非定常空化流动研究现状与进展

针对非定常空化流动数值计算模型,总结了不同汽液相间传输模型对模拟空穴发展和空泡脱落过程的影响,发现不同空化模型对于非定常空化流场的不同区域的预测有着明显的差异.建立了一种基于混合密度分域的空化流动计算模型,合理预测了空泡脱落时刻翼型尾部的不稳定脉动区.通过考虑空化流动的湍流多尺度与多相局部可压缩特性,提出了一种基于混合密度分域的混合湍流模型,预测结果与试验结果吻合更好.综合回顾试验与数值计算方面的研究工作,围绕空化流动特性与动力学问题,主要从非定常流场空穴形态、流动结构、空化流体动力等几个方面对非定常空化流动机理及相应研究成果进行了较为详细地评述和讨论.最后,基于非定常空化研究的发展趋势和进一步研究可能面临的突出问题,对非定常空化流动研究的发展方向进行了探讨与展望.

Progress and prospects of investigation into unsteady cavitating flows

In view of numerically computational models for unsteady cavitating flows, influences of mass transfer model between liquid and vapor phases on cavity development and vortex shedding were summarized. It was identified that cavitation models could produce significant different predictions in different cavity regimes. A density correction-based cavitation model(DCCM)has been proposed in our group, as a result, the unsteady pressure fluctuation characteristics in the wake of a hydrofoil was predicted reasonably well. By considering the multi-scale turbulence structure and local compressibility, a filter-based density correction turbulence model(FDCTM)was put forward and a better prediction was achieved against experimental data. Further, unsteady cavitating flow mechanisms were reviewed and discussed in detail based on existing experimental and simulation efforts on such flows by accounting for cavity shape, flow structure and hydrodynamic force from a cavitating flow characteristic and hydrodynamics point of view. Finally, based on the development tendency of investigation into unsteady cavitating flows and important problems potentially encountered in such a research, specific development directions were debated and prospected.