Acoustic Signature Analysis and Numerical Simulation on Radiated Noise of Underwater Contra-rotating Propellers

The noise of contra-rotating propellers contributes a major part to the underwater vehicle. The special noise properties often become an important basis for detecting and identifying targets. This paper establishes the numerical simulation and calculation approach on the radiated noise properties of contra-rotating propellers, which was set up based on the theory of acoustic analogy and the large eddy simulation approach, and then the numerical simulation results are verified. Taking the DTMB contra-rotating propellers which consist of DTMB3689 and DTMB3849 as an example, the numerical calculation of the hydrodynamic performance of the contra-rotating propellers is carried out based on the solving method of Reynolds stress turbulence model and the results agree well with the experimental results. The disk velocity distribution, blade pressure distribution and hydrodynamic wake distribution of the contra-rotating propellers are analyzed. Analyzing the acoustic signature of contra-rotating propellers shows that the low frequency line spectrum not only reflects the multiplicative frequency feature, but also the additive frequency feature, and the relationship between the radiated noise of the contra-rotating propellers and its inherent structure and its motion state is correlated.