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3차원 수중익에서 공기분사에 의한 캐비테이션 및 소음특성 연구
설한신,정홍석,Seol, Hanshin,Jeong, Hongseok 한국음향학회 2021 韓國音響學會誌 Vol.40 No.1
In this study, changes in cavitation pattern and noise by air injection were investigated experimentally in a cavitation tunnel. Air injection system that can control the location and the amount of air was manufactured and installed in an elliptic wing that exhibits similar characteristics to those of a propeller blade. Various types of cavitation were simulated on the hydrofoil by adjusting the test conditions in the cavitation tunnel, and the changes in cavitation pattern and noise according to air injection were experimentally analyzed. It was shown that the noise characteristics varied depending on the position and the amount of air injection. This means that in order to apply the air injection technology to the propeller, it is necessary to optimize the air injection location and the amount of injection according to the cavitation characteristics.
질소산화물 저감을 위한 SCR TYPE CEM의 설계평가
정석윤(Seokyoon Jeong),정홍석(Hongseok Jung),이근우(Kunwoo Yi),조연근(Yonguen Cho),김경훈(Kyunghun Kim),김혜삼(Hyesam Kim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
SCR system for diesel engine vehicles is a device to reduce NOx from the emission gas of the diesel engine causing selective catalytic reaction by utilizing a metal catalyst with ammonia, NH₃, or HC as a reductant, and the device is recognized as a unique technology to meet future emission regulation for NOx such as Euro-V (2008). Under the current circumstance that the development for diverse post process technologies is in process, in this study, we evaluated the pressure and uniformity inside of SCR TYPE CEM(Catalyst Exhaust Muffler) reducing NOx among noxious gasses, through design and CFD(Computational Fluid Dynamics) analysis.
하준범,구가람,정철웅,설한신,정홍석,정민석,Ha, Junbeom,Ku, Garam,Cheong, Cheolung,Seol, Hanshin,Jeong, Hongseok,Jung, Minseok 한국음향학회 2022 韓國音響學會誌 Vol.41 No.3
In this study, each component of flow noise source of underwater propeller installed to the scale model of the KVLCC2 is investigated and the effect of each noise source on underwater-radiated noise is quantitatively analyzed. The computation domain is set to be the same as the test section of the large cavitation tunnel in the Korea Research Institute of Ship and Ocean Engineering. First, for the high-resolution computation of flow field which is noise source region, the incompressible multiphase Delayed Detached Eddy Simulation is performed. Based on flow simulation results, the Ffowcs Williams and Hawkings integral equation is used to predict underwater-radiated noise and its validity is confirmed through the comparison with the tunnel experiment result. For the quantitative comparison on the contribution of each noise source, the spectral levels of sound pressure and power levels predicted using propeller tip-vortex cavitation, blade surface and rudder surface as the integral region of noise sources are investigated. It is confirmed that the cavitation which is monopole noise source significantly contributed to the underwater-radiated noise than propeller blades and rudder which is dipole noise source, and the rudder have more contribution than propeller blades due to the influence of the propeller wake.