:

T r_ KT (0n2 D4

Mp= KQCn2 D5

, where D = propeller diameter.

The thrust coefficient KT and the torque coefficient

KQ are found from the propeller characteristics as

functions of pitch angle

_e

and the advance coefficient

=

(fig. 11.2).

nD

11.2.2. Pitch control

The pitch control is described in the following chapter.

The static pitch-command relationship is given in

figure 11.3. The error signal between demanded servo

pitch and actual servo pitch controls the electro

hydraulic control valve which activates a servopiston.

The sign of the error signal controls the oil flow

direction.

The dimensions of this servo piston are such that over

a small range from its middle position the rate of

change of pitch is proportional to the oil flow divided

by the area of the cylinder. It is assumed that in this

(32)

range the pitch changing mechanism is a first order

system with a time constant

(Tp)

equal to the time

constant of the integrator of the pitch actuating

mechanism in order to avoid discontinuity.

The pitch change rate limitation program is selected

for the main or cruising turbine. This program limits

the oil flow from the CPP-pumps to the pitch cylinder

(see section 11.3).

The geometry of the CPP-mechanism is taken into account

in the block scheme of the pitch actuating mechanism

whose output is the actual pitch angle.

11.2.3. Pump capacity

The pump capacity is a function of the pump pressure

(P ) and the pump shaft speed of the shaft driven pump.

The pump pressure is the sum of piping losses (AP), which

are a function of the actual flow, and the pressure in

the pitch cylinder (Pb). The pressure in the pitch

cylinder is a function of the blade spindle torque (Mh),

the torque due to friction (Mf = f(n2)) and the geometry

of the CPP-mechanism.

The blade spindle torque can be calculated from the

propeller characteristics from the formula

Mh = CR.C.n2.D5, where the pitch change coefficient

CR = CR(J'eact )*

11.2.4. Gas turbines

The dynamic behaviour of the gas turbines was based on

data known at that time. After sea trials it appeared

that these data were not completely correct. This

resulted in a different dynamic behaviour of the engines

as was expected.

For the G.T. simulation, the engine dynamics

_{are divided}

into two first order systems, namely for the combustion

chamber and for the inertia of the generator.

The gain and the first order time constants are

con-sidered as constants. Although these factors are not

constant, it is assumed that the influence on the final

results will be small in relation to the

_opening-

_and

closing times of the throttle, while the dynamic

character is taken into account.

The relation between static turbine torque (Mst) and

dynamic turbine torque (Mt) is approximated by the

transfer function (

K

_{K) The static turbine}

1+171s

T7e7E

(33)

torque is a function of actual fuel flow and shaft rpm

and is calculated from the turbine characteristics which

were found experimentally by the turbine manufacturer

Rolls-Royce.

The dynamics of the fuel actuator are represented by a

first order system with a small time constant ft.-.3).

The turbine torque (Mt) has to be reduced by torque losses

(Mloss) due to in- and uptakes, gearbox- and shaft

friction and gear driven pumps.

11.3. Results of the simulation, shore and sea trials

The provisional and additional control system are given in

figure 11.4.

The additional control system consists of three feed back

channels:

low speed channel to avoid unacceptable low shaft

speed. This channel is active when the shaft rpm

falls below a predetermined value.

derivative channel, which is active when the slope

of the revolutions-time curve multiplied by the

negative gain Kd exceeds the value of the dead band

of db % of the maximum fuel flow, to avoid,

to-gether with the low speed channel, an unacceptable

dip in shaft revolutions.

integrating channel to compensate for any

diffe-rence between actual shaft speed and demanded

shaft speed resulting from temperature variations,

turbine fouling and changing hull conditions.

With the simulation model as described above many computer

runs were made, starting with the Olympus, to determine a

provisional maximum astern pitch. It appeared that the

stopping distance decreased with smaller pitch angles. The

results from crash stop manoeuvres from full ahead with

the selected maximum astern pitch showed that the peak

value of the reversed thrust exceeded the specified limit

and that an unacceptable increase in propeller shaft rpm

occured due to the windmill-effect of the propeller at

decreasing pitch.

