Detection of Cavitation with Directional Microphone Placed outside Piping
Cavitation-induced vibration and the consequent erosion of pipes are the potential damaging factors in the piping systems. In order to prevent them, it is desirable to develop a detection method for cavitation occurrence. In power plants, it is especially necessary to detect cavitation from outside the piping during operation. Therefore, we have investigated the cavitation detection methods using accelerometers and microphones placed outside the piping in a power plant. In this paper, to detect cavitation occurrence, we carried out cavitation noise measurements using directional microphones, and evaluated the flow-directional distribution of noises and frequency characteristics. Then we compared the RMS values of the directional microphone outputs obtained upstream and downstream from an orifice, and confirmed that the microphone output RMS ratio upstream and downstream from the orifice changed according to the cavitation states. Microphones had much lower sensitivity than accelerometers, but great improvement was obtained by directional microphones rather with non-directional microphones. To use the microphone output RMS ratio upstream and downstream from the orifice, measurements are needed at plural locations, but a data base to judge cavitation stages is not required and the ratio can be applied to detect cavitation phenomena in an operating plant.
cavitation power plant pipeline component orifice detection microphone
Yukinori NAGAYA Michio MURASE
Institute of Nuclear Safety System, Incorporated 64 Sata, Mihama-cho, Mikata-gun, Fukui 919-1205, Japan；Graduate School of Engineering, University of Fukui 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan
国际会议
上海
英文
890-899
2010-10-10（万方平台首次上网日期，不代表论文的发表时间）