RESULT AND DISCUSS

PROPULSION ANALYSIS OF FAST ATTACK CRAFT MISSILE (KCR 60) USING NUMERICAL COMPARISON AND MODEL TEST METHODS

3. RESULT AND DISCUSS

3.1 Propulsion Analysis of KCR 60 M)

One of the causes of the failure to achieve the desired service speed is a result of mistakes in planning the ship's propulsion system (Setyo, 2015).

Propulsion analysis on KCR 60 M is used to determine the size of the shaft power (PS) of the ship and propeller technical specifications to meet the desired service speed (VS). Calculation of powering using numerical methods (DESPPC and PREDFDS programs) and model test results.

3.2 Selection of Propulsion Calculation Methods KCR 60 M.

To obtain the appropriate calculation method for analyzing KCR 60 propulsion, the authors compared the results of the calculation of propulsion at draft 2.4 m. Propulsion analysis is carried out at

2.4 m due to the retesting of ship speed and a half load of KCR at draft 2,4 m.

Table 1. Results of power calculations from the DESPPC, PREDFDS, TRIBON, and model test at

draft 2.4 m

Vs (Knots)

DESPPC PREDFDS (PS) TRIBON

(PS)

MODEL TEST

(PS)

PS(kW) BAILEY (kW)

HOLTROP

(kW) (kW) (kW)

20 2739 2443,07 2869,52 2083

20,5 2979 2656,06 3329,66 2281

21 3226 2877,57 3818,28 2486

21,5 3481 3102,76 4334,53 2697

22 3742 3300,65 4861,86 2914

22,5 4010 3505,17 5402,26 3137

23 4284 3716,47 5935,75 3365

23,5 4565 3915,11 6451,67 3599

24 4850 4115,2 6944,23 3838

24,5 5142 4320,4 7409,37 4083

25 5424 4522,58 7845,76 4332 4662

25,5 5678 4721,74 8253,18 4529 4888

26 5916 4924,73 8633,05 4715 5119

26,5 6145 5136,96 8994,37 4893 5352

27 6364 5343,11 9326,48 5063 5585

27,5 6572 5556,21 9665,72 5226 5820

28 6777 5772,25 10039,54 5396 6067

28,5 6978 5988,76 10399,46 5605 6316

29 7197 6207,65 10744,5 5815 6550

29,5 7460 6428,78 11080,57 6027 6773

30 7757 6650,43 11410,13 6243 6982

Fig.3. Graph of power calculation results from the DESPPC, PREDFDS, TRIBON program and model

tests at draft 2.4 m.

From the KCR 60 M technical data it is known that the installed engine power (PB) is 5760 kW (PS

= 5702.4 kW). By using Figure 4.2, at shaft power of 5702.4 kW, the maximum speed will be obtained as follows:

a. DESPPC : 25,59 knot

b. PREDFDS (Balley) : 27,84 knot c. PREDFDS (Holtrop) : 22,78 knot

d. TRIBON : 28,73 knot

e. Uji model : 27,25 knot

3.3. Use of Admiralty Coefficient (AC) in KCR 60 M Propulsion Analysis

From table 1. is known that by using 5 calculation methods, 5 prediction results are different.

To determine which method to use, an engineering adjustment action needs to be done. In the world of naval architect, the admiralty coefficient is often used to predict the amount of engine power using a comparison ship and the FPB 57 vessel as a comparison vessel was carried out to calculate the magnitude of the admiralty coefficient of the ship designed (KCR 60 M). FPB 57 is a ship made by PT X through its proven technology transfer process with the German State, so that it is worthy of being used as a reference in analyzing KCR 60 M propulsion.

The ship data can be seen in the table below.

