In order to meet the requirement of coal mine flooding emergency rescue, a high power, high head and small volume high-speed wet submersible pump is designed. The high speed rescue pump applies the wet motor and pump integrated structure to achieve the best effect . When high speed rescue pump works, the temperature rise of the motor is high, which may cause the damage of the whole unit if the heat which produced by motor can not be taken away fully. The design of the cooling circuit is critical for the performance of the high speed rescue pump. This paper gives two design methods of the cooling circuit of high speed rescue pump. The design performance parameters: Capacity Q = 200m3/h, Head H = 50m, Rotate speed n = 6000r/min, Power P = 600kW. Two cooling circuits contains the normal and reverse one, which are based on theoretical deduction, numerical simulation and experimental verification. First and foremost, two theoretical models of cooling circuit are established by the theory of convective heat transfer .The heat balance and distribution are calculated by theoretical derivation. Then, both three-dimensional models of the circuit are built by CREO and simulated by ANSYS. The method of flow-heat coupling is used to simulate the whole inner flow field of the high speed rescue pump at different running conditions by considering the transformation of thermal performance parameter of cryogenic fluid caused by temperature change. In the simulation ,the information , such as temperature , flow field, pressure distribution of the whole cooling circuit together with temperature and velocity in the gas gap where temperature changed greatly, the convective heat transfer between fluid and motor ,and the flow rate of the cooling fluid are also gained. The analysis results show that: from the comparison of the pressure distribution of the two cooling forms, under the same inlet and outlet liquid condition ,the minimum and maximum pressure value of the reverse circuit are much higher than the corresponding value ,which means the reverse cooling method is better than the normal method as the aspect of cavitation performance. The temperature rise of reverse cooling circuit with the value 1.5K is smaller than the value of the normal cooling circuit. As the key part of the cooling circuit, the motor gas gap has a significant influence on the performance of the circuit. The velocity and temperature distribution is given to study the law of the flow and thermal field in the gap which can supply an intuitive understanding of the key part. At last, an experiment of a model pump is carried out on the test table validated the reliability of the reverse cooling circuit. It can be also concluded that the cooling circuit can satisfy with mode demand of the working condition of the high speed rescue pump.

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