Design algorithm for propulsion- and energy 'supply
systems of submarines
.July 1994
E.M. Pd
OEMO
94109II air
Ian
III.4.11
:=3.111=11
lllll HIT U Delft
Tech nische Universiteit DelftFaculteit der Werktuigbouwlcunde en Maritieme Techniek.
Vakgroep Maritieme Techniek
*0-TU Delft
Technische Universiteit DelftDe hear E. Pal Hofdijkstraat 9
1814 EC Alkmaar
Uw kenmerk en datum Ons kenmerk Doorkiesnummer Datum
1(14/1k/603 (015)75 1556 17.03.94
Damp
ondercieelVierdejaars- & ingenieursopdracht
Geachte heer Pal,
Onderwatervaartuigen worden gekenmerkt door een hoge mate van
complexiteit van de installaties. Een "Concept Exploratie
Model" (CEM) kan ondersteuning bieden in een ontwerpproces in
het voorontwerpstadium. Door gebruik te maken van bestaande
kennis, welke in het model zal worden geimplementeerd, kan
middels het varieren van diverse ontwerpparameters inzicht
warden verkregen in de haalbaarheid van een concept.
Om een analyse van een vaartuig te vereenvoudigen wordt een
functionele decompositie toegepast. Op het hoogste niveau van
daze decompositie worden de hoofdfuncties van het vaartuig
bepaald.
Uw opdracht omvat het onderzoek naar algoritmen, waarmee het
ontwerpgedrag van de componenten uit de hoofdfuncties
voort-stuwing en energievoorziening kan warden gemodelleerd.
Het onderzoek zal warden opgedeeld in twee fasen:
een vierdejaarsopdracht en
een ingenieursopdracht.
De vierdejaarsopdracht houdt het volgende in:
Inventarisatie van weerstand-voortstuwingsrelaties voor
onderwatervaartuigen. Doel hiervan is het bepalen van de
prestaties van een onderwatervaartuig op grand van een
Vermeld bij beantwoording kenmerk en datum Behandel niet meer dan ben onderwerpper brief.
Facutteit der Werktuigbouvvkunde en Maritieme Techniek
Mekelweg 2 2628 CD Delft Telefoon (015) 78 91 11 Telex butud 38151
II
_202.0,1.02
TUI
Delft
Technische Universiteit Delft
gegeven scheepsromp (inclusief roeren, appendages en
eailL voortstuwingsvermogen en schroefastoerental.
Het gewenste voortstuwingsvermogen en bijbehorende as=
toerental wordt gebruikt als invoer voor de
dimensione-ring van de Hoofd Electro Motor.
Onderzoek naar de relaties tussen de prestaties van het
onderwatervaartuig, zoals "endurance", "range",
"snui-verpercentage" en de prestaties van de componen ten ten
aanzien van de hoofdfuncties voortstuwing en
energie-voorziening, zoals het beschikbare voortstuwingsvermo-gen, de batterijcapaciteit, het opwekkingsvermogen en de
o'Hotelload" (ander verschillende
bedrijfsomstandighe-den).
De benodigde ruimte voor deze componentdn is gerelateerd
aan hun prestatie; hiervoor dienen algoritmen te worden
gezocht. Bijvoorbeeld kan worden gedacht aan het opzet-ten van een "database" met bestaande
onderzeebootdiesel-motoren, maar ook aan het gebruik van een model waarin
de dimensies (grootte, gewicht) van een dieselmotor
afhankelijk wordt gesteld van de prestaties (vermogen,
toerental).
De eindrapportage van de vierdejaarsopdracht zal 1 juli 1993
in 6-voud worden opgeleverd in een rapport in TUD-band, ander
mummer OEMO 94/09.
De ingenieursopdracht zal bestaan uit.0
Het implementeren van de eerder gevonden relaties voor
voortstuwing en energieverzorging in het kennissysteem
"QUAESTOR".
Het valideren van de resulterende modellen met bekende
gegevens van Moray- en Walrus-klasse onderzeeboten.
Onderzoek naar enkele alternatieven voor de
energieVO-dr---ziening van diesel-electrische
onderwatervaartuigen, zoals bijvoorbeeld toepassing van een
"Closed-Cycle dieselmotor" of een "High Density" batterij. De gevonden
algoritmen zullen geimplementeerd worden in "QUAESTOR".
De opdracht wordt uitgevoerd in het kader van het
promotie-onderzoek van ir. C.G.J.M. van der Nat (in samenwerking met de
firma's Nevesbu en RDM) "Concept Exploratie Model voor
onder-watervaartuigen (SUBCEM) geimplementeerd in een kennissys-teem".
Uw begeleider ir. C%G.J.K. van der Nat;
2
TU
TU Delft
Technische UnIversiteit DelftU wordt verzocht ht eindrapport (geschreven in de Engelse
taal) in 6-voud, ingebonden in TUD-band, onder nummer OEMO
94/10
voor
1 februari 1995 in te leveren.ces toewensend bij de uitvoering van de opdrachten,
CC: ir. C.G.J.M. van der Nat prof.ir. D. Stapersma sectie OEMO studentenadministratie 3 I 01.202 01.02 , U veel J. Klein Woud
A
SUB-ENERGY/SUBCEM project
RDM
TU Delft
.TEcIANOLOCGENERAL INTRODUCTION:
In the chapters II to 4 a model structure is given for the determination of
Ship resistance and propulsion efficiency chapter I
The main propulsion motor (main DC motor, MEM) chapter 2
Main batteries chapter 3
Propulsion system performance calculations chapter 4
The purpose of this project is:
The determination of parameters and relations describing the propulsion system of a
submarine, and
the implementation of the found parameters and relations in a Concept Exploration
Model (CEM).
A Concept Exploration Model is an automated approach to producing balanced vehicle
solutions, and therefore could be a useful tool to the designer in a preliminary design phase.
The design of any vehicle is a compromise between the demands of its operational role and
the physical laws governing performance. In the particular case of a submarine, the designer must ensure the hull envelope is large enough to accommodate all subsystems, however the
size of the hull also governs the power requirement and consequently the size and the weight
of the energy source, and other support systems. The systematic evaluation of
a range of
model parameters is necessary to come to a most optimum solution for a specific submarine
design.
For the CEM a computer program named QUAESTOR is used. QUAESTOR is a hybrid expert system developed by the Maritime Research Institute Wageningen that can handle a
large number of design rules and calculation methods.
With the model structure given in chapters I
to 4 its possible to determine the size of the
MEM, the main batteries, and the propulsion performance only with a few input parameters. To make the models manageable several assumptions had to be made
Chapter II The submarine is to be considered to be of a mono hull type
In the resistance calculations the yin and rudders are to be considered as foils
with their max. thickness located at 30% of the chord. The interference resistance of the masts is neglected
The propulsion efficiency (nu) is optimized at maximum continuous brake
power and considered to be constant over the total speed range
Chapter 2 : The size of the MEM is determined by its maximum continuous
power Piixant
However the mechanical strength and the commutator of the MEM are determi
ned by its maximum burst power Pi.i.hurst
Once calculated the MEM efficiency is considered to be constant over the total speed range.
SUB-ENERGY/SUBCEM project
Je
linen
RDM
The MEM is considered to be of the same construction as the Holec MEM.
The minimum mass is considered to be equal to the mass of a comparable
Siemens MEM.
The MEM is considered to be Air-cooled, with the cooling system mounted on top of the MEM.
Chapter 3 : The main batteries are considered to be of the lead-acid type
The number of main batteries and the number of battery cells of a main battery in series are defined by the user.
The open circuit cell voltage is considered to be equal to the terminal cell volt-age at 100h discharge.
Chapter 4 : The central position in the DC- system is taken by the Main Switchboard
(shown in figure 4. I). All key elements of the propulsion system are considered to be connected to this Main Switchboard.
The terminal voltage of the auxiliary systems is considered to be equal to the terminal voltage of the Main Switchboard with the main batteries in parallel. The internal resistance of the main batteries is considered to be constant during
the performance calculations.
