The characteristics of unsteady cavitation flow under different cavitation numbers are investigated experimentally. An optical test rig is designed to visualize the cavitation flow and the cavity length is defined based on high-speed camera technology. The development of cavitation flow can be divided into inception and fusion region, expansion region and collapse region. Due to the interaction between the re-entrant jet and the cavity interface, the cavitation bubbles near the solid wall collapse earlier than them in the downstream. The cavitation number is also the important factor determining the cavity length pulsation. Further analysis shows that the smaller the cavitation number, the smaller the frequency of cavity length fluctuations and the larger the mean cavity length. The cavitation intensity is stronger at lower cavitation number. Meanwhile, the cycle collapsing frequency of cavitation is around 220–320 Hz. With the decrease of cavitation number, the amplitude of cavitation pulsation increases while the corresponding collapsing frequency decreases.

实验研究了不同空化数下非定常空化流动的特性。光学测试台旨在可视化空化流动，并基于高速相机技术定义空腔长度。空化流的发展可分为起始融合区、膨胀区和坍塌区。由于折返射流与空腔界面之间的相互作用，固体壁附近的空化气泡比下游的空化气泡更早坍塌。空化数也是决定空腔长度脉动的重要因素。进一步分析表明，空化数越小，腔长波动频率越小，平均腔长越大。空化数越低，空化强度越强。同时，空化的循环崩溃频率约为 220-320 Hz。随着空化数的减少，空化脉动的幅度增大，而相应的坍缩频率减小。