The test section of this tunnel is rectangular with a length of 2.6 m, a width of 0.6 m and a height Selleckchem PD0325901 of 0.6 m. The maximum flow speed is 12 m/s, and the pressure can vary from 10 to 200 kPa. A schematic diagram of the MOERI medium-sized tunnel is shown in Fig. 7. A wake screen composed of a brass wire mesh was made to reproduce the nominal wake flow measured

behind the model ship in the MOERI towing tank. The propeller configurations and the nominal wake distributions measured at the propeller plane inside the cavitation tunnel are shown in Fig. 8. The pressure fluctuation is measured on a flat plate above the model propeller. The flat plate is away from the model propeller tip, which corresponds to the vertical clearance selleck chemical of the hull. Pressure transducers, model XTM-190-25A, were used to measure the pressure values. The computation and the five measured positions on the plate are shown in Fig. 9. Using the method recommended by ITTC (1987), the full-scale pressure fluctuation amplitudes can be predicted from the model scale measurement according to the following formula. equation(9) PS=PM×ρSρM(nSnM)2(DSDM)2fSfM=nSnMwhere ρρ is the density, nn is the rotational speed, and D is the diameter; suffix S represents the ship, and M represents the model.

The cavitation patterns of the model propellers are obtained for the selected blade′s angular position, and the corresponding numerical flow analysis results are shown in Fig. 10, Fig. 11 and Fig. 12. The angular positions of a key blade shown in these figures are measured from the vertically upward position in a clockwise direction when the propeller is viewed from behind. Fig. 13 shows the computed sheet cavitation volume variations. Fig. 14, Fig. 15 and Fig. 16 are the comparison results. The experimental result, the potential-based prediction results, and the results of the newly developed time domain prediction method are compared at positions ‘P’, ‘C’, and ‘S’. As shown Table 4 and Fig. 17, the maximum value of the pressure fluctuation is experimentally measured

and numerically predicted at a slightly starboard side of the propeller. There are two reasons. The first reason is that sheet cavitation volume is occurred analogously symmetric shape whose maximum volume is located slightly starboard side as shown in Fig. 13. The second reason is Bumetanide the source movement. Because sources are moving from port side to starboard side, induced pressure fluctuation at the starboard side is higher than that of port side. The newly developed time domain prediction results show good agreement with the experimental results, and the developed method is qualitatively and quantitatively superior to the potential-based prediction method. A new time domain prediction method has been presented with the aim of computing the pressure fluctuation induced by a propeller sheet cavitation. Modern acoustic theory is applied to the source modeling of the pressure fluctuation.