Performance analysis of avionics devices based on electro-thermal-stress multi-physics coupling under immersion cooling

The present study aims to analyze immersion cooling for the work reliability enhancement of avionics devices based on electro-thermal-stress multi-physics simulation. A comprehensive performance indicator considering the maximum DC IR-drop of the power supply network (PDN), the maximum temperature of the electronic elements and the maximum deformation of the printed circuit board (PCB) assembly is constructed to evaluate the effect of different flow distributor structure styles and Reynolds number (Re) on the work reliability of avionics devices. The results show that the maximum DC IR-drop of 2.0 V PDN was 73.83 mV which was the largest value among 1.5 V, 2.0 V, 3.3 V and 5.0 V PDN. The DC IR-drop of design A, design B and design C was smaller than the supply voltage fluctuation in a real design, this indicates that the flow distributor has no significant effect on enhancing the power delivery capability of PDN. The reflow in the middle part of design C makes the average temperature of PCB assembly lower than that of design A and design B by about 1–3 °C. The flow distributor has a significant effect on the maximum temperature of electronic elements and the pressure drop of avionics devices with Re increase, but not viable to decrease the maximum deformation of PCB assembly for design A and design B. The minimum of comprehensive evaluation function f is 0.038 when Re = 43,000 for design C, this means the comprehensive working reliability of the avionics server module is the best. Due to different flow patterns, the average temperature of PCB assembly for design C was lower which improve the electrical and mechanical properties, thus the value of f for design C was always smaller than that of design A and design B. The method and results herein revealed the advantages and potential limitations of immersion cooling on the working reliability of the avionics devices.