Spectral Characteristics of Sheet/Cloud Cavitation
Spectral Characteristics of Sheet/Cloud Cavitation
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DOI：
10.1115/1.1287854
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发表时间：
2000-09
影响因子：
2
通讯作者：
M. Kjeldsen;R. Arndt;Mark Effertz
中科院分区：
文献类型：
--
作者：
M. Kjeldsen;R. Arndt;Mark Effertz
空化现象是通过一个安装在特殊设计的水洞中且配备大量仪器的二维NACA 0015水翼进行观测的。研究发现，空化的动态特性随攻角和空化数α的不同组合而有很大差异。在较大攻角时，观察到两种类型的流动不稳定性。在低空化数时，云状空化的低频脱落导致升力和压力脉动（Δp）在基于弦长的斯特劳哈尔数fc/U约为0.15时产生强烈振荡。该频率对空化数的变化相对不敏感。随着空化数的增加，振荡的谐波成分发生显著变化。注意到在高得多的频率处出现一个频谱峰值，其频率几乎随空化数线性增加。在升力波动中也观察到类似的行为。
Cavitation observations were made using a highly instrumented 2D NACA 0015 hydrofoil mounted in a specially designed water tunnel. It was found that the dynamic characteristics of the cavitation vary considerably with various combinations of angle of attack and cavitation number, a. At higher angles of attack, two types of flow unsteadiness are observed. At low σ, a low frequency shedding of cloud cavitation results in a strong oscillation in lift and Ap at a Strouhal number, based on chord length, fc/U, of about 0.15. This frequency is relatively insensitive to changes in a. As a is raised, the harmonic content of the oscillations changes significantly. A spectral peak at much higher frequency is noted that increases in frequency almost linearly with cavitation number. Similar behavior is noted in the lift fluctuations