Thermal analysis method for avionic device with abnormal geometry under complex air flow field

To save the weight and volume of the bracket, the avionic devices are sometimes fixed onto the airframe from outside directly in the design of air craft with small dimension, which will always lead to an abnormal geometry of the avionic device's case and rearranging of the circuit board assemblies (CBAs), to achieve the aerodynamics goal. However, the inner environment and the air flow outside the craft, which can affect the temperature distribution over the CBAs prominently, have to be considered during thermal analysis at the same time. This paper recommends and presents a method of avionic device thermal simulation and analysis, which can solve the problems caused by the abnormal geometry of the case and the air flow condition. Thermal model should be amended and verified by physical test, and the thermal design of the device can be improved on the basis of thermal simulation. Appropriate baffle and fixed flow also should be added to simulate the real air flow condition in the case.