Active thermal control for hypersonic vehicles

The authors present the design and evaluation of a thermal control system that provides cooling by controlling the fuel flow through a network of heat exchangers. The heat exchangers provide cooling for both airframe and propulsion components. It is shown that efficient use of fuel cooling throughout the vehicle's operating envelope requires modulation of the flow splits within the network. Modulating valves are adjusted in-flight to provide optimal distribution of the coolant. It is also shown that this modulation cannot be accomplished through scheduling alone if off-nominal heat loads are to be tolerated. Local control of panel temperature provides some tolerance, but it is not sufficient. A hierarchical controller consisting of a central control algorithm to coordinate the local controllers as well as the turbomachinery control provides increased tolerance to off-nominal heat loads as well as efficient use of coolant.<
>