建立了一种适用于旋翼非定常流场特性分析的黏性涡数值方法。在该方法中:流场中的大尺度涡被离散为若干微小的涡元,通过求解涡量-速度形式的Navier-Stokes方程模拟涡元的输运等过程;黏性扩散效应采用高精度的粒子强度交换法进行计算,而桨叶附着涡以及新生涡环量采用了Weissinger-L升力面理论进行求解;为显著提高计算效率,在诱导速度及其梯度的计算中还引入了快速多极子算法(FMM)。应用上述方法,对悬停和前飞状态下的多个旋翼流场算例进行了计算,通过对比旋翼尾迹涡量特征和诱导速度分布等,验证了该方法的有效性。此外,还将本方法与旋翼计算流体力学(CFD)方法及传统的自由尾迹方法进行了比较,结果表明黏性涡方法在兼顾效率的同时,还能够更好地捕捉旋翼尾迹运动。
A new numerical viscous vortex simulation method is developed for unsteady rotor flow fields in which large-scale eddies are divided into small vortex particles.Vortex motion and transport processes are obtained by solving the Navier-Stokes equations represented in the vorticity-velocity form.The viscous diffusion term is calculated by a particle strength exchange method with high precision.The circulation of the blade bound vortex and new vortex particles are calculated by using the Weissinger-L lifting surface theory.To improve computational efficiency significantly, the fast multiple method (FMM) is introduced into the calculation of induced velocity and its gradient.By means of the above method, the rotor wake geometry and downwash of different rotors are investigated in hover and forward flight conditions.The validity of this method in rotor flow analysis is verified by comparing with available experimental data.Furthermore, the viscous vortex method is compared with the computational fluid dynamics(CFD) method and the traditional free wake method respectively.The comparison results indicate that the current method has the advantage of better rotor wake capture over the other methods while maintaining efficiency.
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