Heat transfer characteristics of external ventilated path in compact high-voltage motor

This paper investigates the heat transfer characteristics of the external ventilated path of a compact, 6 kV, 4-pole, 2500 kW motor using flow-thermal coordination mechanism. A computational model is set up and validated by experimental test results. A series of simulation is performed. It is found that the deflection angle α and outlet angle β of the fan blades are the key parameters affecting the efficiency of the cooling effect of the fan. Optimal measures are adopted by changing the deflection angle and outlet angle of fan blades. External fan efficiency is improved from 28.80% to 29.96% and outlet flow is increased by 0.08 m3/s by optimizing the deflection angle α and outlet angle β. According to the optimization results of external fan, heat transfer characteristics and temperature distribution of the cooler is obtained by the fluid and temperature coupling field. The cooler is optimized by adjusting the height of the windshield, increasing the number of the windshield, changing the shape of inclined plate. It is found that the temperature of hyperthermal fluid of inner ventilated path is decreased from 75 °C to 53.7 °C; at the same time the temperature of cryogenic fluid of external ventilated path is increased from 23 °C to 49.4 °C. The outlet temperature of internal fluid of post-optimized cooler is dropped by 3 °C, and the external fluid temperature is increased by 2.5 °C. The performance of fan and the cooling effect is improved. The results from this study can provide an effective method for structural optimal design of compact high-voltage motors.