Table 2. Comparison of FPB 57 and KCR 60

DATA FPB 57 KCR 60

PRINCIPAL M PARTICULARS Length Overall (LOA)

58.10 m 59.80 m Length Water

Line (LWL)

54.40 m 54.91 m Breadth

Moulded (B)

7.62 m 8.10 m Depth

Moulded (B)

4.75 m 4.85 m Draught Full

Load (d)

2.95 m 2.60 m Displacement

(full load)

445.00 tons

460.00 tons Displacement

(half load)

378.00 tons

382.00 tons Speed/speed

actual sea trial

29/32.4 knots

28 knots/- Range at

cruising speed

3500 nm at 20 knots

2400 nmat 20 knots Endurance for

cruising speed

7 days 5 days Main engine

power

2 x 3645 kW

2 x 2880 Complement 42 kW

persons

55 person Ac (FPB 57) = Ac (KCR 60 M)

𝐴𝐶(𝐹𝑃𝐵−57)=∆_𝑆^2/3× 𝑉_𝑆³ 𝑃𝐵

ICMST 2019 August, 1 2019

𝐴𝐶(𝐹𝑃𝐵−57)= (378 𝑡𝑜𝑛)^2/3 𝑥 (28 𝑘𝑛𝑜𝑡) ³ 7290 𝑘𝑊

𝐴_{𝐶(𝐹𝑃𝐵−57)}= 174,90182

Tabel 3. Comparison of admiralty coefficients (DESPPC, PREDFDS,TRIBON and model test)

From Table 3. it is known that the value of the admiralty coefficient that approaches the FPB 57 coefficient value is 175.334311. The similarity of the admiralty coefficient between the results of the DESPPC program calculation and the FPB 57 shows that the calculation of the DESPPC program can be used as a basis for calculating the KCR 60 propulsion analysis.

3.4. Calculation of Powering KCR 60 M Using the MARIN DESPPC Program.

The output of this program is a propeller design and calculation of powering (shaft power) at draft 2.6 m. The design propeller is:

- Propeller: B-series

- Number of blades: 5 pieces (B5) - Propeller diameter (D): 1,800 m - Blade area ratio (AEAO): 1,411 - PDRA: 1,288

- Propeller rotation (n): 499,6rpm (8,3267rps) - Vs: 28 knots (14.4032 m / s)

Table 4. The results of the DESPPC power calculation on draft 2.6 m (full load).

VS THRUST N PS

[knots] [kN] [1/Min] [kW]

15.00 91.8 261.9 1128

15.50 97.0 270.0 1230

16.00 102.6 278.3 1343

16.50 109.2 287.0 1473

17.00 117.0 296.4 1627

17.50 126.5 306.5 1814

18.00 137.1 317.1 2028

18.50 148.6 327.9 2266

19.00 160.6 338.7 2521

19.50 172.3 349.2 2782

20.00 184.0 359.4 3052

20.50 195.6 369.5 3331

21.00 207.3 379.5 3620

21.50 218.9 389.2 3918

22.00 230.4 398.8 4224

22.50 241.9 408.3 4538

23.00 253.4 417.6 4860

23.50 264.9 426.8 5191

24.00 276.2 435.9 5528

24.50 287.5 444.9 5874

25.00 298.0 453.5 6211

25.50 306.9 461.5 6517

26.00 314.8 469.2 6806

26.50 322.0 477.1 7083

27.00 328.5 484.8 7351

27.50 334.4 492.3 7613

28.00 339.7 499.6 7869

28.50 344.6 506.7 8118

29.00 349.1 513.7 8360

29.50 353.3 520.5 8598

30.00 357.1 527.2 8830

The power is calculated using the B-series propeller according to the propeller output data from the DESPPC program. According to the B-series performance table for the number of blades (Z) equal to 5, then the maximum blade area ratio is 1.05. Thus to avoid / minimize errors, the propeller to be used on the KCR 60 M is:

- Number of blade: 5 pieces (B5) - Propeller diameter (D): 1,800 m

- Blade area ratio (AEAO): 1.05 (B5-105) - PDRA: 1,288

- Propeller rotation (n): 499,6rpm (8,3267rps) - Vs: 28 knots (14.4032 m / s)

- Wake friction (W) : 0,062 Advanced coefficient (J) is:

J = ^𝑉𝑎

𝑛𝑥𝐷 =^{𝑉𝑠𝑥(1−𝑤)}

𝑛𝑥𝐷

J = 14,4032𝑥(1−0,062)

8,3267 𝑥1,800 = 0,901

From the B-series B5-105 propeller performance diagram, we know that:

KT : 0,2334 KQ : 0,05138

0 : 0,6574

Fig. 4. Graph B5-105 propeller characteristic performance.

