基于短时傅立叶变换的空蚀噪声分析  

Cavitation noise analyses based on short time Fourier transform

作　　者：葛晗[1] 秦力[1] 颜大运[1] 陈大融[1] 

机构地区：[1]清华大学摩擦学国家重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2010年第7期1029-1031,1036,共4页Journal of Tsinghua University(Science and Technology)

摘　　要：空化过程中,固体近壁面溃灭的空泡会对固体壁面形成短时的高速高压冲击,并辐射出强烈的噪声。针对这一特点,该文采用短时Fourier分析方法(STFT)对空蚀噪声信号进行时频域的分析,表征出了黄铜在振动空蚀各阶段的频谱特征。随着空蚀阶段的发展,信号主要在4 kHz以上的频段发生变化。在空蚀初生期,频率在时间轴上不均匀分布;在上升期和稳定期,频率在时间轴上的分布逐渐均匀,并且声压升高;在衰减期,4 kHz以上的频率急剧减少,声压也显著降低。分析结果为研究不同空蚀阶段下的空蚀噪声特征提供了一种分析方法。During cavitation,the bubbles collapse creates a micro-jet which impacts the nearby solid wall at high pressures and high speed which creates noise.The short time Fourier transform（STFT） was used to analyze frequency variations during the entire cavitation erosion process.For brass,frequencies above 4 kHz represent different cavitation erosion stages.Initially,frequencies above 4 kHz are unevenly distributed in time.As the cavitation erosion develops,the frequencies become more even and the sound pressure becomes higher than initially.In the attenuation stage,the pulse suddenly decrease due to a significant decrease in the sound pressure level.These significant changes show that this method offers a new useful noninvasive method for cavitation erosion monitoring.

关 键 词：空蚀噪声 短时傅立叶 频谱分析 空泡 冲击 

分 类 号：TH7[机械工程—仪器科学与技术]