Control of a Switched Mode Fuel Thermal Management System

A novel flexible fuel thermal management architecture with a switched mode control strategy is proposed that provides a framework for increasing the thermal endurance of aircraft that use fuel as a heat sink. Multiple flow topologies within this architecture can be realized by using two valves to provide a range of fuel recycling configurations. The flexible thermal management system uses multiple modes of operation to achieve the goal of extending thermal endurance by switching between modes to achieve the best available configuration given the current operating condition. Dynamic inversion-based controllers are developed for each mode and are used to regulate the temperature at the hottest point in the system to a desired value. A high-level supervisory controller switches among four separate feedback control laws and manages the available flow paths within a fixed structure of pipes, valves, and tanks. The flexible fuel thermal management architecture and controller are tested over a range of simulated operating conditions. Under these conditions, the supervisory controller chooses a path that stores returning hot fuel to avoid overheating of aircraft systems and releases the hot fuel when excessive heat loads are no longer present. The proposed architecture allows for a large operational envelope.