Combining Optimum Propeller Design on Roro Ship Re-engine

(1)

2301-9069 (e) 1829-8370 (p)

Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan

(Kapal:

Journal

of Marine Science andTechnology)

H

journalhomepage: http://ejournal.undip.ac.id/index.php/kapal

Combining Optimum Propeller Design on Roro Ship Re-engine H)

Checkfor

I MadeAriana11,Adhi Iswantoro1ÿ, Salsabilla Aulia

Fitri11

of Marine Engineering, Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember, Surabaya 60111, Indonesia

')Corresponding Author: [email protected]

ArticleInfo Abstract

Keywords:

The algorithm;

CFD;

EPM;

optimum propeller;

Passenger shipsserve several areas in Indonesia, one of which is KMP (Kapal Motor Penumpang) Dharma Rucitra 3. In 2020 this ship had an accident and almostsank,then causing themain engine to submerge. With this problem,it is necessary to repower the engine provided by the company by replacing the old engine witha newengine. Thenewengine, namelyYanmar 6N21A SV, withapower of 1200HP at 850RPM. Initially, the ship's speed was 12 knots with the data of Makita GNLH 630M enginewithapower of 1300HPat 375RPMwithaB4-50 propeller.To achieve the desired speed, it is necessary to havean optimal propeller to improve engine performance. In thisresearch,an algorithm has been specially developed to find the optimum propeller designof B-series propellers for KMP Dharma Rucitra 3 by defining the overall parameters ofapropeller-likediameter,pitch-ratio, blade area ratio and the number of blades. The optimum propeller design is performed as a multiobjective function to constraints imposed by propellerparameters.Thecomputerprogram hasbeendeveloped toselect the optimum propeller by considering the boundary conditionof the system, hull-propeller interactions, and engine-propeller matching (EPM). This research also carried out open water and self¬

propulsionsimulationsusingcomputationalfluiddynamics (CFD). Then itcanbe concluded that the developmentofan algorithm to optimize the selection of propellers on KMP Dharma Rucitra 3 obtained propellers withB4-49.6typewithadiameterof 1,995m sothat itcanreachaspeedof 14,2 knots at 85%maximum continuous ratingof engine power.

Articlehistory:

Received:12/03/2023

Lastrevised:18/05/2023

Accepted:20/05/2023

Available online:20/05/2023 Published:20/05/2023

DOI:

https://doi.org/!0.14710/kapal.

v20i2.52979

1. Introduction

Theship has the abilitytoreach awider area,includingremoteareas. Inaddition, thecosts incurredwhen usingsea transportation servicesare more efficient because theycan transport goods or people in large quantities at lower prices.

Ships arecategorized intoseveraltypes,oneof whichisa ro-ropassengership.Oneof the ro-ropassenger ships servingthe Bali-Lombok ferry route and viceversa is the KMP Dharma Rucitra 3. Ro-ro passenger ship owned byPT.Dharma Lautan Utamais equipped withatwin-screwpropulsionsystem.This shipispowered by a dieselenginemanufactured by Makita GNLH630M withapowerof1300HPat 375RPM.On

June

^{12, 2020,}^at^Padangbai^Port,Karangasem, Bali, thisship hadan accident andalmostsank.Thiscauses diesel engines to be submerged in seawater foralong time due to many administrative processes. Thus, causing corrosionon themain engine. Therefore, theMakitaGNLH630M enginewill be replacedwithan engine that isalready in thecompany'swarehouse withthe Yanmar6N21A SV manufacturer,which has apowerof1200HP at 850RPM.The reason for usingaYanmar 6N21A SV because the engine is already in the company's warehouse,so the company does not need tobuy a newengine.

Toachieve thedesired speed, it is necessary to havean optimal propellerto improve engineperformance. Criticaldesign analysis in aship propulsion system is the optimal matchingof the propeller to the hull interaction. Choosing the right propulsion system to match the hull and engine is a very important decision. The engine propeller matching process considered the interaction between thehullof the ship and the diesel engine. The engine and gear ratio matches when the enginetorqueand propellertorquearebalanced,which means theenginewillnotoverload[1].Torealize thedesired speed service, designingthe optimal propellerto improve thehighengineperformanceand reducecostsfrom fuel oilconsumption and vibration-inducedstresseson the ship[2],

