三维ALE15翼型空化流动数值模拟

在均相流假设下,考虑流体压力和速度湍流脉动、不可凝结性气体的影响,采用完全空化模型计算空化流场的相变,引入密度函数对RNG k-ε湍流模型的湍流粘性系数进行修正,提出了一种空化流动的数值模型和计算方法。根据试验条件给定的参数,采用提出的数值模型和计算方法,数值模拟了空化数为2.3时ALE15翼型定常空化流动。计算得到的不同剖面速度分布与试验数据吻合较好,验证了该数值模型和计算方法的一致性。不同剖面上,远离翼型表面的速度与主流区速度接近,沿着流动方向,远离翼型表面的速度逐渐减小,这与空泡形成的阻碍有关。空泡尾部出现较大的漩涡区,靠近翼型表面的速度为负值,这与反向射流的作用有关。

Numerical Simulation of Cavitation for 3-D ALE15 Hydrofoil

The phase transformation in cavitation flow field was calculated by the full cavitation model considering the pressure and velocity turbulent fluctuation of the fluid,as well as the influence of noncondensable gas based on the homogeneous flow assumption.The turbulence viscosity coefficient was modified by the density function.A computation model and calculation method was proposed for the steady cavitation.The steady cavitation flow field of ALE15 hydrofoil was numerical simulated for the cavitation numbers of 2.3 by using the computation model and calculation method according to the conditions in the experiment.The calculated velocity distributions on different profiles agreed well with the experiment data,which validated the reliability of this computation model and calculation method.The velocity far away from the hydrofoil section was close to the velocity in the main flow region,and gradually decreased along the flow direction for the reason that the cavity acted as an obstacle.There is a large vortex zone in the cavity rear,and the velocity near the hydrofoil section is negative,both caused by the re-entrant jet.