对转风扇排间干涉效应对下游转子颤振特性影响的数值模拟研究

为了探究对转风扇排间干涉效应对下游转子颤振特性的影响,在多叶排环境下,使用谐波平衡法进行振荡叶片非定常流数值模拟。通过颤振预测的能量法考察两种不同多排模型下叶片表面非定常压力响应和气流做功的差异,探讨了对转结构下上游扰动对下游转子气动弹性稳定性的作用机制。研究结果显示:下游振荡叶排的气动阻尼因上游转子的气动干涉而降低,造成这种颤振特性差异的主要原因除了排间非定常扰动引起时均流场中激波形态的变化,还有上游尾迹传播引发的下游转子进口气流角的周期性波动。

Numerical Simulation Research on Effect of Unsteady Inter-row Interaction on Flutter Characteristics of Downstream Rotor in Counter-rotating Fan

In order to investigate the influence of the inter-row interaction on the flutter characteristics of downstream rotor in a two-stage counter-rotating fan, the harmonic balance method is used to simulate the unsteady flow of the oscillating blades in the multi-row environment. Through the energy method for flutter prediction, the difference of the unsteady pressure response and the aerodynamic work done on the blades is investigated using two different multi-row models. And the influencing mechanism of upstream disturbance on aeroelastic stability of downstream rotors under counter-rotating structure is discussed. The results show that the aerodynamic damping of the downstream rotor decreases due to the aerodynamic interaction. The main reason for the difference of flutter characteristics is not only the change of shock wave state in time-averaged flow field caused by unsteady disturbance between rows, but also the periodic fluctuation of inlet flow angle for downstream rotor caused by the upstream wake propagation.