Thereare three parameters that limit the propeller design, such as propellerdiameter,highestpropeller efficiency and cavitation phenomenon, cavitation hastobeconsidered andcontrolled in thedesignprocessby the propellerdesigner, and it has certainly changed how the propeller design isinvolved.The primemover is one of the major steps in shipbuilding projectsbecauseofisusuallyoperateduntil the lifetimeof the ship[3],To optimizetheprimemoversystem, thefollowing parameters, typeof propulsion, fuel oil consumption, payload, maneuverability, principal maindimension, environment,

(2)

etc.,mustbe considered [4],Reducingfuelconsumption,low emission control, noise and vibrationduetopropeller matching is required[5],

The optimumpropellerdesignproblem can be handled using thepropellerseries diagramsorregressionpolynomials [6], Thispaper addresses improving andevaluating the performance based on the algorithm. The algorithmisappliedtofind optimalsolutions by defining the overall parametersofapropeller-likediameter,pitch-ratio,bladearea ratio and the number of blades[7], This researchhas input design parameters suchasspeed service,wakefraction,thrustdeduction fraction,total resistance, number of blades,maximum diameter, engine power,servicemargin, engine margin,and shafting efficiency.

Input design parametersfor considering hull-propeller interaction and engine-propeller matching, and iterate the variables in therange to get optimumpropeller efficiency.

Basedonthebackgroundthat hasbeen mentioned,the authors will analyze theimpactof replacing the MakitaGNLH 630M engine with theYanmar 6N21A. This research it is aimed to get the optimum propeller usingan algorithm with Microsoft Excel so that the shipcanachieve the highest performance.

2. Methods

2.1 Research Method

The methodsare the main difficulty in mostoptimization problems. It defines in formulating the objective all the constraints.Anyconstrained optimizationproblem couldbehandled by theoptimization designpropellerprocess shownin Figure2.Optimum designpropellerprocess impressionby hullinteraction and enginepropeller matching. The correlation between the engine and propeller is shown in the service condition shown in Figure 1. The services condition refers to the meanserviceconditionsthat the ship willencounterin itsoperational life.Good practiceinvolvessomehull fouling (e.g., two years),sea state 2 or3,deepwater and design displacement. The operating envelope is used to plot the propellerload at design condition andtrial condition with the Engine Margin (EM) and service margin (SM) boundary.

propeller loadat designconditions

i

operating envelope

propellerload at trialconditions 100 MCR

90 EM CSR

80

70 SM power during

seatrial 60

50 40 30 20

10

n.

0

ne

0 10 20 30 40 50 60 70 80 90 100 ^n*

M

Figure 1. Correlation between Engine and Propeller at Service Condition[8]

Thefuel coefficient identifies the fuel flowandlogspeed.This givesthe overall ship performance, including theengine, propellerand hull. Thepowercoefficient identifies the shaftpower andlogsspeed, and this givesthe overall efficiencyof the propeller and hull, excluding the engine. The specific fuel consumption (SFC), propeller, and hull coefficients isolated the individual componentsgivingthe efficiencyof each independently.

(3)

ρ

𝑉_𝑎= 𝑉_𝑠(1 − 𝑤)

O

^Fuel

o

^Power ^RPM

*

^Speed

/ *

\PropellerCoefficient

7

SFOC Coefficient Hull Coefficient

7

PowerCoefficient

Fuel Coefficient

Figure2.Coefficient parameters for the ship's performance (Fathom world)

Figure 3below showsthe stepsofcarryingout this researchfromstart tofinish indetermining the optimumpropeller with a newengine,but thespeedofthe shipcanbe achieved.Theinitialstage istocollectdatafromtheoldenginewith the new engine,as well as data from the KMP Dharma Rucitra 3 ship. The shape and characteristics of the ship have not changed, but withthe presenceof a newenginethat has differentcharacteristicsfrom the oldengine, it isnecessarytomakeadjustments to the ship's propulsion system,with the hope that the speedof the shipcan be achieved. In this^research,thefocus ison the propeller selection process(including the efficiency,diameter and cavitation of the propeller)and also the calculationof enginepropeller matching, which can beoptimized.

Start CalculateKT(o), KQ(o).