During the performance calculations the maximum variation of the battery
dis-charge condition will be from 20% to 80% .
The propulsion efficiency is considered to be constant during the performance calculations
RDM
SUB-ENERGY/SUBCEM project
T 11 Delft
SHIP RESISTANCE CALCULATIONS IN A PRELIMINARY DESIGN STAGE
CONTENTS:
1.1. Introduction
1.2. Hull Form definition
1.3. Elements of ship resistance
1.4. Submerged Drag
1.5. Propulsion efficiency
1.6. Model structure (for implementation in QUAESTOR)
1.7. Reference list
1.8. Parameter list
ZgaAJ3
Li INTRODUCTION:
The powering of underwater vehicles is one of the important factors in the determination of
the size of the vessel. Existing power plants use a high proportion of weight and space
available in a submarine. The power requirements are determined in conjunction with speed by the size of the vessel and hence we encounter a loop in the design process where by the output of the power assessment in terms of a volume requirement for propulsion plant is a significant input to that assessment. To prevent this loop in this project the brake power will
be an input parameter defined by the user.
The maximum speed of a submarine is the a difficult and contentious aspect in any dialogue
between operator and designer. This is because it is difficult to find a logical reasoning to
arrive at a required maximum speed. It is probably one of the most expensive requirements to
meet in a design, as the propulsive power requirements for a submerged submarine of given
displacement vary as the cube of speed (v3).
There are two important aspects of preliminary submarine design - Resistance calculations
- Propulsion calculations
Three methods can be used for calculating resistance and propulsion [Kuiper,1994]1 By extrapolation from model tests results
By systematic or statistical data By flow calculations
Model tests (1) and computations (2 and 3) are often complementary, both having their
advantages and disadvantages. Model tests have the advantage that complex flow phenomenacan be simulated , but have the disadvantage of possible scale effects. Flow calculations (3) have the advantage that the flow can be calculated in detail and that variations can be made rather easily. However drastic simplifications such as inviscid flow are used in the calcula-tions.
In this paper the resistance and propulsion calculations will be based on formulas derived from systematic or statistical data (2). The accuracy of this method is sufficient enough to be
used in a preliminary design stage.
In this chapter the ship resistance (RT) , the ship speed (Vs) and the propulsion efficiency (in)
will be determined at given brake power (PH) , rotation rate (n) and ship form parameters.
Starting point of these calculations is a submarine in deeply submerged condition.
The determination of the ship resistance for a submarine in snorting condition (needed in the
propulsion performance calculations) is given in chapter 4 .
SUB-ENERGY/SUBCEM project
T Delft
RDM
2.
aft body oarallel midbody
Ii
Figure 1,.2 Submarine HUll definition
Figure 1.3 Appendage definition
fore body
outerhull
a
LBD
CAm L
prismatic coeffiCienb/c. 'The sail the rudders and the ,divingplanes can be considered as foils with maximum
thickness located at or near 30% of the chord(figure 1.3). The foinform can be described by The following variables
!era = chord length [Inl
= span [m] troll = thickness [in]
S roil = the wetted surface of he foil' Em?)
All these variables will be obtained from SUBSPACE ( a computer program for the deterfrlit-nation of the lay-out of a submarine).
SUB-ENERGY/SUBCEM
projectRDM
g@TAADCO
TUDelft
F6,11461112 HULL FORM DEFINITION (figure 1.2 and 1.3')
A submerged sUbmarine can be. considered as being build up of the following components
Hull (inclusive, added htills,for instance a superstructure)
Sail (yin)
Rudders and Diving planes
In this project the (outer) hull will be represented by an axisymmetric cylindrical body plus added hulls, which can be divided in an parallel mid-body, an elliptical fore-body and a parabolic after-body.
The (hull form can be described by the following variables: V = submerged volume (envelope volume) m3]
maximum 'height of outer hull plus added hulls [In] = maximum width of outer hull plus added hulls [m] = length over all Im]
AM = cross-sectional hull surface area(added hulls included)' fml
.= the wetted surface area of the hull [m2] The following hull form parameters can be calculated
Cb block coefficient
=
situ"
1.3. ELEMENTS OF SHIP RESISTANCE:
The resistance of a ship is the force required to tow the ship at a specified speed (this is a
condition without a propulsor).
Four components can be distinguished in the total resistance Frictional or viscous resistance
Pressure or form resistance Interference resistance Wave resistance
The skin-friction resistance is due to tangential forces acting out the body boundary.
These forces depend on the local velocity distribution at the boundary and on the body surface area presented to the flow.
The pressure resistance
or form resistance is due to the normal forces and can be
minimized by having very slowly varying sections over a long body.
When a sail (or plane) adjoins a hull, the boundary layers of both, sail and the hull
join each other. Subjected
to the pressure gradient along the rear of the sail, the
boundary layer is further retarded and an additional drag (the interference drag) arises.
When a ship moves through an undisturbed free surface it generates waves. These
waves contain kinetic and potential energy which has
to be generated by the ship
propulsion system. In terms of forces the waves result in a drag, which is called the
wave resistance.
At moderate speeds when the hull is submerged more than 3-4 times the diameter of
the outer hull below the surface, the submarine is considered to be deeply submerged
and wave resistance is neglected.
SUB-ENERGY/SUBCEM project
4.1 ;TUDelft
6RDM
TEC! INOLOG tc.esTi@olm' RT R.11 Rsail RI.sail Rplanen RI.planes 1 4 I Hull resistance:
SUB-ENERGY/SUBCEM project
RDM
T Li Delft
1.4. SUBMERGED DRAG:The total resistance is the sum of all resistances for hull,sail and planes:
RT = Rhull (Rsaul (Rplanes RI,planes)
- the total resistance of the submarine [N]
= the hull resistance [N]
= the sail resistance [N]
= the interference resistance of the sal [NJ
= the rudder/plane resistance [N]
= the interference resistance of the planes [N]
The specific resistance of a smooth submarine hull without appendages can be represented by:
CHuil = Cf ( 1 +K)
In this formula Ct. is the resistance coefficient for hydraulically smooth flat plates
(represent-ing the viscous resistance of the hull).
The formula for Coused is the ITTC 1957-formula
0.075
Cr
-(LogRn - 2)2 In which
Rn = Reynoldsnumber = V.L/u
= Kinematic viscosity seawater [m2/s]
Speed and length (determining the Reynoldsnumber) are the only two parameters influencing the coefficient for flat plate (frictional) resistance.
Hughes(see [Kuiper,1994]) took the formdrag as proportional to the viscous resistance,
multi-plying the viscous resistance coefficient with a constant factor k. The Reynolds dependent
component of the resistance thus becomes : (l+k)*C,
The factor l+k is called the formfactor and the formulafor LA( is according to Hughes:
B 0,940534 1 0,06127244 1,1395
(1 +k)=0.95 + 1,7912. 3333) Cb
In reality the submarine hull will not be hydraulically smooth. Hull roughness, safety rails,
gaps, hand rails, intercept arrays and other more or less disturbances will increase the
resis-tance. This effect is (together with the correlation between model tests and trials) represented by the allowance coefficient Ca.
7
Rt.sail)
I; k/L*1E6 AW 0.50 ia 1.00 -0- 3.00 4.00 -& 5.00 7.5 8.5 r9I 9.5 10 log(Rn)
Figure 1.4. Coefficient for frictional resistance (hull
roughness incl.)related to thee Reynoldsnumber
2.4 2.3 2.2 2.1 2 1.9 Cf 1.8 1.7 1.6 1.5 1.4 2.00 -A-8
3&7/GeDu:
In literature several methods are described to determine this allowance coefficient
- The use of an allowance coefficient of 0.0006 is recommended by the Maritime Research Institute Netherlands (MARIN){Holtackers,1991 b].
- The allowance coefficient Ca can also be divided in Sc for hull roughness and 6Ca for all other deviations.
