Improving the operational reliability of aeroengines based on coupled thermodynamics and dynamics stochastic responses

Abstract

The gas path system is a special mechanical system that is the core of thrust generation in aeroengines. Random disturbances, both internal and external, including intake and combustion heat random excitations, can cause the gas path system to vary from its equilibrium state and diverge over time, which will reduce the system stability, and even cross the stability boundary to increase the safe operation risk. The impact of random excitations is not fully taken into account by the usual approach of guaranteeing safe and reliable operation with a larger safety factor, which leads to a limited operating range and makes it difficult to fully utilize the gas path performance. This work establishes a correlation expression between the aerothermodynamics and rotor dynamics characteristics of gas path systems using random torques as transfer parameters, and establishes the dynamics model and energy function through random torques and rotor state parameters. Based on the stochastic responses of generalized momentum and energy function, the stochastic dynamics characteristics and stability of rotors and gas path systems were analyzed, and a random excitation critical strength spectrum is formed to ensure the reliable and safe operation of the engine under multi-source random excitation. The results indicate that random excitations make the system response more unpredictable, which lead to the system transition from a stable to an unstable state, resulting in lower reliability. The effects of random excitations over the whole-time scale can be seen in the energy function. Moreover, the operational reliability is improved while enhancing the gas path performance through the application of stochastic response. The effectiveness of the method and the correctness of the results were verified through compressor working lines under different random excitations. This work studies the stochastic responses and reliability of gas path systems from the perspective of coupling thermodynamics and dynamics, and realizes the application of stochastic stability in improving operational reliability.