AKQ(o)

I

/Input data: Vs, Rt,

fw,t,N, Dmax,P, h,p, v,z(3-7)

/

No Yes

Calculate:

KTopen(o)=^KT(o)

KQopen=KQ(o)

Calculate:

KTopen(o)=^KT(o)⁺^AKT(o)

KQopen=KQ(o)+AKQ(o) Rn > 2x10A6

T

Calculate Va, Jmin, T,P/D

1

Collect data:Z(i), D(e), Ae/Ao(u), PD(o),

I

KTopen(o), KQopen(o),Efipropfo) IterationZ(i), J(e), Ae/Ao(u)

No OptimumJ(e), Ae/Ao(u), Z(i)?

CalculateD(e),Tc(e),PD max(e),KTLoad(e)

T

Yes

Yes Calculate: No

Ct<e)=2,14/(Z(i)*D(e)*AeAo(u))

Calculate:

Cr(e)

-

2,185/(Z(i)*D(e)*AeAo(u)) Choisefromthe saving data: Z, D, Ae/Ao, PD,KTopen, KQopen for the highest

Eflprop(o) Z(i)=³

I I

Finish CalculateRn(e)

I

IterationPD(o)

Figure3. Methodology

Integratinga propeller, ship hullandtheengineiscalled enginepropeller matching. The total resistanceof the ship withacertain speedmustbeknown.It means the torque and thrust of the propeller selection overcome the resistance and engine that match the propeller. The basic data of propeller design in order to introducethe relationship between the propeller diameter (D), velocity (Vs), advance velocity (Va), wake friction parameters (w), the rate of revolution (n), the densityof the water ( ), of which important coefficientsare discussed below[9,10],

The advance velocity.

(1) Where;

Va :advancevelocity,

m/s

Vs ^:service velocity,

m/s

w : wake friction The thrust calculation.

(4)

𝑇 = 𝐾𝑇. 𝜌. 𝑛². 𝐷⁴ 𝑇 = 𝑅𝑡

(1 − 𝑡)

ρ

𝐾_𝑇= 𝑅_𝑡

(𝜌. 𝑛². 𝐷⁴. (1 − 𝑡))

ρ

𝐾𝑇= [ 𝑅_𝑡

(𝑉_𝑎². 𝜌. 𝐷²(1 − 𝑡))] . 𝐽² 𝐾_𝑇= [ 𝑅_𝑡. 𝑛²

(𝑉𝑎4. 𝜌. (1 − 𝑡))] . 𝐽⁴

ρ

𝐽 = 𝑉_𝑎 (𝑛. 𝐷)

𝐾_𝑄= 𝑄 𝜌. 𝑛². 𝐷⁵

ρ

ƞ

(2) (3) Where;

T :thrust,1<N I<T : thrust coefficient

:water density,kg/m3

n :rotationof propeller,rotation per second D :diameterof propeller,m

Rt ^:resistance,kN t :thrust deduction Thethrust coefficient.

(4)

Where;

I<T : thrust coefficient :water density,kg/m3

n :rotationof propeller, rotation per second D :diameterof propeller,m

Rt ^:resistance,kN t : thrustdeduction

The propeller load characteristic.

(5)

(6) Where;

I<T : thrust coefficient :waterdensity,kg/m3

Rt :resistance,kN t : thrustdeduction

Va :advance velocity,

m/s J

^:^Advancedcoefficient Advancecoefficient.

(7)

Where;

Va :advancevelocity,

m/s

The propeller torque.

(8)

Where;

KQ :torquecoefficient :waterdensity,kg/m3

n :rotationof propeller,rotation per second D :diameterof propeller,m

Q :torque,Nm

Basedonthe propeller diagramsispossibletocalculatethepropellersize,the shaftpower andthe efficiency, whichare amongstJ,KT,andKQ. curves,off design conditions which the operating aspect of the propellercan be analyzed from open water diagrams[11,12], Thisstep is usedto progressfurther in solving some off-design propeller that affects the operational envelope [13], Propeller characteristicparameters KT, KQ values depend on thenumberof blades (Z) from2 to 7,arearatio (Ae/Ao)from0,2to1,05,pitch diameter ratio (P/D)from0,47to1,5and advancecoefficient (J).