C. = oCf +
Towsin[1983] found a formula for OCr to be added to the ITTC line(shown in figure 1.4),
which gave a good fit to ship resistance trial results:
1\
SC, = 44 - 10.(Rn) 3 + 0.115.10-3
103 L
with SC1 = the hull roughness coefficient
= the roughness height [m]
According to Holtackers[1992] the hull roughness can vary from a value of 80 micrometers (which is feasible with todays production methods and painting systems) to a value of 200
micrometer (witch can occur after some years with effects of corrosion and fouling).
In figure 1.4 a knuckle in ship resistance is observable in the speed range from maximum
speed down to minimum speed. This knuckle can only be seen if the submarine is not to
small, because of the dependency of the Reynolds number. The knuckle in ship frictional
resistance was also seen during full scale trials with Dutch submarines, and therefore
con-firmed the validity of the roughness formula of Towsin for use in submarine design.
The deviations contributing to SC increase the resistance considerably. Small appendages will contribute less to the C for a large submarine than for a small submarine due to the fact that
the amount and extent of the small appendages is not linear to the wetted surface of the
submarine. A large submarine will have relatively smaller appendages. According to
Holtackers[1992] the value for SC, is approximately 0.10 l0 for a large submarine and 0.50
le for a small submarine.
Trial results with the Dutch submarine Walrus gave a value of 0.0002, assuming a value
of 0.0006 for the total allowance coefficient (C) leaves a value of 0.0004 for SC..
( 1 1 C, 44 (1c ) , 10(Rn) 3 + 0.115.10-3 + SC. a 103 L
in which &Ca has an initial value of 0.0004
All together the specific resistance coefficient of a submarine hull can be represented by:
= Cf * (l+k) + C.
The Hull resistance(R11) is found by multiplying the non-dimensional specific
resistance(C11) by 1/2.p.Vs2.S1,,,.
SUB-ENERGY/SUBCEM project
TUDelft
8)
So:
1 2
RHull 2.P.vxis +k).Cf + Ca
In which p = specific mass of water [Kg/m3]
Vs = ship speed [m/s]
Sum = wetted surface of the hull [m2]
1.4.2.Sail-(yin-)resistance:
The specific resistance of a smooth submarine sail can be represented by:
t4. tf 4 =Cf,stul' 1 ÷ 2(. 11-)
+ 60(c±) )
SUB-ENERGY/SUBCEM project
TUDelft
Cfoil Cfod [1-loerner,1965] 9 In which t i = maximum thickness [m] = chord lengthIn this formula C1.(2.t/c) is the resistance coefficient representing the viscous resistance of
the sail.
Because of the thickness(displacement), the mean average velocity around a symmetrical foil
section is higher than that of the undisturbed flow. This results in an increase of resistance
roughly in proportion to the thickness ratio (tic).
In addition to the viscous resistance, there is also a certain form drag. This
pressure-orseparation drag component can be represented by C.,..,,,1.(60(t/c)4). In this equation (tic)'
repre-sents the frontal area on which the pressure is acting,
and (ea
represents the effect of theadverse pressure gradient along the rear of the section [Hoerner,I965].
The value of Cr to be used in the formula is the same as for a thin flat plate:
0.075
Cf
(LogRn - 2)2
In which Rn Reynoldsnumber
(=VIA))
with L = chord length c [m]
The sail resistance (R1) is found by multiplying the non dimensional specific resistance by
1/2.p.Vs2.S1. So
=
RDMi
Maygixn
SUB-ENERGY/SUBCEM project
jJ.41,TUDeift
10RDM
Rsail . s2,Ssail'c
f,sair te + 2(-=2=) Cfoil + 60(tf61 cfoil /In which = wetted surface area sail(= S11)
with S1
= span[m]
1.4.3.Interference resistance:
Where the sail adjoins the hull, the boundary layers of both, sail and the hull join each other. Subjected to the pressure gradient along the rear of the sail, the boundary layer is further retarded and an additional drag (the interference drag) arises. This type of drag is independent of the span of the sail.
According to Hoerner[1965] the interference drag coefficient is therefore most suitably based
on the thickness area01,12)
1 2 2 tfoil
R%sal.1 = 2.p.V .tfoil. 0.75(--) - 0.0003
Cfoil thii)2
Cfoil
1.4.4. Rudder/plane resistance:
The rudder and the plane resistance are calculated in a similar way
as the sail resistance.
1.5. PROPULSION EFFICIENCY:
The power required to tow a boat is found from:
PE = Vs'RT
Here is the Effective Power in [KW] and R1 is the total
resistance of the boat without propeller.
For a boat with propeller the energy output is RT.Vs. The
energy input is the delivered power
at the propeller (P,)=Q.27-c.n , with Q = the torque measured at the propeller shaft)
So the propulsion efficiency is:
RT.Vs 1D
27u.n.Q
=
6:;,7_/GR)w
This efficiency can be divided into parts which are related to
the propeller performance without the hull and to the hull with propellerRT. Vs R. Vs T.Ve Qo
D
27.n.Q T.Ve
27.n.Q0 Q
In which:
(=(RT.V,)/(T.V,)) is the hull efficiency. This efficiency can be expressed into the
Taylor wake fraction(w) and the thrust deduction factor(t) by writing:
RT.V, T.(1 -t)Ns 1
T.Ve T.Vs.(1 -w) 1-w
The thrust deduction is typically smaller than the wake fraction, so the hull efficiency
is larger than one.
rio (=(T.V,)/(27t.n.Q)) is the open water efficiency. This is the efficiency of the
propel-ler in the mean inflow V. It can be derived from open-water diagrams of the propel-.
ger;
flR (= Q/Q) is the relative rotative efficiency. This efficiency reflects the difference in
torque in the wake and in open-water at the same thrust. The relative rotative
efficien-cy is generally close to one [kuiper,1994].
The product of the propeller open-water efficiency(ri) and the relative rotative efficiency(1)
is called the propeller efficiency in behind condition(ih). This propeller efficiency in behind
condition tends to move in the opposite direction of the hull efficiency
when the wake fraction changes.The propeller efficiency(nb) will always increase when the propeller diameter increases and
the propeller shaft speed decreases. However, part of the increase in overall propulsive
effi-ciency will be lost due to a decrease of the wake fraction when the propeller diameter
in-creases.
For the same power, a lower shaft speed requires a higher torque. The available torque is
limited by the available space in the aft ship for the Main ElectricMotor(MEM).
1.5.1. Propeller-Hull interaction:
The common position of a propeller is behind the ship hull. Before a propeller can be
de-signed from open-water diagrams it is necessary to estimate the interaction between hull and
propeller.
In this preliminary design stage this will be done using the
wake fraction and the thrust deduction factor.SUB-ENERGY/SUBCEM project
RDM
TUDelft
a.. --t
c. (NOLOGIMW/GObA
SUB-ENERGY/SUBCEM project
TUDelft
12
The following assumptions will be made:
The nominal wake fraction is the same in the propeller plane (where it is mea-sured,or calculated) and in a plane several propeller diameters upstream of the propeller plane.
The nominal wake distribution in this upstream plane is not effected by the
propeller action.
The wake is uniform over the propeller disk.
For the propeller entrance flow the nominal wake fraction(w) is used:
Ve=Vs.(1 =NV)
In which: V = the entrance velocity in the propeller disk [m/s]
The thrust to be developed by the propeller should be greater than the resistance without
propeller at the design speed. The thrust has to be equal to the resistance of the ship including
the effect of the propeller on the hull. The main effects are:
An increase of the velocity along the hull (generally a small effect). A decrease of the pressure around the stern.
Both effects will result in an increase of the resistance, this is expressed in the thrust
deduc-tion factor(t):
with: T = The thrust to maintain a certain speed
[KN]
= The resistance without propeller at that speed(as found from the resistance
calculations) [ K N ]
In the preliminary design stage some estimates have to be made to predict the thrust
deduc-tion factor and the wake fracdeduc-tion.
The calculations of wake fraction and thrust deduction from statistical data and from flow
calculations are still in their infancy [Kuiper,1994]. a.,
a, b..
