Numerical Simulation on Aerodynamic Performance of Ram Air Turbine Based on Mixed Flow Field

Ram air turbine (RAT) is an emergency power source to supply power in case of the main engine and auxiliary engine lost power. Which can extract energy from airflow through rotating turbine. So it is important to investigate turbine aerodynamic performances. According to some type of RAT, we established a numerical model based on Navier–Stokes equation in rotating frames of reference. Calculation domain is divided into three fluid domains. All three regions are linked in the form of interface. Aerodynamic performance of RAT is simulated with computational fluid dynamics (CFD) soft. The extracted power and rotor power coefficient are analyzed under different running conditions. Next, we also investigate RAT aerodynamic performance at different pitch angle and turbine speed. The pressure and velocity distribution on the blade surface are studied. Besides, the method of multiple rotation frame (MRF) is used to simulate mixed flow field of the RAT which pitch angle is adjustable. The simulation results show that: turbine output power and rotor power coefficient can meet the needs of aircraft by adjusting the pitch angle under various operation conditions. The optimal operating point could be obtained by calculating RAT aerodynamic performance. The distribution of blade surface pressure and velocity could provide an important reference for the optimization of turbine blade designing. MRF can be used to calculate turbine aerodynamic performance.