空化噪声量测结构的声学性能研究

本文从理论上分析了在水流空化声测研究中空化噪声量测结构的声学性能。提出了判断空化噪声传声窗声学性能的两个条件,第一,工作液体和传声窗特性阻抗匹配条件:ρ_1C_1=ρ_2C_2;第二,空化噪声谱频域的最大频率f_(max)(或最小波长λ_(min))条件:f_(max)≤C/(60D)(或λ_(min)/D≥60)。若传声窗满足其中任一条件,就可以获得较好的声测效果。同时,对此结果进行了试验验证,试验结果和理论分析结果吻合很好。 根据这两个条件,本文对目前常规使用的有机玻璃传声窗的声学性能进行了分析。结果表明:对于清水空化的声测研究而言,其阻抗比r_(21)=2.18,不满足ρ_1C_1=ρ_2C_2条件,而且实际空化噪声谱频域很难满足f_(max)≤V/(60D)条件。因此,有机玻璃材料传声窗的传声效果并不理想,其声学性能不如聚乙烯材料更好。

On Acoustic Performance of Measuring Structure for Cavitation Noise

The acoustic performance of measuring structure for cavitation noise is theoretically analysed and the two criteria of the acoustic performance of STW (sound transmission window)are presented in this paper. One is the impedance matching condition between working liquid and STW, the other is the maximum frequency (or the minimun wave length) condition of cavitation noise spectrum. The theoretical results are verified by experiments.The performance of routinely used polymethyl-methacrylate STW is also analysed.