L&E/GeDT.ki-,A
SUB-ENERGY/SUBCEM project
T Li De I ft
An approximation of the wake fraction is given by [Holtackers,1992]:
W=
wI = CI +
0.919.E
if D W2 = 0 f w2 =f1(1 w1) if 13 f1 = 1.065.(0.7 -
- 0.038With: Dp = propeller diameter
IC] = 0 for submarines with "X" rudder configuration (shown in figure
1.5)
= 0.09 for submarines with "+" rudder configuration
The thrust deduction is even more susceptible to the shape of the afterbody and the rudder
configuration than the wake fraction. The reliability of statistical formulas is therefore even
less.
Following Taylor[1910),Holtackers[19911 gives a rough approximation of the thrust deduction
factor:
t =0.41.w
The hull efficiency(Th) can be found from:
1-t
rl H
- 0.41 +
0'591-w 1 - w
1.5.2 Propeller design requirements:
The open water diagrams of the Wageningen B series (figure 1.6) can be used for a
prelimi-nary design of a propeller. To be able to design a propeller the requirements
should bedefined.
The propeller is designed for a given speed (an initial speed which is later adapted based on
power):
Using the wake fraction(w) the propeller entrance velocity(V) is known.
The resistance of the hull without propeller should be determined from the resistance calculations. K-1-.4.1.10101 .TEC1111 ",. >- 0.7 0.7 +
10Ko 110 1 4 1 3 1 2 11 10 0.9 08 07 06 05 04 03 02 01 IS =4= 1,4-1 "" 1: 1/1=1/11111311 ramie PMESEELM, "" Itt=t===... trs " .441C11211:: rma ma :IIRMEEIEELH31" :: i..,... HEIM: .. HitIllt 1
t .2.1r1R/HIPAMPPRiiiiiMMIlih 11/11/19E1
...raigitir
. ttikahtlitte.:=IIPiiH215P VilliHrthlill.ARFORMINN AMMOENIMMMIN
fft=raiiiirealhrjfr
= r : . . . .- .- ..r. r. -, .: = r ****
tal..E.:Malffitt:71::11 ..:= ..U. L..
Ef.t: ;TA li 11411.liW1412.;11011:42.11.11.1dE11271:JI43:triLELFHit F."'1133212=":14IP
m::=:MEEE:Eitli.. , ..,... -- E: Ill EilliWIMIIM iiiii -1:111 * Ili
ftrSi*
I 1 Wilk. . i i 4...ttl1110t
1 1 lam mumilli, Pi :NM :-"-E -:-H1==.6-
- r4,1,-.1.4=-==.-4.,169pain...inici-al,,,.=ciarEmstaiiimiiiiiraiffii.-_-:-hArgish unii flIffflfl :=.=
:...-74: **m--m.illie. gikee=:::: :ti I NSF
. :.=mr
...rina,=.:::
iii:....7.
new:.:4
:I ... .. ...i,... Milm-..r..-..
MEM.T.T.Mir indihi411. ii iin Tasimig,sii._ , :pahnimish.u: -a_
...=,,E ..-=:.,=p....,_=1._..,...,==a== ..- =,,E=n:: i.. ..:=nesmn....,,
LEHLonkeeLmLt----:-.=:,..1#4.1:41HIEE::::::7-tr'..WIER-110,1411reVirdliirM ilmo.rg,"9'"i.Ir
.... Et 211-,-.----,::mr:--:-;::=:. ---:?: -' - :;.-4 '''"-* - -:emn-'= = ' ,W..-.. 1.149MM:11711..7,11104W.Wir...Tdit:,41 t. r-- m := .7* -- .... t.7_7.. ...m. .. .. ..,.m.L...m,,,...le.,...,...=..,..,p2p,,...==-, -. -...===:-.... 41=---7:4124-11111.1 m-_q=2RE t--.4T4ifoairrtildVielirq
211Pdfilig-t-..T:-..:1-7:2=4 tr. ...py.w....,410,44,,.,tityF7.4 zfiF_ =! , ,--,..-... if :env e. -El ha: o .. 00.111MEMMIPin 0.69. rkr4-.4,_1111111.=k-nalt "Fa piK.15:1Ltv.I.= ,46711-4 :Tat =.41- np 14=4 va.71, FAR9AigeliiiiMP1TALIPL":1:14010:g110;: 01 02 03 04 05 B 5 - 60Figure 1.6
The WAgeningen B- propeller series
B 5-1051 5 7 51
5-60: 5-45i
1 2
Curves for optimum diameter of five-bladed
B-screw series 13 1.4 1.6 1973 06 07 aaj 09 1 0 0 II 8, I
-a
H
SUB-ENERGY/SUBCEM project
TUDelft
Using the estimated thrust deduction factor(t) the required thrust can be found
from:
14
The propeller designer now has to choose: Number of blades(Z)
Blade Area rat i o ( A Elk)
Rotation rate(n) or propeller diameter(D) Choice number
of
blades(Z)The number of depends on:
Common harmonics of engine frequencies Structure of the wake
Importance danger tip cavitation
Weight
Blade Area ratio(A
)
The blade Area ratio is chosen such that cavitation is avoided as much as possible. The blade
Area ratio for submarines is often close to 0.6 [Holtackers,I991]. Rotation rate(n),/ propeller diameter(D)
The maximum rotation rate is determined by the MEM. The propeller diameter is limited to
0.7 *B (with B= the maximum width of the outerhull).
After these considerations the charts of the B-series can now be used to design a propeller
with maximum efficiency within the design restrictions.
The propellers of the Wageningen B-series are indicated by their blade number and blade
Area ratio for instance propeller B-5-60 has five blades and a blade Area ratio of 0.60.
The following parameters of the Wageningen B-series propellers have been varied [Kuiper
,1994]:
The expanded blade Area ratio(A,,/A) from 0.30 to 1.2 The number of blades(Z) from 2 to 7
The pitch ratio(P/D) from 0.5 to 1.4
In all cases the entrance velocity of the propeller(V) is assumed to be known. When this is
not the case it has to be estimated and optimized later.
When the delivered power(P0) and the rotation rate(n) at which this power is developed is
known. The unknown variable is the propeller diameter(Dp).
When a parameter is unknown it is possible to eliminate this parameter from the diagram
instead of optimizing it by variations.
For instance the propeller diameter can be eliminated from the diagrams by plotting KQ/.15
versus Ills, instead of KQ versus J.
RDM
NAGEN.INGEN B-SERIE PROPELLERS
PUBLICATION:REPRESENTATION OF PROPELLER CHARACTERISTICS SUITABLE FOR PRELIMINARY
SHIP DESIGN STUDIES, INTERNATIONAL CONFERENCE,
COMP6TER APPLICATIONS OF SHIP YARDS OPERATIONS AND SNIPDEBI",
TOKYO, 1973
.BY
4.1L.AcC. OOSTERVELD EN R.,00SSANE10.
-NO CORRECT:ION FUR TIE KTAND KO VALUES
:NWliT DATA:
NumBER OF PROPELLER TOCLuTiONS PER MiNIT NS= 200.0
CTARETER PROPELLER "N m D= VARIABLE DURING OPTIMALISATIONI EXPANDED BLADE AREA PAT.) ... AE/A0= VARIABLE DURING OPTIMALISATION OlAmETER-PlICR RATIO PP/Dr VARIABLE DURING OPTIMALISATION
KimBER OF PROPELLER B_ADES 08= 5 S7iP3PEED IN KNOTS VS= 20.00
HAVE FRACTION NUMBER PSI= 0.3100 PPOPELLER POoER IN go , P= 4100.
CENTER PROPELLEREmAFT 73 NATTERLINE IN N DEPS= 10,00
sTICTOR g :N THE :,ANI74TICIN CR:TER. 40F'M KELLER = 0.15
RELATIVE ROTATIVE EF7iCIENCy RRE= 0.980r ,,b
P li pi 7 A. AAGEN1NGEK B-SERIE PROPELLER
°PIMA COEFFICIENT OF ADVANCE 18.94 t BEFORE TOPVALUE OF EFFICIENCy CURVE
NUMBER OF PROPELLER REVOLUTIONS PER AIN'T iNS=
DIAMETER PROPELLER IN A D= 3.61
EXPANDED BLADE AREA RATIO AE/AO= 0.5252 DIAMETER-PITCH RATIO PP/D= 0.8727
NUMBER OF PROPELLER BLADES APB= 5 SAIPSPEED IN KNOTS VS= 20.00 PROPELLER THRUST IN N T- 344543.