Then;

𝑇 = KT x ρ x n² x D⁴

𝑇 = 0,2334 x 1025 x 8,3267² x 1,800⁴ 𝑇 = 174.124,777 N

The total of thrust for 2 propellers is 348,256 kN and shows that the B5-105 thrust propeller can push the ship to reach a speed at 28 knots. The value of torque (Q) propeller B5-105 m:

𝑄 =Kq x ρ x n² x D⁵

𝑄 =0,05138 x 1025 x 8,3267² x 1,800⁵ 𝑄 =68,996 kN

then;

PDc = 2𝜋 𝑥 𝑄 𝑥 𝑛

PDc = 2 𝑥 3,14 𝑥 68.996,383 𝑥 8,3267 PDc = 3.607,937 𝑘𝑊

so that:

Ps = ^𝑃𝐷𝑐

𝜂𝑆 .𝜂𝐵

Ps =^7.215,874

0,98

Ps = 7.363,137 𝑘𝑊

By using a B5-105 propeller to reach a speed of 28 knots at draft 2.6 m the calculation of shaft power (Ps) is 7,363,137 kW. While the calculation of the DESPPC has a shaft power of 7869 kW. The

value difference is caused by two factors, namely the blade area ratio used by the program is different from the manual count and the manual calculation above uses the open water test characteristics while the program uses the propeller characteristics behind the ship.

3.5. Calculation of powering at draft 2.4 m (half load).

When the KCR carried out a retest of speed at 2.4 m (half load) with the use of 100% MCR engine power (PB = 5760 kW, PS = 5702.4 kW), the maximum speed achieved 23.3 knots, this is not in accordance with the design of the shipyard (PT X) that the calculation of TRIBON on the draft 2.4 M can reach speeds of 28 knots. To analyze these problems, ship power (PS) is calculated on draft 2.4 m using the DESPPC program.

Table 5. The calculation results of the power from the DESPPC on the draft 2.4 m (half load).

VS THRUST N PS

[knots] [kN] [1/Min] [kW]

15.00 78.9 265.5 917

15.50 83.5 273.8 1002

16.00 88.7 282.4 1098

16.50 94.7 291.6 1210

17.00 101.8 301.2 1342

17.50 110.7 311.8 1505

18.00 120.4 322.6 1685

18.50 129.9 333.1 1871

19.00 139.4 343.5 2066

19.50 148.9 353.6 2268

20.00 158.4 363.6 2477

20.50 167.9 373.4 2693

21.00 177.3 383.1 2915

21.50 186.7 392.6 3144

22.00 196.0 402.1 3379

22.50 205.3 411.3 3621

23.00 214.6 420.5 3868

23.50 223.8 429.6 4122

24.00 232.9 438.5 4380

24.50 241.8 447.3 4642

25.00 250.0 455.8 4895

25.50 256.7 463.5 5120

26.00 262.4 470.9 5331

26.50 267.7 478.1 5535

27.00 272.4 485.1 5730

27.50 276.6 492.3 5917

28.00 280.5 499.5 6102

28.50 284.1 506.6 6285

29.00 288.3 514.0 6485

29.50 293.6 522.2 6725

30.00 299.9 530.9 6996

From table 5. is known that shaft power (PS) is required at 6,102 kW. Propeller design used in the above conditions as follows:

- Type: B-series (B5-105)

ICMST 2019 August, 1 2019 - Number of leaves: 5 pieces (B5)

- Diameter of a propeller (D): 1.80 m - Blade area ratio (AEAO): 1,202 - PDRA: 1,218

