冲压空气涡轮叶片设计和气动性能数值模拟

冲压空气涡轮（RAT）是飞机应急能源系统的能量提取部件，涡轮叶片设计和气动性能研究是实现风能高效利用的关键。针对某型飞机应急能源系统的功率需求，依据叶素-动量理论设计RAT叶片，采用计算流体力学（CFD）方法以多重旋转坐标系（MRF）模型模拟可变桨距RAT全三维混合流场，研究涡轮输出功率和风能利用系数随来流速度和飞行高度变化特性，分析涡轮叶片上流体压力和流速分布特点。结果表明：RAT输出功率和风能利用系数随来流速度和桨距角而变化，飞行包线内不同飞行高度下RAT具有不同的动力性能；通过调整桨距角可以实现RAT的恒功率输出；整个流场流动状况比较理想，但仍有改进空间。

Blade design and aerodynamic performance numerical simulation on ram air turbine

Ram air turbine (RAT) is a part of the emergency energy system in plane. It can extract energy from airflow through rotating turbine. Design of turbine blade and study on aerodynamic performance are the key for utilizing airflow energy efficiently. Aimed at the power needed by some type of emergency energy system, we designed turbine blade based on the momentum-blade element theory. Then aerodynamic performance of RAT is simulated by using computational fluid dynamics (CFD) method. Besides, the method of multiple rotation frame (MRF) is used to simulate 3D mixed flow field of the RAT where the pitch angle is adjustable. The performances of turbine power and rotor power coefficient are studied varying with airflow velocity and flight altitude. Distribution of pressure and velocity on blade surface are analyzed. The results show that the extracted power and rotor power coefficient of RAT vary with airflow velocity and pitch angle. RAT has different dynamic performance at different flight altitudes in the flight envelope. Constant power could be obtained by adjusting the pitch angle of RAT. Besides, flow state of the whole field is ideal, but there is still room to improve.