大侧斜桨非定常空化流动结构的数值研究

为了对船后螺旋桨空化流动问题进行深入分析,本文基于大涡模拟(LES)方法和Zwart空化模型对非均匀来流条件下的大侧斜桨非定常空化演变及空化对桨叶周围流动结构的影响进行了研究.首先,采用三套系统加密的网格对非均匀流场中螺旋桨空化流动计算结果进行网格无关性验证以及不确定度分析,结果表明计算方法的可行性和可靠性较高.其次,深入分析了不同时刻空化演变过程的桨叶周围流动结构,结果表明大侧斜桨发生空化时,桨叶表面主要会有回射流、主流和梢涡等流动结构,并且随着空化逐渐向叶稍收缩推移,少量的片空化在叶梢附近被回射流抬升并被卷吸进入梢涡中.此外桨叶推力沿径向的分布结果分析表明,由于桨叶载荷在叶稍处得到了很好的卸载处理,因此梢涡空化强度较低.

Numerical Research on Cavitation Flow Feature of a Highly Skewed Marine Propeller

In order to conduct an analysis of the cavitation flow of the propeller behind the ship,this paper uses the Large eddy simulation(LES)method and the Zwart cavitation model to numerically predict the cavitation evolution characteristics around a highly skewed marine propeller and effect of the cavitation on the flow feature under the condition of non-uniform inflow.Firstly,three sets of system refined grids are used to verify the grid independence and uncertainty analysis of the predicted results of the propeller cavitation flow in the non-uniform flow field.The results show that the calculation method is feasible and reliable.Secondly,an in-depth analysis of the flow details around the blade during the cavitation evolution process show that the flow structures such as re-entrant jet,main flow and tip vortex occur on the blade surface.And as the cavitation gradually shrinks to the blade tip,a small amount of sheet cavitation is lifted by the re-entrant jet near the tip and is entrained into the tip vortex.In addition,the results of the radial distribution of the blade thrust show that due to the blade load is well unloaded at the blade tip,the tip vortex cavitation strength is poor.