Flight Endurance Enhancement Via Thermal Management System Control Subject To Multiple Limitations
David Sigthorsson, Michael W. Oppenheimer, David Doman
Abstract
Modern aircraft designs face increasing thermal loads from high powered electrical systems such as sensor systems and/or directed energy weapons. Fuel is used for cooling critical systems. Improper management of the fuel �ow may cause the temperature of the fuel at some point in the system to exceed allowable limits, thus limiting �ight endurance. In particular, low temperature limits of sensitive electronics or high power demands may be practically limiting. Previous research is leveraged to arrive at a two tank topology for the thermal management system. A reservoir tank contains the majority of the fuel reserve, while a smaller recirculation tank allows for improved thermal management. The modeling of the system is improved by using spatial discretization of dynamic thermal models to replace steady-state equations. Leveraging experience and analysis, the control design is divided up using time-scale separation and assigning distinct uses for controlled actuators. An operation mode controller dictates single or dual tank mode operation based on an analysis of the steady-state and thermal limitations of the model. A tank level controller regulates the recirculation tank level. Finally, the temperature controller prevents exceeding any thermal limitation. The system is tested in simulation and compared to a baseline controller, demonstrating both performance and robustness.