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원추형 오리피스의 유출계수와 캐비테이션에 관한 실험적 연구
김병찬,윤병옥,박복춘,조남오,지대성,정백순,박경암,Kim, Byeong-Chan,Yun, Byeong-Ok,Park, Bok-Chun,Jo, Nam-O,Ji, Dae-seong,Jeong, Baek-Sun,Park, Gyeong-Am 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.10
The high pressure drop is frequently required in the by-pass line of the pump or of the heat exchanger in power plants. However, cavitation produced by a high pressure drop could damage the pipe and pump blades. Conical orifices are adopted to reduce cavitation due to high pressure drop. The discharge coefficients of conical orifice plates were measured by weighing method in the standard water flow system. The discharge coefficients were larger when the ratios of thickness of orifice edge to throat diameter were larger. The noise generated from a conical orifice due to cavitation was measured with a sound level meter and a hydrophone. With increasing the bore diameter of the orifice, the sound pressure level or the noise level due to cavitation became higher. The noise level was suddenly increased at the inception of cavitation.
단위 충격 응답함수를 이용한 원형관 시스템의 누출감지 연구
전오성,윤병옥,김창호 한국소음진동공학회 1994 소음 진동 Vol.4 No.3
A method of the leak detection from the pipe system by using accelerometer is proposed. The signal detected from accelerometer is proved experimentally to be a dispersive wave. Based on the experiments, a method using the narrow band pass filter and the unit impulse response function is analyzed. The method uses the characteristics of the unit impulse response function, that the function is available evenin the narrow band signal because, unlike the cross correlation, it is normalized by the auto spectrum. The accelerometer is quite easier to use than the hydrophone in adapting to the pipe system.