- Propeller rotation (n): 499.5 rpm - Speed (VS): 28 knots

3.6 Analysis of Propeller Matching at draft 2.4 Meter

Based on the results of the 628 speed retest, on average loaded conditions of 2.4 m with engine power (PB) 100% MCR (PB = 5760 kW, PS = 5702.4 kW) the maximum speed of the vessel only reaches 23.3 knots. Therefore it is necessary to calculate the propeller performance installed to be compared with the B5-105 propeller

Table 6. Comparison of propeller performance installed on KCR 60 M with B5-105 propeller

Existing Propeller KCR 60 Comparison Propeller (B5-105) Propeller type PL 506 Propeller type B5-105 Number of blades 5 Number of blades 5

PDRA 1,460 PDRA 1,321

AEAO 1,06 AEAO 1,05

Diameter (D) 1,550 Diameter (D) 1,550 Propeller rotation (n) 693 rpm Propeller rotation (n) 589,9 rpm Data from Tribon Data from DESPPC:

Wake friction (w) 0,046 Wake friction (w) 0,069 Vessel speed 28 knots Vessel speed 28 knots

(14,4 m /s) (14,4 m/s)

Propeller rotation 693 rpm Propeller rotation 589,9 rpm

11,550 rps 9,832 rps

J = ^𝑉𝑎

𝑛𝑥𝐷 =^{𝑉𝑠𝑥(1−𝑤)}

𝑛𝑥𝐷

J = 14,4032 𝑥 (1−0,046) 11,55 𝑥 1,550

J = 0,767 we get:

KT: 0,160 KQ: 0,028

0: 0,695 𝑇 = KT x ρ x n² x D⁴

𝑇 = 0,160 x1025x11,55² x 1,550⁴ 𝑇 = 126,280 kN

then:

Q =Kq x ρ x n² x D⁵

Q = 0,028 x1025x11,55²x 1,55⁵ Q =34,253 kN

so:

PDc = 2π x Q x n

PDc= 2 x 3,14 x 34.253,453 x 11,55 PDc = 2.484,539 kW

PDc (2 prop)= 4.969,078 KW ηS . ηB = 0,98 so the shaft power (Ps) is:

Ps = ^PDc

ηS .ηB

Ps =^4.969,078

0,98

Ps = 5070,488 kW

J = ^Va

nxD =^Vsx(1−w)

nxD

J= 14,4032x(1−0,069) 9,832x 1,550 J= 0,879 we get:

KT: 0,2626 KQ: 0,05775

0: 0,6437 T = KT x ρ x n² x D⁴

T = 0,2626 x1025x9,832²x 1,550⁴ T = 150,186 kN

then:

Q =Kq x ρ x n² x D⁵

Q = 0,05775 x1025x9,832²x 1,55⁵ Q =51,194 kN

so:

PDc = 2π x Q x n

PDc= 2 x 3,14 x 51.193,885x 9,832 PDc = 3.160,964 kW

PDc (2 prop) = 6.321,928 KW ηS .ηB = 0,98 so the shaft power (PS) is:

Ps = ^PDc

ηS .ηB

Ps =^6.321,928

0.98

Ps = 6.451 kW

3.7. Engine propeller Matching at draft 2,4 Meter To optimize the engine installed in KCR 60 (MTU 4000M73L, PB = 2880 kW, PS = 2851.2 kW) to achieve maximum speed on the draft 2.4 m, engine propeller matching is necessary. The method used in conducting engine propeller matching is by taking into account the propeller load factor and engine load factor. The method is to place the propeller load (PLF) smaller than the engine load (ELF).

