Thermal-fluid coupling analysis and thermal optimization of servo motor heat dissipation structure

High power density servo motors operating under heavy loads are prone to heat accumulation within enclosed housings, which deteriorates thermal reliability and limits performance. A thermal-fluid coupling enhancement strategy is adopted by introducing a ventilated lower housing to intensify internal-external convective heat exchange while preserving structural protection of the gear train. Results show that compared with the sealed configuration, the ventilated design significantly reduces peak temperatures by 15.66 K, 34.99 K, and 13.65 K, respectively, at 2.942 N·m. Moreover, altitude dependent simulations reveal a competing mechanism between reduced air density and enhanced temperature difference. Although convective heat transfer is weakened due to the decrease in air density, the relatively high and constant freestream velocity mitigates this effect. As a result, under the present operating conditions, the enhancement in temperature difference outweighs the adverse effect associated with the reduction in air density, resulting in a further decrease in the overall servo temperature with increasing altitude. At 8000 m, additional decreases of 8%, 13%, and 7% are found. These findings provide practical guidance for thermal management and structural design of high power-density servo systems.