PROPELLER TORQUE IN NM .12= 195761.
PROPELLER POWER IN KW .P= 4100. PROPELLER EFFICIENCY ETAO*ETAHoETAR= 0.597
Figure 1.7" Example of a computercalculation of the Journee
program
SUB-ENERGY/SUBCEM project
;I..,
Ti.UDelft
1.5.3 The rotative efficiency
The relative rotative efficiency reflects the difference
between torque in the wake and in
open-water at the same thrust.
For single screw submarines the
relative rotative efficiencyvaries from 0.95
to 0.99[Holtackers,199111Stierman,1985].
So a value of 0.96 for the relative rotative efficiency will be a good approximation.
1.5.4. From delivered Power(P0) to Brake Power(P0
Going from delivered power to brake power, the mechanical losses have
to be taken into
account:
PD m*PB
With : = the mechanical efficiency
The range for mechanical efficiencies(or shaft transmission efficiencies) as usual for
subma-rines is not very large. From a value of 0.98 for a direct drive from an electric motor to the
propeller down to a value of 0.96 for a shaft line from a turbine to the propeller including a
gearbox seems to be reasonable(for the design speed).
15
Based on a similar idea is the computer program named "Jounce" (or B-prop) which is used
at the Technical University Delft. This optimization program is based on the B-series
polyno-mials given in [Oosterveld,1973}.
For a given set of parameters Pi, , n , Z ,
V. w
, t and riR this computer program calculates:rh, the propeller efficiency
D, the optimum propeller diameter [m]
AdA the expanded blade Area ratio
P/D the pitch-diameter ratio
T the propeller thrust [N]
example of a computer calculation of the Jounce program is given in figure 1.7.
With the calculated propulsion efficiency (rm) and ship resistance (RT) the ship speed can be obtained from (figure 1.8)
Vs RT An :
RDM
INcloca,submarine
form
parameters
Resistance calculations
wake fraction calculation PD =m.P11
t = 0 . 4 1 w
"Journee"
Figure 1.8
Modelstructure Resistance and
Propulsion
calcu-lation
IPP
LagEK-ADTYr:4_,Is
T ti De I ft
1.6 Model structure (for implementation in QUAESTOR)
The model structure used for the resistance and propulsion calculations (in submerged
condi-tion) is given in figure 1.8.
The model will determine the ship resistance R.I. and will optimize the propeller diameter
Dr, and propulsion efficiency r given maximum continuous brake power P11 with
corre-sponding rotation rate n and ship form parameters.
Starting point of the resistance and propulsion calculations is an initial propeller diameter (Dr) and an initial ship speed (Vs).
Figure 1.9 shows the total
coefficient for frictional resistance (Cr + 6C1. )related to the
Reynolds number (Log(Rn)) together with the working area of the CEM.The working area of the CEM is hatched.
Ship lengths - 40 - 70 [m]
Ship speeds - 12 - 20 [knots]
Hull roughness - 80 - 200 [p.m]
In this working area the frictional resistance related to the log(Rn) can still be considered a
straight line (at a given value for Hull roughness).
However at lower values of the ship speed, for instance during the performance calculation,
the
ship speed may be less than 10 knots, and the working
area could pass the knuckleshown in figure 1.9 . In that case a little difference is to be expected in the value of the
(opti-mized) propulsion efficiency used in the calculations and the actual efficiency.
16
SUB-ENERGY/SUBCEM project
RDM
TE iNIOL G
2.4 2.3 2.2 2.1 2
Cr1000 1.9
1.8 1.7 1.6 1.5 1.4(including roughness allowance)
log(Rn)
Figure 1.9 Coefficient for frictional resistance (hull
roughness incl.)related to the Reynoldsnumber
with working Area CEM.
k/L*1E6 "1E0.50 JD- 1.00 2.00 -0- 3.00 -AT 4.00 -& 5.00 7.5 8 8.5 9 9.5 10
slk; RhT/GeDimc3
SUB-ENERGY/SUBCEM project
TUDelft
17 1 7 REFERENCE LIST Hellstrom, 1988S.A. Hellstrom:"Submarine design-Hydrodynamic aspects", paper no 18 in "Warship
88/International symposium on conventional Naval Submarines": The Royal Institution of Naval architects.
Hoerner, 1965
S.F. Hoerner:"Fluid dynamic drag"; Koerner Fluid dynamics.
Holtackers ca., 199Ia
J.G.F.M. Hohackers; D. Stapersma:"Analysis of Submarine Powering", Report MO
E0512.808;
NEVESBU
Holtackers, 199Ib
J.G.H.M. Holtackers:"Weerstandberekening van onderzeeboten deel I":
NEVESBU
Holtackers e.a., 1992
J.G.H.M. Hohackers; D. Stapersma:"Low Resistance and High Propulsive Efficiency
of utmost importance or not?",
NEVESBU
Kuiper, 1994
G. Kuiper,"Resistance and Propulsion of ships", Report 874K course MT512;
TU Delft.
Oosterveld, 1973
M.W.C. Oosterveld; P. Oossanen:"Representation of propeller characteristics suitable
for preliminary ship design studies";
International Conference,Computer applications of ship
yard operations and ship
design,Tokyo.
Stierman, 1985
E.J. Stierman:"Resistance, Propulsion and Flow visualisation tests for modified
Wal-rus", Report no 45380-3-DR/VT,
MARIN.
Taylor, 1910
D.W. Taylor"The speed and power ofships ,Ha manual of marine propulsion";
Wiley, New York.
Towsin,1983
RI.
Towsin:"Ship design for fuel economy, Bottom condition and fuel conservation";8th West European Graduate Education in Marine Technology School, Gothenburg.
SUB-ENERGY/SUBCEM project
ZW/G&M
TUDelft
1.8 LIST OF PARAMETERS
AE/A = The propeller blade area ratio
Am = The cross sectional Hull surface area (added hulls included)
= Max. width of the outerhull (added hulls included)
Clod = Chord length of a foil
Ca = The allowance coefficient
SC0 = The allowance coefficient excl. Hull roughness
= Block coefficient
Com Drag coefficient for a smooth circular mast
Cf The specific resistance for hydraulically smooth flat plates
SC, Hull roughness coefficient
Cf,sail The specific resistance of a sail considered a smooth flat plate
Ci Specific resistance of the Hull
Cp Prismatic coefficient
The specific resistance of the sail
Max. height of the outerhull id. added hulls
Dp The propeller diameter
Dp,opt The optimum propeller diameter Fn The Froude number
The non dimensional advance ratio The acceleration due to gravity The Hull roughness height
KQ = The non dimensional torque coefficient
= Length over all The rotation rate
P/D The propeller pitch/diameter ratio
PT, The delivered power
The effective power
The torque in the wake of a ship
Q,, The torque in "open water" condition
RH un The Hull resistance
RI.plane = The interference resistance of a plane/rudder = The interference resistance of a sail
Rn = The Reynolds number
Rplane = The plane/rudder resistance
Rsai, = The sail resistance
= The total resistance of a ship
Sllull The wetted surface of the Hull
= The wetted surface of a sail = Span of a foil form
= The thrust
The thrust deduction factor troll Thickness of a foil form
Speed of advance
The entrance velocity in the propeller disk
v, Ship speed
The wake fraction
The number of propeller blades
18 = = = = = = = = = = = = = = = = = = = = RT = Ssail it = = = = = = =
SUB-ENERGY/SUBCEM project
V.) Delft
= Form factor in ship resistance calculations = Submerged volume (envelope volume) = Kinematic viscosity of seawater
= The specific mass of water = The propulsion efficiency = The Hull efficiency
= The mechanical efficiency = The "open water" efficiency = The optimum propeller efficiency = The relative rotative efficiency
19
RDM
I NOLOG4k
SUB-ENERGY/SUBCEM project
TUDelft
2 DESIGN ASPECTS OF A PROPULSION MOTOR
2.1 CONTENTS
2.2 Introduction
2.3 Determination of the MEM diameter
2.4 Determination of the MEM length
2.5 MEM Cooling system
2.6 MEM efficiency
2.7 MEM-mass calculation
2.8 Model evaluation
MEM dimensioning model
2.10 Reference list 2.11 Table of variables 2.12 Parameter list 20
RDM
TE C 1OLOG Y4:
IMM
4,.---4vristatit
-, , -
(.r-,,... ,
1-is _..1 i\
111 isA ; 4.a...L.: -,a-..i 1
\
''7-35-F--r--,..--r
+i. . - .-is.;
ri
t
e z
: : A
,--.4. ..,,". .-1.1.4...___.. -,... we
(
_...ttil.e.11.A. .1.i..,.7.,...,3W. AFit. ;,..ti.. .7,,,59 ..zit.:-:,...t,it!
