High-speed underwater vehicles are subjected to complex multiphase turbulent processes, such as the growth, development, shedding, and collapse of cavitation bubbles. To study the cavity evolution and pressure pulsation characteristics, in this paper, cloud cavitation over a conical axisymmetric test body with four pressure sensors is investigated. A multi-field simultaneous measurement experiment method for the natural cavitation of underwater vehicles is proposed to understand the relationship between cavity evolution and instantaneous pressure. The results show that the evolution of cloud cavitation can be mainly divided into three stages: (I) the growth process of the attached cavity, (II) the shedding process of the attached cavity, and (III) the collapse of detached cavities. The evolution of the attached cavity and collapse of the large-scale shedding cavity will cause strong pressure pulsations. It is found that the cavitation number plays an important role in cavitation evolution and pressure pulsation. Interestingly, as the cavitation number decreases, the fluctuation intensity of cavitation increases significantly and gradually presents obvious periodicity. Moreover, the unstable cavitating flow patterns are highly correlated with the time domain and frequency domain characteristics of pressure. Especially, as the cavitation number decreases, the main frequency becomes lower and the pressure band becomes more concentrated.

中文翻译：

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天然云非定常空洞的实验研究：空蚀数对空洞演化和压力脉动的影响

高速水下航行器要经受复杂的多相湍流过程，例如空化气泡的生长，发展，脱落和破裂。为了研究腔体的演化和压力脉动特性，本文研究了带有四个压力传感器的圆锥形轴对称测试体上的气蚀现象。提出了一种用于水下航行器自然空化的多场同时测量实验方法，以了解空洞演化与瞬时压力之间的关系。结果表明，云空化的演化主要可分为三个阶段：（一）附着腔的生长过程；（二）附着腔的脱落过程；（三）分离腔的塌陷。附着腔的演变和大规模脱落腔的塌陷将引起强烈的压力脉动。发现空化数在空化演变和压力脉动中起重要作用。有趣的是，随着空化次数的减少，空化的波动强度显着增加并逐渐呈现出明显的周期性。此外，不稳定的空化流型与压力的时域和频域特征高度相关。特别是，随着空化次数的减少，主频率降低，压力带更加集中。随着空化次数的减少，空化的波动强度显着增加并逐渐呈现出明显的周期性。此外，不稳定的空化流型与压力的时域和频域特征高度相关。特别是，随着空化次数的减少，主频率降低，压力带更加集中。随着空化次数的减少，空化的波动强度显着增加并逐渐呈现出明显的周期性。此外，不稳定的空化流型与压力的时域和频域特征高度相关。特别是，随着空化次数的减少，主频率降低，压力带更加集中。