Construction and verification of adaptive estimation model of fuel pipeline pressure oriented to flight state coupling

In this paper, an adaptive estimation model of fuel pipeline pressure for flight state coupling is proposed to meet the challenges of multi-physical field coupling and nonlinear dynamic characteristics faced by modern aircraft under complex flight conditions. The model is based on the framework of multi-modal coupled state space model, and integrates dynamic parameters such as flying height, angle of attack and overload coefficient. By coupling fluid mechanics equation and pipeline vibration equation, the interaction between fuel compressibility, viscoelastic effect and mechanical vibration is realized. At the same time, the double time-scale updating mechanism is adopted to quickly respond to the rapidly changing parameters such as temperature and viscosity, and the slowly changing parameters such as pipeline aging parameters are corrected online by Bayesian correction method. In addition, a robust observer based on sliding mode theory is designed to effectively suppress sensor noise and model mismatch error. It is verified by the multi-level joint simulation framework built by MATLAB/Simulink, AMESim and dSPACE SCALEXIO, which covers seven types of standard flight profiles. The results show that the error of 91.6% is less than 4% in 256 steady-state operating points, which meets the accuracy requirements of SAE ARP5008. Under typical maneuvering conditions, the overshoot, adjustment time and root mean square error are significantly better than the traditional methods. In the case of sensor failure, the system can still maintain a certain level of operation, which verifies the high accuracy, strong robustness and good engineering applicability of the model.