INVESTIGATION OF SUBMARINE PROPELLER VIBRATION NOISE POLLUTIONS ON THE TRACKING AND POINTING SYSTEM BY SPECTRUM TRANSFORMATION

摘要

In this study a DARPA Suboff submarine with a similar E1619 propeller at a constant rotating speed of 500 r/min has been numerical simulated by using 3D unsteady Reynolds-averaged Navier-Stokes (URANS) and turbulence closure equations. Firstly, flow field evolutions, hydrodynamic characteristics have mainly been discussed. Secondly, through spectrum transformation between two different coordinates, the submarine torque fluctuations have been transformed to azimuth and pitch angles in optic axis coordinate. Then they have been used as input signals sent to the transfer function of the tracking and pointing system. The results show that the main frequency in submarine torque fluctuation spectrums is keeping the same as the propeller rotation frequency in earth coordinate. But when it transformed to optic axis coordinate besides the propeller frequency's noise pollutions, there are many extra-frequencies noise appear. The results show that the final output error of submarine-based tracking and pointing system is significantly affected by submarine's pitch torque as well as the selected reference system. The amplitude and phase difference between the pitching and yawing torques also release a certain effect on the spectrum characters of transformed azimuth angle and output errors.