Submarine Propeller Noise Spectrum Analysis in Cavitation Tunnel in One-third Octave Filter

In military systems in order to Concealment naval vessels of weapons (missiles and torpedoes), be sure to check their audio frequency spectrum noises. Sources of noise, in the general case for marine vessels divided into three categories: hydrodynamic hull noise, machinery noise and noise from Propeller. Propeller noise impact is higher. cavitation and non_cavitation noise are different. Frequency spectrum analysis of global standards through octave filters are calculated. In this paper, received the noise of propeller at different speeds (200 to 2000 cycles Per minute) and constant pressure, with the high-sensitivity hydrophone and stored in the computer then with passes of octave filters is analyzed. Analysis of one-third octave band noise in three different tests. According to hydrophone distance to the propeller, propeller noise frequency spectrum in different periods have been mapped and compared. This analysis shows that periods of high-intensity noise in the bands 30 and 40 (frequency between 1000 and 10000) are more distributed.Based on the analyzes performed, the noise power spectrum in octave bands 40 to 42 are about 25 percent more than other bands, and increases as impeller speed increases. On the other bands these noise band are the musf effective bands on detection of torpedoes.