The Analysis Of Flow Noise And Cavitation Property Of Underwater Appendage

The flow field which is around the underwater appendages has a great impact on their hydrodynamic performance, as a result of the irregular turbulent, vortex and cavitation, they will scour the junction and damage the structure. They also can generate flow noise and induce vibration of the structure. The collapse of the cavitation would erode the propeller, generate strong radiation noise, and affect the hydrodynamic performance. Therefore, the study of the underwater-body's flow field, and on this basis, it will be very helpful to use numerical simulation to obtain more precise information of sound field and the property of the cavitation. It's also very important to design low resistance, high performance and quiet underwater-body.There are three parts in this paper, namely, the calculation and study of the flow field; the numerical simulation of flow noise of the underwater appendage; the design and property analysis for foil sections of cavitating propeller.In the calculation of the flow field, select the junction model, which has more complexity of the flow field, but more sufficient information of experimental data. The turbulent model RNGκ-εwas used, and select air as material. It can get the distribution of pressure, velocity, and the property of the flow field, such as the secondary flow and junction vortex.Based on the calculation of the flow field, the FW-H model which developed by Lighthill's acoustic analogy theory, Lilley's broadband noise source models can both be used to calculate the flow noise. To analysis of the sail appendage which has a great impact in submarine, the sound pressure level was used.There are two main models were used to calculate the cavitation: one is bubble two-phase flow (BTF) model, and the other one is full cavitation model. The flow around the axis-symmetrical was simulated, and the both two cavitation models were used. The result can be compared with the data of experiment, and the full cavitation model is effective. Further by study of dual-cavitating propeller, a new propeller foil section was designed. It's used the full cavitation model by Singhal, and calculated the cavitation fraction and the ratio of lift and resistance of the foil section.