.lire
-I
-am'
Picture 2'.1 11-10LEC DC main propulsion motor
oil
Propulsion Motor 3700 kW. 200 rpm Open Loop Air - cooled, 2 Armatures Manufacturer Siemens Nurnbergk
isla
raft
-r 7c
.411Holec DC main
propulsion motor for Dutch submarines.
Double-armature
motors are specified
for Me new Walrus class and the Taiwan Navy's Hat Lung class
Propulsion Motor 6600kW. 200rpm, Closed Loop Air -cooled, 4 Armatures Manufacturer Siemens Nurnberg
2 2 INTRODUCTION:
In this chapter we will consider a Direct Current (DC) electric motor with the rotor directly
coupled to the propeller shaft. The electric motor is dimensioned to deliver the shaft power
determined at the top speed of the submarine.
High propulsion efficiency calls for a large diameter and low rotation rate (rpm) propeller with high torque (as explained in the previous chapter). There are however limitations of the field of an electric motor that can be generated on the gap between rotor and stator, and the circumferential force that can be generated on the rotor. The requirement of the propeller of
high torque and low rotation rate will require a large diameter rotor leading to a heavy,
volume consuming propulsion motor at the narrow part of the pressure hull stern.A possible alternative is the use of two or more smaller motors on the shaft, this trades
diameter demands for additional length demands. This configuration may be adapted becauseit provides some redundancy to the system and it can allow changes in propulsion at lower speeds.
Though sized for full power the propulsion motor will spend most of its working life at much lower powers and shaft speeds.
Deleroi [K,1993] has determined a series of formulas, in which the dimensions of a DC main
electric motor (MEM) were related to the performance of the
MEM.It appeared to be
possible to design
a MEM on
baseof a few given
parameters (delivered power,voltage,maximum current and rpm). All other design parameters are defined, based on
DC-current design knowledge.
SUB-ENERGY/SUBCEM project
TUDelft
Zit
,
rotor mtxtor yoke thain Dole interpole \, a Da
Figure 2-1 Determination
or
theMEM diameter
iusulildom enductor
Figure 2,2 HEM rotor slot
conductor 'slit
<5'
1
117 S A
Rbw®&rai 3 D.= PB 4.p
n
1MENC713-cc lalCu,a'hN86SUB-ENERGY/SUBCEM project
,!.t=TUDelft
2.3 Determination of the MEM diameter
Figure 2J shows a characteristic cross section of a MEM. The MEM 'diameter as given
D'MO = D + 2 Elt a
+ 2.h
+ 2' h.
with D = the rotor diameter
= the airgap thickness (m]
h. = the pole height on1
114 = the height of the stator yoke. ,[m)
2.3,1 Rotor diameter
According to [Deleroi,K 1993] the rotor diameter of a MEM can be expressed as a function
of the following parameters
D. =fri(PB,Zen,iihorm,,,p, a ,J.,Ica,,a,,hro Bo)
In whichv PE, = brake power = fl. U1..10 [WI
U
= maximum terminal voltageivi
= maximum current [A]l
Z. = number of MEM armatures,
nmrim = motor efficiency
= number of revolutions Ws}
= number of pole pairs, = pole Area ratio
= armature current density '[A/rn?]
= armature winding space factor = height of armature slot
BaL =.mean .aitgap.Mduction. [111
The function fl is given by the formula,:
The values of the parameters p ,a
, J , hN and B8 are given in § 211. These valuesare based on design knowledge. So the only variables in this formula are PB, Z
, n
, andimum. The values of PB, Z. and n are given but in this stage the MEM efficiency is unknown.
An initial value of 0.95 for the efficiency of
a DC-current MEM seems to be reasonable[Deleroi,K 1993]r by [ 6
a
[m] 22 ':t11(1: TE C I-INOLOGMg7_/GObil
The rotor diameter is limited by a maximum allowable circumferential velocity (Va) of 25
[m/s]
25 D
a
2.3.2. Airgap thickness
The thickness of the airgap(o) is related to the airgap induction and the number of
ampere-turns.
= f2 {B6 , (If .
wf)}-with wiT) = number of ampere-turns
If = exciting current
number of exciting windings
Hopkinsons principle gives
TUDelft
23
SUB-ENERGY/SUBCEM project
RDM
with field magnetic constant (= 4.7r.10-7 [Him] )
The number of ampere-turns can be written as
Jo
(Ifw) =-2101,a . CC
Tx
in witch b, = slot width (shown in figure 2.2) D111
TN = slot pitch [m]
= pole pitch
According to [ Deleroi,W1993] the slot width can be determined by
7t
/- 7
/<,
//
/
,/
/N\/
//
/
/
/
/
/
/
//
Figure 2.3 Construction of a main pole
winding
0_
.yoke
(X (6"p
Figure 2.4 in pole winding
I
/
/ /1
./
. ill I,/
/ 'II/
/
'/
/ I II/
I/
,
, bps-- rt'
.1 cc.
./.1-24-t/
1/
"-IP/
/
1 bnv /
. *1/I.
/! 1.
pole mhoc! fie a wiading
-/
/
/
a
/
with
8. p. Bo
2.3.3 Poles
Figure 2.3 and 2.4 show the construction of the main pole with pole shoe and Windings.
The field magnetic flux of the pole core ( (1)p) can be written as a function' of the magnetic
induction and the surface area perpendicular to the flux
4)p =bp.lp . Bp
=field magnetic flux of the pole core
=pole width
= pole length = pole induction (= and
4)p = bps lps.Ba.kst
With bpn = pole shoe width N Tr, XX
= pole shoe length (= lp )
-Nlo = stray factor (=1L2 )1[Delerot,W 19931
24 slot pitch can be written as
t .2.p
TN
-
PNwith N := number of slots and
2.It D
N - a
hN
So the thickness of the airgap cantle calculated with the formula
D.
kcu,pSUB-ENERGY/SUBCEM project
RDM
4,4TUDelft
[ml[ml
. -bp 1.1 [T1) ) [m] [m]Figure 2.5 Cross-sectional Area between rotor and stator
yoke
Wesw@cipm
With the combination of both formulas the pole core width (be) can he determined
BA
st
.a.r
p Ear p
j-113
The pole height (hp) can be calculated from the occupied cross-sectione area between rotor
and stator yoke(figure 2.5). For reasons of symmetry only a segment l/(2*2*p) of this
cross-sectional area has to be considered, the area of this segment is called Areal
1 IT
Meal
-2.2.p 2 - (DL +2 . 8)2) 4with = inner diameter of stator yoke
= pole height 1mi and Dj =Da + (2.8) +(2. hp) Substitution Reads to hp2i Areal - 'Tr .((Da +2. )l.h.p + 4.p '
Areal consists of one half of the cross-sectionall areas of both pole and interpole and some
free space (cooling air space).