It was found that limiting the rate of change of pitch was

the most effective method of keeping the maximum reverse

thrust below the specified limit with the additional

advantage of reducing the windmill effect. From a number

of crashstops from various ship speeds, the allowable

pitch decrease rate and the propeller shaft speeds, where

the reversed peak thrust occurred, were obtained. The

allowable pitch decrease, expressed in oil flow to the

pitch changing mechanism, was plotted as a function of

the propeller shaft speeds, thus giving the "pitch change

(34)

rate limitation program" (fig. 11.5). Runs made with this

limitation program showed a maximum shaft torque above

the acceptable limit and a minimum shaft rpm which was

still too low.

Variations in opening and closing time of the throttle

revealed that increasing the opening time resulted in a

lower shaft torque and thrust, and an increasing dip in

rpm. Later on the gas turbine manufacturer required the

opening time to be increased to prevent compressor stall,

so it was to be expected that during sea trials the

torque and thrust would be lower, with a greater dip in

rpm during crash stops. Reduction of the throttle closing

time and an increase in maximum astern pitch gave only a

slight improvement in the minimum shaft revolutions.

To meet the above mentioned phenomena, a compromise was

found.

Crash stops with the cruise engine revealed an increase

in the propeller rpm above the trip speed of the gas

turbine. Whereas the reverse peak thrust was the limiting

criterion for the main engine, it was the maximum rpm for

the cruise engine, which led to a pitch change rate

limi-tation program.

With the know-how from the simulation, a control system

was developed. During shore trials in 1973 this system

was tested. The power output of the turbines was supplied

via the main gearbox to a dynamometer with a characteristic

that differed from the propeller cube law, so that a

special fuel program had to be used and no results could

be obtained from the controllable pitch range of the

propeller or from the dynamics of the ship. It was

possible to check the functional working of the control

system e.g. the start-stop-system, the engine selection

and the dynamic load transfer control could be optimised.

The main feature that appeared during this trials was a

considerable variation in shaft rpm after load transfer

from the main to the cruise engine and vice versa (2,4).

Reduction of the time constant of the integrating channel

seemed the solution. However the integrating channel has

to be insensitive to a seaway, so it was indicated that,

in addition to a smaller time constant, a proportional

feed back with a dead band was necessary in order to limit

and to eliminate quickly the rpm variations. With the

introduction of a proportional feed back there is no need

for a low speed channel.

The results of the dynamic simulation and the shore trials

have been used for the final control system.

During sea trials of G.M. frigate "Tromp" optimisation of

the various parameters took place. Analyses of the results

obtained from manoeuvres indicated that the gas turbine

behaviour was different from the simulation.

The cause of it is the fact that the time constants and

(35)

the gain of the gas turbines as well as the time constant

of the fuel actuator are assumed to be constant, but they

are dependent on the power level (low pressure compressor

speed). The variation ontthroughout the power range is

considerable and decreases at higher power levels.

r

is

maximum in the low power range because the Rolls Royce

fuel control unit is, in that range, controlled by a

relatively low LP compressor discharge pressure.

Summed up the causes of the difference between the

simulation and the actual ship's behaviour are:

the time constant of the fuel actuator is a function

of LP compressor speed (fig. 11.6).

the engine time constants and the engine gain are a

function of LP compressor speed. Preliminary computer

cal-culations revealed that using the following transfer

function (5) and an appropriate power turbine simulation

meet the reality:

_Tv.s

.e ,

where

NLp = low pressure compressor

speed.

Ke

= engine gain (a function of

speed, fig. 11.7).

e= = engine time constant (a

function of speed,

fig. 11.8).

s

Laplacian operator.

The time axis shift

( e-Ls) caused by the "dead time" is

taken equal to 1.

the throttle opening time is increased by the gas

turbine manufacturer.

the propeller characteristics are static

characteri-stics based upon model basin tests.

The consequences are:

lower peak thrusts and torques during crash stops and

slam accelerations.

lower minumum shaft rpm.

influence of seaway on the gas generator and shaft

rpm.

In the first instance the derivative channel has the

function of reducing the dip in shaft rpm during crash

stops. To increase its gain and/or reduce the dead band

is limited because the

derivative action will act against

changes in rpm demanded by command or as a result of

a

seaway. Besides increasing the gain, the pitch change rate

limitation program is chosen as a second solution and

resulted in limiting the pitch change rate in the lower

region, so that finally a constant limitation is

intro-duced. Investigations are still going on.

t

Ke

(36)

Figure 11.9 illustrates

he final adjustments in relation

to the dynamic simulation of the ship and propulsion plant

with an optimal control system.

