Trans RINA, Vol 153, Part A4, Intl J Maritime Eng, Oct-Dec 2011 Transducer
Original VG
A 3.151
New VG 2.912 %
7.5 reduction Table 1: Tabular comparison of pressure reduction between original VG and new VG design as per Figure 17 data. B 3.268
2.303 29.5
C 1.583
1.041 34.2
D 3.782
3.269 13.6
E 4.156
2.955 28.9
F 1.825
1.433 21.5
G 4.064
3.382 16.8
H 3.829
2.600 32.1
Figure 18: BPF components reduced by up to 52% with the installation of Vortex Generators. Measurement in the Steering Gear Room.
. In order to optimize the VG design, further CFD
investigation was carried out. Through systematic flow field simulations and comparisons, a new VG location on port side was proposed (see Figure 15). Compared to the original design, the new VG was moved down and forward away from the cooling water discharging hole. Also, as indicated in Figure 15, due to the effect of new VG location adjustment, streamlines of the cooling water jet were flown away from the critical 12 o’clock position of the propeller disk and the flow went downward and further away from the propeller disk, at approximately 6 o’clock of the propeller tip area.
Finally, to evaluate the actual performance of the latest design, cavitation tunnel tests were carried out to observe
the propeller cavitation pattern and to measure magnitude of the hull pressure impulse. The similarity law for propeller cavitation inception and growth is considered to have been met and the propeller cavitation number between cavitation tunnel considered equivalent.
test and sea trials was
Figure 16 shows the comparison results of blade cavity patterns between the original VG and new VG designs, as observed from the cavitation tunnel test. As seen, cavitation volume for the new VG design reduces at the critical area, at around 12 o’clock position (0o degree). Since cavitation volume is closely related to wake quality, cavitation decrease implies that the wake quality is improved by the new VG location adjustment.
©2011: The Royal Institution of Naval Architects
A-271
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64