水翼三维非稳态空化流动特性数值研究

Numerical Study on Three-Dimensional Unsteady Cavitation Flow Characteristics of Hydrofoil

为分析水翼绕流速度对非稳态空化现象的影响规律以及水翼空化过程演变机理,对NACA6408水翼空化过程进行了三维数值模拟计算,研究了不同绕流速度工况下水翼不同位置的压力、湍动能、速度等参数的变化规律,分析空化现象的周期性发展过程。结果表明:随着进口速度的不断提高,各截面上的平均湍动能以及速度的幅值增大,空化发生区域的压力、湍动能以及流场速度变化明显,空化形态具有周期性特征;在4°攻角下水流流经翼型压力面时流场相对稳定,水流流经翼型吸力面时流场相对紊乱;当绕流速度超过15 m/s时,在翼型中后段开始发生空化,其压力以及平均湍动能变化较为明显,同时在非流动方向上产生回射流现象,导致空化流动失稳。该研究对进一步认识水翼空化特性和发展水翼抗空化技术具有指导意义。

In order to analyze the influence of the flow velocity on the unsteady cavitation phenomenon and the evolution mechanism of cavitation process,the three-dimensional numerical simulation of NACA6408 hydrofoil cavitation process was carried out to study the change of pressure,turbulent kinetic energy,velocity and other parameters at different positions of hydrofoil under different flow velocity conditions,then analyze the periodic development of cavitation phenomenon.The numerical results show that with the increasing of inlet velocity,the average turbulent kinetic energy and the amplitude of velocity on each section increase,the pressure,turbulent kinetic energy and flow velocity in the cavitation area change obviously,and the cavitation shape has periodic characteristics.At 4°angle of attack,the flow field is relatively stable when the water flows through the pressure surface of the airfoil,and the flow field is relatively turbulent when the water flows through the suction surface of the airfoil.When the incoming flow velocity exceeds 15 m/s,cavitation begins to occur in the middle and rear section of the airfoil,the pressure and average turbulent kinetic energy change obviously,and the return jet phenomenon occurs in the non-flow direction,leading to the instability of cavitation flow.The study is of great significance for further understanding the cavitation characteristics and developing the anti-cavitation technology of hydrofoil.