It need not be said that the influence of a seaway at large

time constants is unfavourable and can even lead to

insta-bility if precautions are not taken to switch off the

pro-portional channel. Further analysis work on this subject

is to be done at the moment.

Conclusion

The dynamic simulation meets its main purpose to obtain

results, which would be qualitatively correct.

New information about the dynamics of the gas turbines and

the fuel control system has been obtained from the turbine

manufacturer which endorses the results of the sea trials.

With this new information and the experience gained from

the sea trials the dynamic simulation of the G.M. frigates

will be revised to reproduce the actual results in order to

get a good starting point for a future simulation.

:1.4. References

ir. J. van Sanden; Dynamische simulatie van schip en

voortstuwingsinstallatie van de geleide wapen fregatten

van de koninklijke marine; Den Haag, december 1972.

ir. J. van Sanden; Aanvullende dynamische simulatie van

schip en voortstuwingsinstallatie van de geleide wapen

fregatten van de koninklijke marine; Den Haag,

april 1974.

ir. C. van de Toorn; control arrangements of the main

propulsion machinery on board GM frigates of the RNN;

third ship control systems symposium; Bath,

september 1972.

ir. C.J. Verkleij, ir. F.J. van den Berg; rapport

wal-test BE voortstuwingsinstallatie geleide wapen

fregatten; Vlissingen, juni 1974.

G.E. Ferre and D.C. Lenkaitis; Gas turbine engine

analog simulation for acceleration sensing fuel control

studies; Society of automative engineers; Gas turbine

fuel controls analysis and design; progress in

technology, volume 9.

June, 1975.

(37)

o.1 r,

chan.Vs

rat

-Pp;

"Ptptn,

Losses 1-117P-e-Ps 1 C ftpc 1"1!,1:te4"min

t

51.0,14. E cHAP71. D 1

y IMAM LIC C00141101, VALVC

j

_{A cTUAT NG rirctiNISPI}

FIG.

-1

"Blow% 54w epir or PHYSICAL PIOEL

prora

cc

C cac -1 Ac.5 _

rectstance TS,

I cilaract'S SNIP_

j

FOWL AcTU0,TOIR Hp ; D gT

(38)

I.

-LO

Fus. 7..1.

Cepa,- onsible

pitch two

pellet

F.9.11 .3

Pi

tc.it _ Como, an

fticaion ship

6-32

K1-relaiion skip

k,

-I retatio. 11, ip

(39)

eve 4st. t

844"

GratiNg

frfkin

Pod projnort P.1:5.. i.wsh tefieseara sys 6.1.1 dIFFeret

-tiakor

T.4 HS4

Irovaiwe

cNANNEL 18.111,<

9ra tor

owtse waits

Low

fin-to

CHAttoteL

60-EGRATI4q

CHANNEL

Fi 4. Z

.4a

ADOITtoNAL CONTROL SY4

-rem

H

_{p tth-1.44. rye',}

.2\ 4

Pliedrtrakr

1.414atiVadwitas

Fic. u. .46

PorevisseAAL. conTitel sesrem

Fg

Z4

(40)

shAik

Fig

csmaGE RATE

Lim TAT,

rflog,RAm

Ftc, IL

. 6 Fun FLOW o.6sPotasE

(41)

4...pewsor

44.411

Or.]

FK, IL 7

114a E.Kour -r.sa cows1..0

raibos LP. ..ot.to-sselt

sPod

L. P. cow.pr surf ip.mi

Erfmil

Fla 31I THE

froilosi C.Atol

(42)

0Aii, attic., thrust

us-MA-44

Llacia freoewcy

MAAN EtdcitlE SLAM Ace.e

Arcot,' AND G eAiTOP

Rs- s

_{FRori SEA TWIRLS C) AbZY,WIPI}

_{%I.( ri L A "n*,4}

(43)

REMOTE PROPULSION CONTROL SYSTEM FOR THE

ROYAL NETHERLANDS NAVY GUIDED MISSILE

FRIGATES.