So Areal can also be represented by Area2::
(Qp6hp 1 + Qw43 +
lAp)
2
bpArea2=
with airfactor ( with an estimated value of 0.6)
= interpole winding Area
Ap = cross-sectional Area of the inlerpole core
Q,4, = pole winding Area
Ap = cross-sectional Area of the pole core
-SUB-ENERGY/SUBCEM project
4434,TUDelft
25RD111
e K-45" :rill:la'. '111\ 61., TECI INOLOCa b [m] Area2 -k = [m2] [m2] [m2]Interimle Winding Area (0,,hp)
Assuming that the amount of copper of the interpoles is equal to the amount of copper of the armature [Deleroi,K 1993] we find
Iccua Ja hN.D.Tt
)
P kv,p Jw 8 . p
in which J = current density of stator winding (= 3 [A/mm2] )
k,e4, = space factor of the stator winding (=0.6 )
Cross-sectional Area of the intetpole core (A hp)
The cross-sectional Area of the interpole core can be described by its height and width
Ahp = bhp hp .bhp
with hIT = height of the interpole = hp [m]
bhp = width of the interpole [m]
According to Deleroi [K,I993] the width of the interpole is equal to the slot pitch (TN). We already found that
Together with the formula for Tr
D.it
a T -P 2.p we find . h .h P N .pT .2 p
p pDh
' NSUB-ENERGY/SUBCEM project
TUDelft
= -2 26 TECIINOLOCTCommutator
brush surf.a.C41
3/3Tka&in_
-Pole winding A rea (Ow)
The pole winding Area can be found from
A =h .b
P P P with Bo b gives Q -Bo 8 110'kN,ICJwCross-sectional A rea of the pole core (A p)
The cross-sectional Area of the pole core can be deduced in the same
way as thecross-sectional Area of the interpole core
k. ccSt p
B,
k .a.D
A =h .(
").
StP P B
2.p
Now the pole height (hp) can be obtained from
Areal = Area2 2 7I k TC kl Bo Icst. a Da*it hN hp .[
4.p]
hp[4.p.
(Da +2.5)-(B---]+
]+4.p
[_kcu,a Ja hN. Da . 7t B8 .ô IJ.
8. bp p.o.kv.J.
-0
2.3.4 Commutator (figure 2.6):The commutator is an electrical conductor. The commutator together with the brushes take
care of the current supply to the armature windings. like the poles the brushes are divided
around the MEM rotor.
SUB-ENERGY/SUBCEM project
RDM
TUDelft
27
TE IINOL
pole core
Figure 2;7 Magnetic flux conduction of
stator
yoke
andpole core -yoke fiellviadimg /2cb pole shoe intercole
which; = magnetic flux of the stator yoke [Wb]i (kJ can be written as
(1)..=h ..1 ..B
hsi = height of stator yoke
i[mil
11 = stator yoke length (= k.
t
[m]= stator yoke length correction factor [ml,
Bait stator yoke induction (= 1.2 T )
28
SUB-ENERGY/SUBCEM project
RD
)Mgwcazbun
TU Delft_
zr_goiNg OGA valid value for the commutator diameter can be calculated with
k
(b"
+ b.)elk' le
lkk =number of commutator bars
b, = bar breadth (= 5 . 10-3 [mil )
= insulation' breadth (= 1 . 10-3 [m]l
The number of commutator bars (kk) is related to the terminal voltage Cu) by
u U0.2.p
with ut = the 'terminal voltage and i5 [Vi Del eroi,W 4.9931
The 'terminal voltage is limited Ito, A 5V in order to prevent commutator damage. The commutator diameter now become
U0.2. p. (b1 + bi) It
The commutator diameter can never exceed the 'rotor diameter.,
2.3.5 Stator yoke
The calculation of the height of the stator yoke is based oh the magnetic flun conduction of both stator yoke and pole core (as shown in figure 2.7),
b, )
dk
-in
wiadiag
headPo
k4,-Figure 2.,8, Determination of the HEM length
cooling gap slots rotor frame
-
/br
sh holder'
Figure 2.:'91 Determination of the rotor length
ommutator Cooling system
33gwGob-n
Together with z
4)p =bps.lps.Bo Aar = a .1tp. lp.Bo kst
= pole length = le . kit = k15 .
[m]
= iron length =- effective rotor length [In]
= aiirfactor rotor yoke (= 1.2) gives the formula
Bo (T
a)I k
.a)
IctBtit).r
2 (Bsj .). P2 ks2.4 OETERMINAT1ON OF THE MEM LENGTH,:
The MEM length is given by (figure 2.4
1
L1 =la +1t. +2 1
+Z,1 +Z
+ i0 ange ,Lag a rot' k a 2 atrgap arag
With, II = the MEM length
I II inge = flange length
I Jag = length of radial bearing
Inr,Ing = length of axial/radial bearing Irot = rotor length
I k = collector length
lrgnp = length of the airgap
Za = the number of MEM ,armatures.
241 The rotor length (figure 2.9):
The MEM rotor length is given by
cot= =k II +
winding head length 1[111
SUB-ENERGY/SUBCEM
project
J(TUDeilft
29RDIM
n2iw. (V Jai:. TEC. INOLOCY h [m] [m] [m] [m] [m] [m] =S&swGolco
SUB-ENERGY/SUBCEM project
de:4,TUDelft
RDM
aell,67,1,19TemallieAccording to Delleroi 1[W,11,9931 the winding head length(c) can be obtained from the pole
pitch(-0
I
' tp
The effective iron 'length Kle) can also be obtained from the pole pitch and hence the iron length is a function of the rotor diameter (Da)
it .Da
T
2.p
The effective iron length has to be taken about 20 percent longer in order to create a number
cooking gaps. Deleroi ,[W,,I993] gives a correction factor i(c = airfactor rotor yoke) of 1.2 .
Finally
it .Da
cot
= (1 +k).
2.p
2.4.2 The commutator length
The commutator 'length depends on the number of brushes in longitudinal direction. The brush
current density (4) is assumed to be 10 JA/cm]. Knowing the value of the maximum current
intensity (I) the number of brushes in longitudinal direction (ab) can be calculated
ab,
-IB 43' AB
= number of 'brushes in longitudinal direction
= maximum current intensity [A]
AN = brush surface Area = lb . Bb
lb = brush length (= 20.
IV
[m] )1lbiN = brush breadth (= 15. L0-3 11119.),
lk =ab. Ob +tad +1. Ja. p. " ÷ lad +1z
lb,.b8
30
with = brush distance in longitudinal direction l[mi]
= additional safety length of the commutator (= 15 [m],i
le
I0
-)
agT/GOLTIOOsA,
2.4.3. The airgap length
The airgap length (1,,) is assumed to be related to the winding head length (1w) and hence the airgap is related to the pole pitch CO
1
1 = 1
airgaP w 2 P
2.4.4 The bearing length
To obtain a low noise level the use of slide bearings is common in a submarine MEM design
[Ritterhoff, 1983]. At the front side of the MEM a combined axial-radial type of bearing is
used. On the rearside of the MEM we find a radial bearing.
The size of the bearings is related to its load. Deleroi [K,1993] assumed the bearingshaft
diameter- length ratio (Dh.,. to be 1. Db,shaft
1
lb
Dh,shalt = The bearing shaft diameter [m]
= The bearing length.
The bearing shaft is connected to the rotor by a wringing fit. The bearing shaft diameter
(Di,h,I) is related to the torque
PB
M =
7C .00= torque moment [Nm]
= length of the wringing fit (L = 13,han) [m]
= the allowable material stress( = 70 [N/mm2] ) = 0,16
SUB-ENERGY/SUBCEM project
JJ.4,
TUDelft
TEC I INOLOG31
lb = Db,shaft
3
2. PB
The value of the bearing length lb is equivalent to the value of the radial bearing length
The value of the axial-radial bearing Low of the "HOLEC" MEM of the Dutch submarine
Walrus is found to be 10g+0.05 [m]. And this will be used in the model.
So
'rag = lb 1ar
jag = 1r.13g + 0'05
Ir. lag = length of the radial bearing [in]
'ithg = length of the axial-radial bearing [m]
In
water
t
cooler
ventilation
fax
Figure 2.10
Top view of a HEM cooling system
AIR
partition plate
bmot
A.