PLF < ELF Qxn³

ρxVa⁵< Pdxn² 2πxρxVa⁵ Where:

Q = Torque propeller (kN)

Va = Advanced speed of fluid flow in the stern of the ship (m / s)

ρ = density of seawater (1025 kg / m3) Pd = Power delivered (W)

n = propeller rotation (m / s)

Table 7. Comparison of the value of propeller load (PLF) and engine load value (ELF)

N (RPM)

VS

(knot) T (kN)

Q (kN)

PLF ELF PS

(kW)

309 15 41,04118 137,7386 0,0042 0,0224 454,5655 318,6 15,5 42,7885 145,9113 0,0048 0,0238 496,4974 328,6 16 44,82462 154,7306 0,0056 0,0253 543,0327 339,3 16,5 48,28004 165,3132 0,0066 0,0270 599,0646 350,7 17 53,0282 177,5232 0,0079 0,0289 664,9257 363,3 17,5 56,92507 192,4391 0,0095 0,0310 746,6912 376,3 18 61,09313 208,7358 0,0115 0,0332 838,9063 388,9 18,5 65,27077 224,8645 0,0137 0,0355 933,9879 401,3 19 70,04167 241,1627 0,0161 0,0378 1033,622 413,4 19,5 74,65173 256,9542 0,0188 0,0401 1134,51 425,2 20 79,3365 272,9882 0,0217 0,0424 1239,708 436,8 20,5 84,02432 289,0434 0,0249 0,0448 1348,429 448,3 21 88,77495 305,3186 0,0284 0,0472 1461,855 459,5 21,5 93,43661 321,3088 0,0322 0,0496 1576,85 470,6 22 98,14257 337,4576 0,0364 0,0520 1696,108 481,5 22,5 102,8109 353,492 0,0408 0,0544 1817,851 492,2 23 107,431 369,3774 0,0456 0,0569 1941,754 502,7 23,5 111,8016 384,4695 0,0505 0,0593 2064,206 513,3 24 116,5316 400,744 0,0561 0,0619 2196,952 524,5 24,5 121,8595 419,0198 0,0626 0,0646 2347,266 535,6 25 127,2519 437,4191 0,0696 0,0674 2502,192 545,7 25,5 131,8296 453,3223 0,0763 0,0699 2642,064 546,7 25,55 132,3023 454,8993 0,0769 0,0702 2656,114 555,2 26 135,9905 467,7467 0,0829 0,0724 2773,592 564,4 26,5 139,9465 481,5002 0,0896 0,0748 2902,457 573,2 27 143,5947 494,2398 0,0964 0,0772 3025,702 581,6 27,5 146,9199 505,9147 0,1030 0,0795 3142,563 589,9 28 150,827 516,5548 0,1098 0,0817 3254,446 598 28,5 154,7281 527,5132 0,1168 0,0840 3369,122 606,5 29 158,2172 539,846 0,1247 0,0864 3496,898 616 29,5 163,3782 555,534 0,1345 0,0891 3654,884 626,3 30 168,7866 574,0641 0,1460 0,0921 3839,946

Shaft Power (PS) Existings

:P_B× η_G(asumptionη_G= 0,99) : 2.880 × 0,99

: 2.851,2 kW

Power Shaft (PS) on matching point : 2.347,266 kW

: 2.347,266 kW 2.851,266 kW : 82,325 % MCR

Fig.5. Graph of comparison of propeller load value (PLF) and engine load value (ELF)

From Table 4.8 and figure 4.6 It can be concluded that the propeller operation point and machine operation (matching point) is at propeller rotation 524.5 rpm with shaft power (PS) of 2347,266 kW. This point represents the position of the engine load in the condition of service rating (82.325% MCR) with a speed that can be achieved which is 24.5 knots. While the maximum speed with a shaft power of 100% MCR is 26.30 knots.

3.8 Analysis of the Propeller Diameter Effect on Ship Velocity

The ideal propeller diameter of the ship is 0.6- 0.7 from the maximum draft of the vessel (Lewis, 1988). From the calculation of the DESPPC program at conditions loaded 2.6 m and 2.4 m and the use of

1.8 m and 1.550 m diameters are shown in the table below.

