Structural design for adaptive heat transfer enhancement

The high heat flux position in a heated device, such as the shell of a scramjet combustor, varies due to different operating conditions. It is hard to control the temperature in this kind of system. This paper examines a method that enhances the heat transfer from a given surface adaptively by using a shape memory alloy (SMA). The SMA is attached to the cooling side walls. It is flat when the temperature is low, but turns into surface roughness in response to high wall temperature. The scheme and operation principle of the adaptive heat transfer enhancement are discussed in this paper. The linear model used to design the controller is built through mini-derivative linearization, based on the mathematical and simulation models of unsteady heat transfer. The analysis shows that the temperature of the hot side walls can be kept around a temperature that the material can bear even though the heat flux change from the scramjet combustion is 2 MW/m².