动静叶干涉中背压扰动叶栅气动力的降阶模型

现有航空发动机气动力降阶模型的研究主要集中在叶片颤振方向,对动静叶干涉引起叶栅气动力变化的问题没有讨论。其中背压扰动是动静叶干涉影响上游叶栅气动力的重要因素。通过对背压扰动的傅里叶分解,分别计算分解背压扰动所得各谐波引起的叶栅气动力响应,由此建立了基于谐波平衡法的背压扰动叶栅气动力降阶模型。在此基础上,研究了各谐波幅值对气动力降阶模型精度的影响。算例的结果表明:提出的方法能非常好地描述动静叶干涉中背压对上游叶栅气动力的影响;根据幅值大小选择主谐波,可以在不大幅降低气动力降阶模型精度的情况下减少待定参数的个数;利用该方法可准确确定任意时刻动静叶干涉中背压扰动叶栅的气动力。

Reduced - Order Model of Aerodynamic Force of Back - pressure Disturbed Cascade in Stator Rotor Interaction

The researches on aerodynamic reduced order model(ROM) of aero-engine are mainly focused on blades flutter. And the problems of aerodynamic forces of cascades due to stator and rotor interaction are not discussed. The back pressure disturbance is an important factor that affects the aerodynamic force of the upper reaches of the cascade. In this paper, a ROM method is proposed based on Harmonic Balance method to calculate the aerodynamic forces of cascades due to back-pressure perturbation. In this method, the parameters used in describing backpressure is simplified by traveling wave method, the periodic back-pressure is decomposed by FFT, the aerodynamic forces of cascades due to the back-pressure are calculated through the aerodynamic forces of cascades due to the decomposed harmonic waves. The influence of the harmonic amplitude on the accuracy of the aerodynamic ROM is investigated. An example is used to verify the proposed method. The results indicate that the proposed method can well describe the impact of the back pressure on the upstream cascades and choosing proper harmonic waves according to the amplitude of harmonic waves in ROM can reduce calculation effort without a lot precision loss. The aerodynamic force of the cascade under the back pressure disturbance can be determined quickly and accurately.