전산 소음 해석 기법을 이용한 잠수함 표면 처리에 따른 소음 효과 관찰

Abstract

Submarine has been performed for national defense activities representatively as a multi-purpose underwater vehicle. Underwater Radiated Noise (URN) which emitted during underwater vehicle operation is directly related to the survivability of the underwater vehicle. This study focused on examining the effects of surface treatment on noise aspects in whole submarine body for the first time. Prior to the acoustic analysis on the submarine model, the acoustic analysis procedure using commercial CFD software was verified using a 2D cylinder model. Acoustic analysis on submarine model was conducted for two cases: smooth surface as a reference case, and a few micrometers of V-type applied riblet case. To solve the incompressible fluid flow passing the submarine, the Reynolds-averaged Navier-Stokes (RANS) equation coupled with the k-ω SST turbulence model was used. For acoustic analysis, the Ffowcs Williams and Hawkings acoustic analogy, which calculates flow-induced noise by designating a physical wall as a noise source, was used. The noise effects according to the surface treatment on submarine shape were examined by comparing overall sound pressure level (OASPL) between smooth and riblet case and the results indicate that noise around submarine shape was reduced about 4.3 dB in maximum on surface-treated area. However, when calculating OASPL excluding noise below 20 Hz, which is a frequency range where noise does not propagate, the noise tends to increased due to riblet shape. This study provides established procedure in acoustic analysis on whole submarine body and a new perspective that underwater radiation noise should be considered when designing surface treatment on submarine.