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FW-H 방법을 이용한 잠수함 표면 처리에 따른 소음 전산 해석
김승기(Seunggi Kim),유재영(Jaiyoung Ryu) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Submarine has been performed for national defense activities representatively. 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 submarine. Numerical simulations were conducted for two cases : smooth surface as a reference case, and V-type riblet. To solve the incompressible fluid flow passing the submarine, the Reynolds-averaged Navier-Stokes equation coupled with the k-ω SST turbulence model was used. As a result of examining the noise radiation around the submarine, it was confirmed that it was necessary to pay attention to the noise radiation effect in the middle part of the submarine body. And the results indicate that overall sound pressure level can be reduced about maximum 4 dB at far-field by applying riblet surface. This study provides more enhanced understanding about the surface design on underwater vehicles to reduce underwater radiated noise.
전산 소음 해석 기법을 이용한 잠수함 표면 처리에 따른 소음 효과 관찰
김승기(Seunggi Kim),유재영(Jaiyoung Ryu) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.4
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.
정우열(Wooyeol Jeong),오세민(Semin Oh),김승기(Seunggi Kim) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
Apart from existing approaches that simply count seconds after a driver steps off the brake pedal, an active EHS system calculates torque delivered to wheels. When the torque reaches a point where a vehicle does not roll back on a hill, it releases the brake. As the number of AMT vehicles that drivers cannot manipulate clutch pedal increases, EHS system becomes essential these days especially for commercial vehicles. This paper describes Active EHS system logic and its verification by comparing vehicle CAN data and logic results.