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采用数值和实验相结合的方法研究了绕轴对称体三维非定常空化流动现象。实验中,采用高速摄像的技术和动态测力系统对绕半球型和平头型轴对称体的非定常空化流场及其动力特性进行了分析,观察了在不同空化数下,绕半球型和平头型轴对称体的空泡形态;测量了轴对称体受到的阻力,并对阻力信号进行了时频分析,得到了在非定常空化阶段,轴对称体动力特征频率。基于实验现象,发展了一种基于密度修正的分域空化流动的计算方法,并与实验结果进行了对比,结果表明:该方法可以较好的模拟绕轴对称体三维非定常空化流动现象。绕不同头型轴对称体的空化流场结构均存在明显的三维非定常流动特性,并且,空化流场形态与动力特征频率存在高度的相关性,不同头型轴对称体的非定常空化流场结构存在较大的差异,半球型轴对称体空泡流动的脉动主要是空泡尾部的高频小脱落引起的,而平头型轴对称体的空泡流脉动成分主要是大尺度的漩涡空泡团的周期性脱落。
The three-dimensional unsteady cavitation flow around an axisymmetric body was studied by a combination of numerical and experimental methods. In the experiment, the unsteady cavitation flow field and its dynamic characteristics of the hemispherical and flathead-type axisymmetric bodies were analyzed by using high-speed camera technology and dynamic force measurement system. The effects of hemispherical The shape of hollow head of axisymmetric body was measured. The resistance of axisymmetric body was measured, and the time-frequency analysis of resistance signal was carried out. The dynamic characteristic frequency of axisymmetric body was obtained in unsteady cavitation phase. Based on the experimental phenomena, a new method for calculating cavitation flow in subzones based on density correction was developed and compared with experimental results. The results show that this method can simulate well the three-dimensional unsteady cavitation flow around axisymmetric bodies . There are obvious three-dimensional unsteady flow characteristics around the cavitating flow field structures with different head-axis symmetry bodies, and there is a high correlation between the cavitation flow field shape and the dynamic characteristic frequency. The unsteady The structure of the flow field is quite different. The pulsation of the hemispherical axial symmetric body cavity flow is mainly caused by the high-frequency small exfoliation of the tail of the hollow tube. The pulsating components of the hollow axial flow symmetry body are mainly large-scale Whirlpool Cyclical cyclical shedding.