(5)

𝐾_𝑇= ∑ 𝑐_{𝑠,𝑡,𝑢,𝑣}^𝑇

𝑠,𝑡,𝑢,𝑣

(𝐽)^𝑆 (𝑃/𝐷)^𝑡(𝐴_𝐸/𝐴₀)^𝑢(𝑍)^𝑣 𝐾_𝑄= ∑ 𝑐_{𝑠,𝑡,𝑢,𝑣}^𝑄

𝑠,𝑡,𝑢,𝑣

(𝐽)^𝑆 (𝑃/𝐷)^𝑡(𝐴_𝐸/𝐴₀)^𝑢(𝑍)^𝑣

𝜂 =𝐾𝑡

𝐾_𝑞 𝐽 2𝜋

𝜂



𝐽_𝑚𝑖𝑛= 𝑉_𝑎/(𝑛 𝐷_𝑚𝑎𝑥)

𝜎0.7𝑅=188.2 + 19.62 ℎ 𝑉_𝐴²+ 4.83 𝑛²𝐷² 𝑛²𝐷²=𝑉_𝑎²

𝐽²

𝜏𝑐−𝑙𝑖𝑚𝑖𝑡= 𝑓(𝜎0.7𝑅) = 𝑓(𝐽)

𝜏_𝑐= 𝑇 1 2𝜌𝑉_𝑅²𝐴_𝑝

The polynomialequationsfor theB-Seriespropellerwill beusedtoplot theopenwatercharacteristics, numberof blade ranges, bladearea ratio and the ratio of pitch diameter[ 14],The polynomial equation explains thecorrelation between thrust and torquecoefficient intermsof the number ofblades,blade arearatio, advancecoefficientandtheratioof pitch diameter.

Thepolynomialequationwithmultipleregressionis:

(9)

(10)

(11) Where;

I<T ^:^thrustcoefficient KQ :torquecoefficient

J

^:^Advancedcoefficient : efficiency,%

Z : number of blades

P/D:

^pitchdiameter ratio

Ae/Ao

^:^{area ratio}

The parameterof characteristics of open water tests suchasI<T,KQ, 0,J,and

P/D

can be seen in equations (1) and (12).

The advance ratio (J),wake friction (w) and rotationof the propellerare determinedasaship speedfunction.The boundary conditionof the stern shipspaceisthe maximumdiameteraffected by the advanceratio

J.

(12) Where;

J

^:minimal advance coefficient

n :rotationof propeller,rotation per second

Va ^:advance velocity,

m/s

Dmax:maximal diameter of propeller,m

Cavitationon the back of propeller blades was constrained according to the Burril diagram[15],Cavitationisdefinedas the processof thevaporphaseof a liquid when itissubjectedto reducedpressure at constant ambienttemperature.It occurs when large suction pressures build up near the leading edge of the blade resulting in the back of the blade being covered with a sheet of bubbles [16], The thrust loading coefficientmustbe lessthanthemaximumthrust loading coefficientand maximum cavitationleveladopted byTable 1. The boundaryconditionofcavitationcanbe calculated byusing theformula (13).

Table1.ManufacturingAccuracyof Propellers[13]

Class ManufacturingAccuracy MeanPitchfor Propeller S Very high accuracy

1 Highaccuracy 11 Medium accuracy 111 Widetolerance

±0.50%

±0.75%

±1.00%

±3.00%

(13)

(14) Thecriticalthrustcoefficientcanbe calculated byusingthe formula (16).

(15) (16)

Where;

Ap : theprojectedarea,m Ad :the developedarea,m Va ^:advance velocity,

m/s

n :rotationof propeller,rps

(6)

𝐴_𝑝=(1.067 − 0.229𝑃 𝐷) 𝐴_𝑑

𝐽_𝑚𝑖𝑛= 𝑉𝑎(𝑛 𝐷_𝑚𝑎𝑥) 𝑃

𝐷_𝑚𝑎𝑥= 𝑓(𝐽)

𝑃𝑟𝑜𝑝𝑒𝑙𝑙𝑒𝑟 𝑆𝑝𝑒𝑒𝑑 = 𝑀𝑎𝑥. 𝑆𝑝𝑒𝑒𝑑 𝑥 (1 − 𝐸𝑀)^𝑚¹ 𝑚 ≃ 3

    



– D : propeller^diameter,m

(17)

Therearetwoboundaryconditionsof thiscalculation, minimum advance number and ratioof P/Dmax, shown inFigure 4.

PROPELLERS UAGENINGEN B-SERIES

FOR 4 BLROES RE/flO 0.S0 TO 1.40 :.900 P/0-

<£

•>

UJ

fe!

§

-

¹

J

o

82

n

^,

—

^C

$

^I

.

