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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 viscous vortex numerical method suitable for the analysis of rotor unsteady flow field is established. In this method, the large-scale vortexes in the flow field are dispersed into a number of tiny vortices. The Navier-Stokes equations in the form of vorticity-velocity are used to simulate the transport of vortex elements. The viscous diffusion effect uses high-precision Particle strength exchange method to calculate, and blade attachment vortex and the new generation of vortex ring volume Weissinger-L lift surface theory to solve; In order to significantly improve the computational efficiency, the induction velocity and gradient calculation also introduced a fast multipole Algorithm (FMM). The numerical examples of multiple rotor flow fields in hovering and pre-flying states are calculated by the above method. The effectiveness of the proposed method is verified by comparing the wake vorticity characteristics with the induced velocity distribution. In addition, the method is also compared with the rotor computational fluid dynamics (CFD) method and the traditional free-wake method. The results show that the viscous vortex method can capture the rotor wake better while taking efficiency into account.