Real-time estimation of transient heat flux and full-field temperature for transpiration cooling

In order to meet the state estimation requirements of near space vehicles under extreme heat load conditions, a one-dimensional transpiration cooling flow and heat transfer model is established in this study, and a real-time inversion framework of time-varying heat flux and full-field temperature based on extended Kalman filter (EKF) is proposed. The standard Kalman filter (KF) based on the assumption of constant thermophysical properties has excellent performance at low heat loads, while EKF exhibits excellent accuracy and numerical robustness under various types of thermal shocks. In addition, this paper analyzes the influence of filter parameters on the inversion performance, and reveals the mechanism of filter parameter amplification inversion error and time delay and oscillation in the transpiration cooling inverse problem. Finally, based on the convection-diffusion mechanism of transpiration cooling, the sensitivity stratification phenomenon of the influence of flow heat transfer and structural parameters on the inversion performance are studied. It is shown that the thermal signal attenuation caused by the increase of spatial absolute distance is the main physical reason for aggravating the ill-posedness of the inverse problem of transpiration cooling. This study can provide theoretical guidance for real-time monitoring and thermal protection structure design of transpiration cooling system for near space vehicles.