Rotational Speed Stability of Ram Air Turbine Under Aerodynamic Loads.

The Ram Air Turbine (RAT), an emergency device installed within the aircraft, is designed to supply essential power after the failure of all other power systems. However, the design and development of RAT face significant dynamic challenges, particularly the instability of turbine speed in high wind speed environments. Assuming constant blade design parameters and fixed operating conditions with unchanged aerodynamic loads, a stability study of the centrifugal speed governing mechanism within the RAT is conducted. First, a dynamic model of the RAT is established, and numerical simulations are carried out to examine the variations in turbine speed and blade pitch angle. Subsequently, the process of the speed governing mechanism transitioning from an equilibrium state to being disturbed by load fluctuations is linearly approximated, enabling its control system to be modeled, and the aerodynamic load characteristics based on the speed regulation principle are integrated. Additionally, a stability criterion for speed is proposed using the Routh–Hurwitz criterion. Various factors affecting the stability of the speed regulation system are explored based on the dynamic and control models. By analyzing the stability domain of the RAT under different parameters, the influence of speed regulation system parameters on speed stability is assessed, revealing underlying principles and patterns. The results demonstrate that optimizing the design parameters of damping, springs, and centrifugal components in the mechanism significantly enhances the stability of the RAT speed governing mechanism, improving its adaptability to external aerodynamic load characteristics. [ABSTRACT FROM AUTHOR]