Figure 2.11
HEM tubular cooler
water
3SCqTGOEDEI
2.4.5. The flange length
The flange length ('fling) is related to the design of the MEM- shaft connection. In this model
the value of the flange length is assumed to be 0.40 [m] (§ 2.11).
According to § 2.4.1 to 2.4.5 the resulting formula for the determination of the MEM length
is:
1 tp
= litange +1.3ag +1,,Lag +Za.((1 + iss). tp)+Za . +za.
'not
,.5 MEM COOLING SYSTEM:
In France and Sweden water-cooled DC-engines have repeatedly been used along with the
successfully proven air-cooled motors. The specific volume for both
types of engines is
approximately the same. The specific weight for the water-cooled motor is approximately
20% higher as compared to the air-cooled motor [Ritterhoff, 1983].
The MEM model in this chapter is based on the (air-cooled) HOLEC MEM and therefore in
this model only the application of an air-cooling system is considered. The MEM cooling system consists of (figure 2.10):
- two cooling fans
- a tubular cooler
the system housing (inclusive. filter)
The capacity of the cooling system of the MEM has to be enough to compensate for the heat
losses.
The heat losses can be calculated with the formula [Beitz, 1990]: 13, = k.AELA
= heat losses
Pi]
AO = logarithmic decrement of the cooler temperatures [K]
= heat transmission coefficient [W/m2.K]
A = cooling surface! with (T1 - t_,) - (T-t1) AO -
-T1 -t, In( ) T2 -t-1SUB-ENERGY/SUBCEM project
TUDelft
32RDM
k a 2Deleroi [K,1993] gives
T, = air inlet temperature cooler (= 343 K )
T, = air outlet temperature cooler (= 308 K )
t, = cooling water inlet temperature (= 296 K )
t, = cooling water outlet temperature (= 301 K )
The heat transmission coefficient (k) is assumed to be 60 [W/m2K1 The cooling surface (A) can be described by (figure 2.11) :
A =
.d.hick. z ,w= the number of pipes in the vertical plane = the number of pipes in the horizontal plane
= cooling pipe diameter [m]
bk = cooler breadth [nt] and hk
=
-StSUB-ENERGY/SUBCEM project
RDM
TU Delft
hk = cooler height [m] = cooler length [m]si = tubular distance cooler in the vertical plane
s2 = tubular distance cooler in the horizontal plane
If n1i
Normally the cooling system is built on top of the MEM. The breadth and the length of the
cooling system are determined by the breath and the length of the MEM. So the height of the cooling system is the only variable.
The cooler breadth (hA)
There is a little difference in cooler breadth and the breadth of the whole MEM cooling
system (= diameter of the MEM (Dm,) ). This difference is mainly caused by the flanges and
pipebends of the cooling water system. Deleroi [K, 1993] gives
bk = Dino, - (2 . 0.4)
The cooler length (I)
The length of the cooler is limited by the cooling fans, the housing and the air filters. A value
of 0,2 [mil for the cooler length (1.01) seems to be reasonable.
33 dl
Rbogolm
L.;The coolerheight (Ii) (figure 2.12)
Deleroi [K, 1993] assumed the values of tubular distance and pipe diameter to be
=- 6. le [m]
s, = Ii. 10-2 [m]
= 8. 1O-3 [in]
Now the cooler height can be calculated with the formula
A.s
s, Pv SI S2hk-
Ibitd
-k. El.lk.bk. rc d
In this formula only the heat losses are unknown. Heat losses are circa 5% of the total power
(PB) are to be expected [Deleroi,K 1993].
2.6 MEM EFFICIENCY
The MEM efficiency can be calculated with the formula
E
Pv= 1
PB
E
Pvin which = the MEM efficiency
ypv = the energy losses
The energy losses can be divided in two parts [Deleroi,W 1993]:
- the No-Load losses - the Load losses
The No-Load losses are independent of the motor load. In case of load additional losses, the
so called Load losses, will appear.
The energy losses can be written as
E Pv = Pload Pno -load
J
TUDelft
34
2.6.1. No-Load losses
The No-load losses consist of
=P
v,Fe +Pv,p +P .f+Pv,f+Pv.i no -load
P110- load = the No-Load losses [W]
Pv.r, = the iron losses [NV]
= the pole shoe losses [W]
Po, - the brush losses [W]
= the excitation losses [W]
Pv., = the bearing friction losses [W]
The iron losses (1)F)
The iron losses can be expressed as a loss-number and iron-volume
Pv,Fe = Za Ve ' Vaj
with
v
= the loss number [W/cm3]= iron volume of the armature [cm]
Deleroi [W,1993] gives v = 0.525.10 5.p.n.(100 +p.n).1312,, in which = 2.1 1 [T] and: = kis.1e.((1-).(13,12-d15 -N.hN.bi,i) 4 Vaj
= kis.le.((7- ). (D.,2 -di2)
-SUB-ENERGY/SUBCEM project
JA.a.TUDelft
Da.7c.hN\ 2 35RDI4
IE3Gweolf2o with = - 2 .hN -2.h4 BA n
B.".
a-
(.)
Baj, the mean armature yoke induction (=LI 1[T] )
The calculation of the height of the rotor yoke(h) As similar to the calculation of the stator
yoke.
The Pole shoe tosses
According to Deleroii r[W, 1993] the pole shoe losses can be determined by 1
.
wighv,p E A the pole face Area
V = the pulse loss number
The pole face Area can be found from
EA =
And the pulse loss number(vo) can be obtained' by
.( 2
4.6
(N.n.60
5 B0.2.p.ipk 1000 0.1.N
with = 0.08 . ke . Bs
ke = the so called "Karterschel" factor 4= frit 6 )
The brush losses (P,,m)
The brush, losses can be found from
Z.
.E A
. F.p.vk IiSUB-ENERGY/SUBCEM project
40.4,TU Delft
36IRDM
= Pv = Z2.p.(a.-C)
) PvB = TECI -)LOCRTAmeDun with and 110
SUB-ENERGY/SUBCEM project
RDM
-0--TUDelft
V = the circumferential velocity of the commutator = dk . it n [m/s]
= the brush friction coefficient (= 0.21 )
= the brush pressure (= 1.5 .104 [N/m2] )
-
2.10E Ab
The excitation losses (P,,)
The excitation losses are given by
Pv,f Za
Uf'If = Za .
Rf = the resistance of the exciting winding,
[n]
I. = the exciting winding current [A]
The resistance of the exciting winding can be found from
Rf P. ow
Acku
with A.Lf - the cross sectional copper diameter of the exciting winding
= 1,./ J (and IF = (Ba . 6) / )
= the contour of the exciting winding
= 2.l = ( I +a)
= the resistance factor of copper (= 1.786 .10 [f2rn] )
The resulting formula for the excitation losses is
4.p. a6.
. par
Jw. tp.(1 +cc) Pv,f = Za 37 = ,. IbEC LUOLOG + 2.b .(
Db,shaft )2
2
(
--= 2 . i cil . 712. n . Db2,shaft . lb . .en . n .Db,sbaft) E
in which ilc = the dynamic viscosity of lubricating oil(= 0.08 [Nsin-iI )
= the bearing clearance (= 0.5 10 [in], )
2.6 The load losses
There can be considered to be two components of Load losses on the MEM - the Joulean heat losses
- the additional losses
The Joulean heat losses can be divided in three components - The armature losses (P)
- the interpole losses (1).h) - the brush losses (1),.b)
PLoad
= PP + Pv,b + P,
v,a vvadd
The armature losses (P)
The armature losses are given by
Pv,a = Za . . E ia2 D -b'shatt 38 = 2. /Ica.(A. .2. TC. 1b . (2.n.IC .
2,
SUB-ENERGY/SUBCEM project
RDMI
RbFiGKDM
TUDelft
TEr ',LOGYThe bearing friction losses (Pr)
The bearing friction losses can be expressed as a friction force(F) and peripheral
veloci-tY(Vshaft)