1.00 I

0.00

R0VRNCE COEFFIJI

Figure 4. Boundary condition to choose datapoints

1.20 ‘1.40^*

Jhnin

0.20

(18) (19)

(20) In thisresearch, thedevelopmentof the algorithmstarts withselectingenginesandgearboxes that are applicableto the propulsion system. Estimated powercan be calculated by:

Power =(Rt.Vs)

/

⁽ ^HORS ^gb) ⁽²¹⁾

The formula added by SM & EM where 0 depends on the type of ship. After selecting the engine, input design parameters suchasVs.,w, t, Rt,numberofblades, diameter maximum, engine power & speed, SM, EM, andshafting efficiency.

Change all equations as a function of design parameters and variables Z, Ae/Ao, P/D,

J.

For considering hull propeller interactionand engine-propellermatching,iteratethe variables in the rangeto getoptimum propeller efficiency.

2.2 Toolsusedin research

Thetools used during the propeller optimization areasolver using Microsoft Excelsoftware and computational fluid dynamics(CFD)usingNumecasoftware.

1. Solver

Thealgorithmthathas been developedtoselect the optimal propeller uses the solver inadds-inonMicrosoft Excel. This is because itsimplifies the calculationprocessinaccordancewith the methodology. Solver makes thesystem consider the desired result without ignoring thevariables within predeterminedlimits.

2. Computational Fluid Dynamics (CFD)

Becausetheinputdatafor the solverusesassumed values for the wake and thrustdeduction, it is necessary tocarryout asimulation in the form ofaself-propulsion test with CFD. The simulation usesadisk actuatorso that input is needed in the form ofI<T,KQ,and

J

^values^from^{the open}^watersimulation.

3 Results and Discussion 3.1 ShipResistance

Initially, the ship's resistance at each speed was calculated using the Holtrop method, maxsurf Holtrop, and CFD simulation methods.However, the datatakenfor furtherprocessing isthemaxsurf Holtropresistance,whose valuehasbeen matchedwhether it is close to the Holtrop method.Furthermore,the resistance valuefrom CFD simulation is validated by Holtropmaxsurf.So,it is ensuredthat for each resistance, it mustbeclose,with a difference of ±^5%.The simulated speed using CFD isfrom 11 to 15knots.Figure5isacomparisonof the resistance value of maxsurf simulation (Holtrop method) and CFDsimulation.

(7)

–

ρ

–



160

140

120

¥_jy

IOO

-

Maxsurf (Holtrop)

-

^CFD

80

60

40

10 11 12 13 14 15 16

Vs

Figure5.Ship resistancevaluefrom Holtropmethod,maxsurf software, and CFD simulation at various speed 3.2 Propeller Optimization

BecauseKMP Dharma Rucitra 3 is being repowered with the new engine, Yanmar 6N21ASV,withapowerof 1200 HP at 850 RPM, it is necessary to change the propeller as well toachieve the highest performance. The selection of a new propeller is made by optimizing usinganalgorithm. Firstly, anoptimization algorithm that is capableof developing the enginepropeller matchingprocess consideringhull propellerinteraction andengine-propeller matching.Analgorithmstep isbased on algorithmic development.Thereare many waysto fill in thesesteps, dependingonthe problem in thecase. The algorithm contains the basic part thatwas given in methodology Figure 3. This characteristic can be found in the selection andreplacementpartof the algorithm. Themain steps,asshown inFigure 3,arenow explained in moredetail.

Table 2.InputData Value

InputData Unit

53,85295 kN Shipresistance,Rt

Ship speed, Vs Block coefficient, Cb Enginepower,P

Wake deduction factor, W Thrust deduction factor,T Max. propellerdiameter, Dmax

Height,H Rotation,N Seawater density, Kinematic viscosityat 27C Allowable Stress Material (Manganese Bronze)

Numberof blades, Z

knot 13,75

0,628

882,5985 kW 0,02828 0,14707

2,65 m

1,809

5,6413591 rps

1025 kg/m3

0,00000087

m/s2

39

Mn/m2

m

4-7

The optimization process istheobjectivefunctionof selecting the propeller thathas themostoptimalperformanceand design variables as propulsion parameters. Component design characteristics refer to the propeller and engine data specification that will beinput in the first stepof the process.All of thecomputations wereexecuted by the solveron Microsoft Excel. Theaimapproach shows anoverviewof each calculating model.Thefirststepof algorithmic development isto input thehull information, ship, engine, and propeller data suchas speedVs.,resistanceRt,wake friction w, maximum propeller diameterDmax,ratio gearbox Rgb,etc.Table2shows the input dataof the algorithm process. With the above-given data,a matching pitchis achieved,with another case representinga rangeof pitch ratios. The information defined in the open water diagram is achieved,which is used to construe the open water efficiency curve, torque coefficient, thrust coefficient,totalresistance, andadvance ratio.

