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在叶轮机械的非定常跨音流场中,激波会对气动弹性稳定性有很大影响。而激波的形状、数目、位置又与叶栅的一系列几何参数及气动参数密切相关,事先难以规定。为能考虑叶型叶栅的非定常跨音带激波绕流,本文发展了一种有限差分数值解法。其中速度势被分解为定常和非定常小扰动两部分,并用跨音松弛法求解关于非定常扰动速势的空问变系数线性复变量微分方程。 文中给出的一些数值结果表明,对于进出口M数均小于1.0的叶栅非定常跨音流动说来,局部超音区结尾处激波的存在有很大影响。本研究还预测到在高亚音进口M数,低负攻角条件下出现弯曲颤振的可能。
In the unsteady transonic flow field of impeller machinery, the shock wave has a great influence on the aeroelastic stability. The shape, number and location of the shock wave are closely related to a series of geometric parameters and aerodynamic parameters of the cascade, which are difficult to stipulate in advance. In order to consider unsteady transonic labyrinthine shock waves around a blade cascade, a finite difference numerical method is developed. The velocity potential is decomposed into two parts: stationary and unsteady small perturbations, and the translinear relaxation method is used to solve the linear complex variable linear differential equation with respect to the unsteady disturbance. Some numerical results given in this paper show that the existence of shock wave at the end of local ultrasound has a great impact on unsteady transonic flows of cascades with M numbers less than 1.0. This study also predicts the possibility of bending flutter under high subsonic inlet M-numbers and low negative-angle of attack.