绕振动水翼空化发展及水动力学特性研究

Cavitation development and hydrodynamic characteristics around oscillating hydrofoil

采用FBM湍流模型和Zwart空化模型对绕NACA0015型振动水翼的非定常空化流场进行了数值模拟,分析了处于不同的振动条件下、不同空化数的水翼周围空化现象的发展过程,并对水翼振动过程中的水动力特性与流场结构变化做出分析,结果表明:前缘涡对片空化发展的影响较大,前缘涡的存在会使空穴尾缘靠近翼型壁面侧出现反向射流,由于反向射流,片空穴的形状尺寸将会在一定范围内波动。在前缘涡与尾缘涡的相互作用下,反向射流沿翼型表面向其前缘移动,最终使前缘处附着的空穴发生剪切而断裂成两部分,并使依旧附着在水翼表面的空穴主体部分的发展速度减缓。振动水翼由于前缘涡与大尺度空穴的分离脱落导致了翼型水动力曲线出现波动,这是影响水翼水动力特性的主要因素。

Here,unsteady cavitating flow field around NACA0015 oscillating hydrofoil was numerically simulated by using FBM turbulence model and Zwart cavitation model.The development process of cavitation phenomenon around the hydrofoil under different oscillation conditions and different cavitation numbers was analyzed,and hydrodynamic characteristics and flow field structure changes in hydrofoil oscillation process were analyzed.The results showed that leading edge vortex greatly affects development of sheet cavitation,existence of leading edge vortex can cause reverse jet to appear at cavity trailing edge near airfoil wall side;due to reverse jet,shape and size of sheet cavity can fluctuate in a certain range;under interaction between leading edge vortex and trailing edge vortex,reverse jet moves along airfoil surface to its leading edge,and finally reverse jet makes cavity attached at airfoil’s leading edge be sheared and broken into two parts,and development speed of main part of cavity still attached at the hydrofoil surface be slowed down;separation and shedding of leading-edge vortex and large-scale cavity can cause hydrodynamic curve of oscillating hydrofoil to fluctuate,this is the main factor affecting hydrodynamic characteristics of hydrofoil.