The variation in coefficient is a sign that various case of the ship affects the performance of the hull propeller interaction and engine-propeller matching. Constraint the iteration Z(i)from 3 to 7 with interval1,iteration

Ae/Ao

^(u):^from

Jmin

to 1,05 with interval 0,01and iterationJ(e):from

Jmin

^{to 1,5}with interval0,01.Thrust and torquecoefficient ofthe Wageningen B-seriesaredelivered as polynomials inthe advance ratioJ, thepitch ratioP/D, the blade arearatioAe/Ao,and the numberof bladesZ.Then,calculate the propeller performance suchas D(e), Tc(e), P/Dmax(e) and Knoad(e). Reynolds numberRn^iscalculated in the polynomials,thecorrelation shown inequation(9) and equation (10).

Oneof theexcesses of the applied optimization algorithm is obtaining various design data,even of onlyone.This is necessaryfor making the final decision. For example, the pitch of the propeller change based on the value of

J

KT, KQ, and o,

(8)

whichsign the effect of pitch ratio on the hydrodynamiccurve of the propeller design.Table3shows the result of the optimization algorithmfor each propellerblade.

Table 3.Outputdata

Z=4 Z=5 Z=6 Z=7

Maximal diameter, Dmax DiamaterPropeller, D FacePitchRatio,

P/D

Advance Coefficient,

J

BladeRatio,

Ae/Ao

Propeller Efficiency

Jmin

(tmin/D)0.7R Tmax KT load

2,65 2,65 2,65 2,65

1,9831622 0,8198936 0,6138538 0,4937391 62,307%

0,459386 0,007556 0,0156 0,125133 0,125125 0,01963 5,641359 5,641359

1,88757248 1,8726362 1,8112626 0,8998101 0,9094749 0,9819309 0,64494039 0,6500845 0,6721122 0,58663852 0,6296112 0,6527621

59,751%

0,459386 0,007853 0,0141 0,152472 0,152155 0,026152 5,641359 5,641359

57,346%

0,459386 0,007906 0,0126 0,157395 0,157077 0,028354 5,641359 5,641359

55,420%

0,459386 0,008085 0,0111 0,179837 0,186909 0,036095 5,641359 5,641359 KT

KQ.

Rotationnoutput Rotationn input Rotationndeviation Thrust,T

Torsion, Q.

Torsion, Qb

DeliveryHorse Power, DHP

BrakeHorse Power,BHPscr ^734,2585

0 0 0 0

63,13483 19,64258 19,70169 697,9862

63,00741 20,44142 20,50293 726,3724 764,1199

63,01117 21,29989 21,36398 756,8774 796,2102

65,62176 22,95346 23,02252 815,6359 858,0222

Fromthefour propellers in Table3,the propeller that has an85%maximumcontinuous ratingofenginepowerfor the Yanmar 6N21A SV engine is selected, namely the B4 propeller with

Ae/Ao

^0,493.From the typeof propellerobtained,then drawthe newopen-waterpropellerdiagram. This openwater diagram is used tofindpower and rotationfor each speed using B4-49.3 propellers with new engines. The following Figure 6 isanopen water propeller diagramfor thenew B4-49.3.

IjO 0.9 0.8 0.7 0.6

-

^KT

-

^10KQ

OA

-ⁿ⁰

04 04 0,1 Ofl

0 0,1 04 04 04 04 04 0,7 04 0,9 1

J

Figure6. B4-49.3^propelleropenwater diagram

Foreach speed,powerand rotationare calculatedbasedontheold B4-49.3 openwater propeller diagram. By finding the intersectionof the rough hull values for each speed, the KTOpen,KTLoad,andKQ.valuescan be calculated where the valueof KTOpenandKTLoad must bezero.^Thisvaluecanbe searched using theMicrosoft Excelfeatureusing goalseek in what-if analysis.Afterthat,thevalueof rotation and powercan becalculated.The rotations and powerare tabulated, making it easier to plotonthe engine envelope graph.InFigure 7, itcan beseen inthecurve namedB4-49.3thatat85%brake horsepower (BHP), itcan reacha speedof13,75knots witharotationof797,6rpm. So that it can be said that the engine propeller matchingmeans that the operating point of the ship's engine rotation is such that it matches the propeller loads B4-49.3.