Table 8. Comparison of the use of B-series propellers (B5-105) with 1.8 m and 1.5 m propeller diameters

VS

(KNOTS)

SARAT 2,6 M

SARAT 2,4M Dia 1,800 m Dia 1,550 m Dia 1,800 m DAYA (PS) DAYA (PS) DAYA (PS)

15 1128 1005 917

15,5 1230 1098 1002

16 1343 1203 1098

16,5 1473 1326 1210

17 1627 1472 1342

17,5 1814 1654 1505

18 2028 1855 1685

18,5 2266 2063 1871

19 2521 2281 2066

19,5 2782 2506 2268

20 3052 2739 2477

20,5 3331 2979 2693

21 3620 3226 2915

21,5 3918 3481 3144

22 4224 3742 3379

22,5 4538 4010 3621

23 4860 4284 3868

23,5 5191 4565 4122

24 5528 4850 4380

24,5 5874 5142 4642

25 6211 5424 4895

25,5 6517 5678 5120

26 6806 5916 5331

26,5 7083 6145 5535

27 7351 6364 5730

27,5 7613 6572 5917

28 7869 6777 6102

28,5 8118 6978 6285

29 8360 7197 6485

29,5 8598 7460 6725

30 8830 7757 6996

From table 8, it can be seen that by using a 1.8 m diameter propeller it takes a smaller shaft power (PS) compared to using a 1.550 m diameter propeller to operate in either draft 2.6 m or draft 2.4 m. In accordance with the results of the DESPPC program data obtained by the propeller calculation as follows:

-Type propeller : B-series - Number of blades (Z) : 5 pcs - Propeller diameter (D) : 1,800 m - Blade area ratio (AEAO) : 1,411

-AEAO maksimum B-series : 1,05 (B5-105)

- PDRA : 1,288

- Propeller rotation(n) : 499,6 rpm(8,3 rps) - Velocity (Vs) : 28 knots (14,4 m/s

By using the propeller data above, it can be proven by calculating how the influence of the propeller when used in draft 2.4 meters) through the following calculations:

- Thrust at V 28 knot = 280,5 kN

ICMST 2019 August, 1 2019 - Propeller rotations (n) = 439,32 rpm (Propeller

rotations at draft 2,6 m)

- Vs (thrust 280,5 at draft 2,6 m) = 24,190 knots - Wake friction (W) = 0,063

The advanced coefficient at the speed of 28 knots is:

J = ^Va

nxD =^Vsx(1−w)

nxD

J= 12,443x(1−0,063)

7,322x1,800 = 0,8846

From the B-series B5-105 propeller performance diagram obtained:

KT : 0,263281 KQ : 0,05791

0 : 0,66 then:

T = KT x ρ x n² x D⁴

T = 0,263281 x 1025 x 7,322² x 1,800⁴ T = 151,877 kN

The amount of thrust for 2 propellers is: 303.754 kN..

This shows that the B5-105 thrust propeller is able to push the ship to a speed of 28 knots. The amount of torque (Q) propeller B5-105 is:

Q =Kq x ρ x n² x D⁵

Q =0,05791 x 1025 x 7,322² x 1,800⁵ Q =60,131 kN

so that:

PDc = 2π x Q x n

PDc = 2 x 3,14 x 60.131,135 x 7,322 PDc = 2.764,959 kW

The amount of propeller power (PDc) for 2 (two) propellers is 5,529.92 kW. Assuming shaft and bosing efficiency are 0.98, so:

Ps = ^PDc

ηS .ηB

Ps =^5.529,92

0,98

Ps = 5.642,774 kW

From the above calculation it is known that by using a B5-105 propeller with a diameter of 1,800 m to reach a speed of 28 knots at draft 2.4 m, shaft power (Ps) is needed at 5,642,774 kW. Taking into account the engine load factor must be greater than the propeller

load factor, then according to the results of the calculation of the DESPPC program the amount of shaft power (PS) to reach a speed of 28 knots is 6102 KW. For KCR 60 M with engine power (PB) installed 5760 kW (PS = 5702.4 kW), using a B5-105 propeller the maximum speed can reach 26.9 knots.