111.0. Introduction

The basic set-up of the system for remote propulsion

control of the G.M. frigates has been described

extensively in our paper that was presented on the 3rd

Ship Control System Symposium in Bath, September 1972,

under number III A-3.

In this paper a concise summary of the system will be

given further the new developments and the internal

safety-measurements will be highlighted.

III.1. Extend of the control system

The control system includes the following subsystems:

1.1. a push button operated fully solid state command

link which replaces the traditional lever systems

and provides on line and off line control of the

power plant from the bridge, the operations room

(0.R.) or the engine control centre (E.C.C.).

1.2. a start/stop system for remote control of the

start-, engine dry motor- and stop-procedure from

the E.C.C.

1.3. a brake control system for remote

_{operation of the}

brake which is capable to decellerate and hold

_the

propeller shaft.

1.4. a pitch and power control system for remote

operation of the power plant from several locations.

It includes programmed stepper-motor throttle

con-trol and servo valve pitch concon-trol during cruising,

manoeuvring and load transfer from one turbine to

the other.

1.5. a shaft revolution measuring

_{system per shaft that}

provides an analog feed back signal for the power

control system.

1.6. a fully redundant dual power supply system per ship

board which converts the 50V D.C. battery power into

the supplies required by the subsystems mentioned

above.

1.7. an internal safe-quarding system,

_{which can be}

activated by the several individual guards in the

control system and take the appropriate actions.

(44)

The primary task for this subsystem is to avoid

direct danger for the propulsion plant with

respect to damage and availability.

Associated but independant contributions to the G.M.

frigate project are:

1.8. a torsion meter per shaft for indication of the

power transferred to the propeller as part of the

manual propulsion control facilities.

These are our standard torsion meters based upon

straingauge bridge measurement.

1.9. additional shore trial equipment for test bed

running at the shipyard of the complete port shaft

set of the second ship in 1973.

The system is based upon specifications of Y-ARD,but has

been modified due to changes in philosophy concerning

system operation, failure modes, reliability and detailed

system design.

Furthermore hybrid dynamic simulation of ship and

propul-sion unit, testbed experiments and an extended shore

test have contributed to the development of the system.

During the recent sea trials of the first ship the

control actions proved to be satisfactory. They did

not

show up the need for a complete review of the design

principles, althoughsome minor changes have been

carried

out or are still under consideration.

The same set-up is intended for the propulsion control

system for a series of 8 Standard Frigates which are

contracted now for delivery in the early 80's.

111.2. Push button operated order telegraph system

The requirements for the order telegraph led to a

com-plicated and relatively expensive concept for a lever

system. For that reason a push button operated system

was proposed.

The basic requirement for the system was that it would

line up with the practice of lever operated

systems on

board naval ships. The actual specifications were

formu-lated in close cooperation between the R.N.N., the

Institute for Perception TNO and the systems manufacturer.

-T.2.1. Principle

The basic task for the system is to enable the user to

transmit commands and to reproduce these commands at

the receiving end in an appropriate form.

Commands are

always given in demanded propeller revs per minute.

(45)

The operator has the disposal of a panel as sketched

in fig. 111.1, with two identical halves for port and

starboard. Each half contains an array of nine spring

loaded "momentary on" pushbuttons.

Each of these buttons represents a command, consisting

of two components:

direction (ahead or astern)

demanded shaft speed.

The direction of the upper four buttons is ahead, the

direction of the order stop is irrelevant, and the

lower four buttons demand reversed thrust.

The demanded shaft speed is a fixed number of revs/min

for the buttons 1, 3, 4, 5, 6, 7 and 9.

The remaining buttons 2 and 8 activate the contents of

a memory per ships' half(port or starboard), which can

be varied by means of 4 pushbuttons "+10", "-10",

"+2" and "-2" in steps of 2 and 10 RPM up and down.

The actual contents of the memory is continuously

dis-played in numerical form at the top of the operators

panel. The "+"- and "-" - buttons can be operated,

irrespective the selected order.

The system halves for port and starboard are identical

and independent but the "+" - and "-" - buttons can be

coupled if this is desired.

The basic concept is represented in the block diagram

of fig. 111-2.

111.2.2. Organisation

The source of the orders can be either the bridge

or