Experimental investigation on the cavity evolution and dynamics with special emphasis on the development stage of ventilated partial cavitating flow
Experimental investigation on the cavity evolution and dynamics with special emphasis on the development stage of ventilated partial cavitating flow
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空穴演化和动力学的实验研究，特别关注通风部分空化流的发展阶段
DOI：
10.1016/j.oceaneng.2019.106140
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发表时间：
2019
影响因子：
5
通讯作者：
Zong Zhi
中科院分区：
文献类型：
--
作者：
Sun Tiezhi;Zhang Xiaoshi;Xu Chang;Zhang Guiyong;Wang Cong;Zong Zhi
通气空泡流由于气液之间的强烈相互作用而具有复杂的流动特征和动力学特性。本文在哈尔滨工业大学封闭式水洞中对通气局部空化流动的发展阶段进行了实验研究。试验中，在试验段中部放置了一个头部带有通风槽的铝合金圆锥形轴对称试验体。使用高速摄像机来捕捉流态。试验模型中安装了5个压力传感器，用于测量非定常动压。建立了空化流场多场同步测量系统，研究了空化演化与瞬时压力的关系。研究了气体通风量对空泡演化和动压的影响。观察到三种非定常流态，即泡沫空腔（FC）、连续透明泡沫空腔（CTFC）和连续透明非对称空腔（CTAC）。此外，还观察到三个不同的空腔区域的基础上的动态空腔拓扑结构，被称为充气空腔区（GFCR），再入射流区（REJR）和尾流区（WR）。分析了部分通风空泡再入流动模型确定的气体卷吸机理。我们观察到的一个现象是，通风率的增加可以提高腔内的动态稳定性，并可以帮助减少测试体上的负载。此外，我们还发现，由于重入流的影响，在压力峰值和泡沫腔关闭位置之间存在空间位置间隙。
Ventilated cavitating flows involve complex features and dynamic characteristics due to the strong interactions between gas and liquid. In the present work, we especially focus on the experimental investigation of the development stage of ventilated partial cavitating flow in a closed-loop water tunnel at Harbin Institute of Technology. In the experiments, a conical axisymmetric test body made of aluminum alloy with a ventilation slot at the nose is placed at the middle of the test section. A high-speed camera is used to capture the flow patterns. Five pressure transducers are installed in the test model to measure the unsteady dynamic pressure. A multi-field synchronous measurement system for cavitating flow is established to address the relationship between cavity evolution and instantaneous pressure. The effect of gas ventilation rate on cavity evolution and dynamic pressure are investigated. Three unsteady flow patterns are observed namely foamy cavity (FC), continuous transparent and foamy cavity (CTFC), continuous transparent and asymmetric cavity (CTAC) respectively. In addition, three distinct cavity regimes are also observed based on the dynamic cavity topology, referred to as gas-filled cavity region (GFCR), re-entrant jet region (REJR) and wake region (WR). The gas entrainment mechanism determined by the re-entrant flow model of a partial ventilated cavity is analyzed. A phenomenon we observed is that the increase in ventilation rate can improve the dynamic stability inside the cavity and can help reduce the load on the test body. Moreover, we find that there are location gaps in space between the pressure peaks and the foamy cavity closure position due to the effect of re-entrant flow.