(9)



/

800

700

-

I

_•_{B 4-49 3} _-_B4-493

0 5

RPM Speed

Figure7.B4-49.3 Propeller curve and speed-power curve 3.3 Self-propulsion Test

The valueof the wakeand thrust deduction factor asinput data for the optimization algorithm is assumed,so it is necessary to lookfor values derived from the self-propulsiontest.By testing thehull and propeller simultaneously in the samedomain,the fluidinteraction between thehulland propeller will be known. Inthis simulation, the input used is the ship'sspeedand I<T,KQ,and

J

^from^outputvalues in theopen watertest.Sofirstly, simulatingopen water testastheinputof self-propulsiontest.An open water test simulatesapropeller selected with fixed propeller rotationon5,6414rps, various advancespeeds(Va), andvariousadvance coefficients (J)usingtheCFDmethod.InputtedvaluesofVaare4,4751m/s,5,5939 m/s,^6,7127m/s,^7,8315m/s,and8,9503m/s,while the inputted valueof

J

^from^0,4^to^0,8^with^0,1^interval.Before running this simulation,it is necessary to domeshing firsttodefine the propeller sothatit is divided intoseveralnodes andelements.

Meshing in this simulation hasatotalof627,388cells.The meshing and test resultsare shown in Figure 8 asfollows.

;5

•s- -J

:|§: gL.

‘fefl

^-

e

BIOllI p=:=-

Figure 8. Open water test meshing and propeller geometry

1,0 0,9 0,8 0,7

2

_0,5^0-6

n

fe¬

0,4 ^ll)KQ 0,3 KT_

0,2 0,1 0,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9

J

-

^KT1

-

^10KQ1 ^-nOl

-

^KT2

-

^10KQ2

-

ⁿ⁰²

Figure 9.Openwater diagramvalidation

Withthissimulation, output datasuch asthrust(T)and torque(Q).Thisvalue can be seen on themonitorstartmenu in the Fine Marine software.The thrust value is in the forcessection,while the torque value is in the moment section.

Validationwill be acceptedifthedifferenceof each coefficient is 5%. From the calculation, the validation of the data can be accepted. Figure 9 is thepolynomialandsimulation open water diagram.Figure 9showsacomparison ofthevalues ofKT, KQ.andefficiency between polynomial calculationsandsimulations in open water conditions.Fromthe figure,itcanbeseen thatifthevalueof

J

is between 0.4 to0.65,then the valueof the simulation efficiency is greater than thecalculation.While

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𝑉𝑎= 𝑛 𝑥 𝐽 𝑥 𝐷 𝑉𝑎= 5,59 𝑥0,654 𝑥1,983

𝑉_𝑎= 7,2573 𝑤 = 1 −𝑉𝑎

𝑉𝑠

𝑤 = 1 −7,2573 7,588

for10KQ.&KT, thesimulation valueissmaller than the calculation.Forvalues between 0.65and 0.8,both scenarios produce almost thesameresults.

AfterI<T,KQ,and

J

is obtained,then calculating the ship'sspeedisaninputof the self-propulsion test. The ship'sspeed isobtained by calculating theengine propeller matching between the newengine and propeller B4-49.3usingclean hull resistance. In this simulation, the propeller used is in the form ofadisk actuatorso that in modeling, the data will be input from theopen watertest.Aswith theopen water simulation,beforerunningthe self-propulsionsimulation, it is necessary to domeshing firsttodefinethepropeller sothatit is divided intoseveralnodes andelements. Meshing in this simulation hasatotalof2,264,592cells.Thetestresultsare shown in Figure 10 asfollows.

3.75- f

3.5-

'~r 3.25-

—

^T ^3-

C _2.75-

\

7 25

Figure10. Self-propulsiontestsimulation

From this simulation, thevaluesof n, I<T,KQ, and

J

are obtainedas the output. This value can be seen on the monitor start menu in the Fine Marinesoftware.The outputvalue shown in Figure 11 isthat n is 5,59 rps,KTis 0,112819,KQis 0,019205,and

J

is 0,654638.

n:5S93i

/

J:0 654638 KT:0.112819 KQ:0.019205

TimeTs)

Figure11. Theoutputvalueof the self-propulsiontest

From the output value, advance velocity would be obtained and then would be used to calculate wake with the following formula: [17-19]

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(11)

𝑤 = 0,04357

𝑡 =𝑇 − 𝑅_𝑡 𝑇

𝑡 =54080,58– 52314,7 54080,58 𝑡 = 0,032653

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Thrustfrom the self-propulsion test would be used to calculate thrust deduction factor (t) using the followingformula:

[17-19]

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Initially, the wakeandthrustdeductionvalues were onlyassumptions,with valuesof0,02828and 0,1471,respectively.

