Hydro-acoustic performance

Abstract

The propulsor is the most important noise source. Low rotational speed and low tip speed are generally considered advantageous from a hydro-acoustic point of view. Hydroacoustic noise generated directly by a propulsor can be categorized into: cavitation noise; narrowband, (or tonal), noise; and broadband noise. It is noted that if cavitation occurs it will dominate all other sources of noise. Cavitation Inception Speed is the lowest speed at which cavitation will occur. Four different operating regimes can be identified: ultra-quiet operation at low speed; normal operation at patrol speed; high speed operation; and operation close to the surface when snorkeling.