Study on the rotation speed control method for Ram Air Turbine system

The Ram Air Turbine System is a commonly used airborne auxiliary power system for emergency situations. Wind power is converted to mechanical energy by turbine. Due to uncontrollability and discontinuity of wind and load, it is very important to prevent the turbine from reaching over generation or over speed. In this paper, the centrifugal pitch angle control method, as the most suitable method for RAT was first selected. Based on the moment equilibrium analysis, the rotation control method is analyzed. By using numerical computing tool, the rotation speed was calculated. Compared with the measurement in wind tunnel test, it can be found that the moment equilibrium model describes the performance of the RAT precisely. According to the sensitivity analysis, it can be found that increasing spring stiffness, spring preload and decreasing the product of inertia of the blade component can increase the stable rotation speed. Additionally, changing the damping coefficient does not affect the stable speed, but makes the rotation speed reach stability more quickly.