Transient behavior of fuzzy PID-controlled transpiration cooling with phase change under dynamic thermal environments

To ensure the adaptability and dependability of transpiration cooling with phase change under complex dynamic thermal environments, this study establishes a closed-loop control model of fuzzy PID-controlled transpiration cooling with phase change, numerically investigates the transient evolution of liquid-gas two-phase transport and heat transfer within porous structure under coupled control, and systematically evaluates the response characteristics of conventional PID and fuzzy PID control strategies under different sampling intervals, target temperatures, feedback positions, and thermal conditions. The results indicate that, compared to PID control, fuzzy PID control demonstrates enhanced capabilities in mitigating temperature overshoot, shortening adjustment time, and alleviating positive and negative feedback misalignment. The behavior of phase change exerts a considerable influence on the response characteristics of closed-loop control system, and better control can be achieved when the target temperature substantially exceeds the phase transition temperature or the feedback position is located in the superheated vapor region. Furthermore, fuzzy PID control exhibits superior adaptability and robustness under all typical and real thermal conditions. This work provides novel insights for optimizing coolant control systems in transpiration cooling under complex thermal environments.