Thisvalue is differentfrom the simulationresults.Therefore, optimizationof the selection ofnew propellers is carried out usingthe new wake and thrustdeductionfactor values asinputs.Thenthe propeller results are obtained with type B4-49.6 because,in the beginning,it usedtheassumptiononthe valueof wake and thrust. The followingisTable4,whichcontains datafrom propellers with simulated wandfvalues,namelyB4-49.6,meanwhile propeller data withassumedwandtvalues, namely B4-49.3.

Table 4. Propeller data of B4-49.3 and B4-49.6 Propeller B4-49.3 Propeller B4-49.6 Data

Diameter (m) 1,98316 0,81989 0,49372

1,995 0,8272 0,4968

Ae/Ao P/D

Fromthe typeof propellerobtained,then draw the newpropeller open water diagram. Figure12 istheopen water diagram.

1.0 0.9 0.8 0,7 0.8

So,

^V ^0,4

- —

^KT^10KQ

-

^nO

0,3 0,2 0,1 0.0

0 0,1 0,2 0,3 0,4 0.5 0,6 0,7 0,8 0,9 1

J

Figure 12. B4-49.6 propeller open water diagram

Then,fromthe diagram,wecanlookforthe rotation andpowerthatcanbe achieved byaship’s speedinthesame way as on the previous propeller. The rotations and power are tabulated, making it easy to plot onanengineenvelope graph.

Figure 13 showsagraphofthe propellercurveand speed-powercurve.

1000

800

600 600

s B4-493 i -B4-493

B4-496wt -B4-496wt

200

0

RPM Speed

Figure13. Propellercurveand speed-power curve of B4-49.6

Figure 13 shows thecurve named B4-49.6 at^85%BHP can reachaspeedof14,2knots.Sothat itcan be said that the B4- 49.6 propeller matches theYanmarengine, meaningthat theoperating point of the ship'sengine rotation issuchthat it matches the propellerload.Then thecurve shows that the power value is lower than the power value on the curve named B4-49.3 because^it has a different thrustdeduction(t) value. The fvalue used on the propeller B4-49.6isthe resultofa

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“ ”

“

”

simulationis 0,032,while the propeller B4-49.3 uses the assumed fvalueof0,147.The t value hasdecreased,sothepower value has also decreased. The thrust deduction value decreases because the position of the propeller and the hull is far away, whichcausestheeddyresistancetodecrease.Eddyresistance is caused bythechangingpressure around the shipdueto changesin velocityinducedby theeddiesof thestream separatingfrom the hull surface.

Then from the new B4-49.6 propeller, a self-propulsion simulation was carried out to find the wake and thrust deductionvaluesfor the propeller. The wakeand thrustdeductionvalues are0,035and0,071,respectively.This valuehas differences from the value in the first simulation with the B4-49.3 propeller because of the difference in input for the type of propeller and the speed that the ship can achieve due to the new propeller, for the self-propulsion simulation results of B4- 49.6 propeller can be seen inFigure14.

*

'

0B

04 04

A

Figure14. Self-propulsiontestsimulation

I

4 Conclusion

Basedonthe analysisof calculationsand simulations inthis research, itcanbe concluded that the development of an algorithm to optimize the selectionof propellerson KMP Dharma Rucitra 3 obtained propellers with B4 type with

Ae/Ao

ratio is 0,496,propeller diameter1,995 mand

P/D

ratio is 0,8272. Optimizationof the propeller selectionwascarried out using thesimulated wake deduction value is0,0435and thrust deductionvalue is0,0326.The propellercan reachaship's speedofup to 14,2knotsat 85%of theengine'sbrakehorsepower.

Acknowledgments

Theauthor would liketothank the staff of the Marine Power and Propulsion LaboratoryandPT DharmaLautanUtama fortheirsupport so thatthe authorcancompletethe research.

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