基于节流阀模型的变循环发动机风扇准稳态数值研究

为了研究变循环发动机风扇部件在模式转换过程中的气动性能及流场变化规律，在风扇三维数值仿真模型的外涵道出口采用节流阀模型给定出口特征边界，代替模式选择阀门形成了风扇高/低阶混合计算模型，计算过程中通过调节节流阀系数模拟模式选择阀门的开闭过程。在模式选择阀门单独作用时，对风扇部件、中介机匣和分流环在模式转换过程中的气动性能和流场变化进行了准稳态分析，得到了以下结论：在模式转换过程阀门关闭的前半段（阀门开度大于0.4），第二级处于堵塞状态，此时第二级转子槽道正激波位于转子流道内部，并在阀门关闭过程中不断向前移动，第一级在此阶段流场及工作点几乎不发生变化；当第二级转子的槽道正激波被推至叶片前缘附近，第二级退出堵塞后，第一级转子流道内槽道激波开始移动，第一级气动性能才开始发生明显变化；在模式选择阀门从开到闭的过程中，分流环前缘气流攻角增大，内涵道上壁面附面层增厚造成内涵道进口流动出现径向畸变。

Quasi-Steady State Numerical Study of Variable Cycle Engine Fan Based on Throttle Model

In order to study the aerodynamic performance and flow field change law of fan components of variable cycle engine during mode transition, the throttle valve model is used at the outlet of the outer bypass of the fan three-dimensional numerical simulation model to give the outlet characteristic boundary instead of the mode selection valve and to form a fan high / low-order hybrid calculation model. In the calculation process, the opening and closing process of the valve is simulated by adjusting the throttle coefficient . When the mode selection valve acts alone, the changes of aerodynamic performance and flow field of fan components, intermediate casing and split ring during mode transition are analyzed, and the following conclusions are obtained. In the first half of valve closing process(throttle coefficient >0.4), the second stage is blocked. At the same time, the shock wave of the second stage is located in the rotor channel and moves forward continuously during the valve closing process. The flow field and working point of the first stage hardly change during this process. When the channel shock wave of the second stage is pushed near the leading edge of the blade, the second stage exits the blockage state. The channel shock wave in the channel of the first stage rotor begins to move, and the aerodynamic performance of the first stage begins to change significantly. In the process of mode selection valve from opening to closing, the attack angle at the leading edge of the split ring increases, and the wall boundary layer on the upper wall of the inner bypass thickens, resulting in radial distortion of the inlet flow of the inner channel.