Experimental study on the internal temperature rise of a high-speed canned motor pump for liquid rocket engines

Abstract

High-speed electric pumps are now gradually applied in liquid rocket engines. Compared with the pumps with dynamic seals, the canned motor pumps are more reliable, and thus suitable for delivering risky propellants. However, the partial flow diverted to the air-gap for cooling and lubrication faces the risk of overheating caused by its friction against the rotor. This paper performed an experiment on this issue with a high-speed canned motor pump for a notional rocket engine. Impellers with and without balance holes, as well as different configurations of jet holes, were adopted and their effects were analysed. Results showed that the internal temperature rise decreased by up to 78% when the balance holes were removed, and decreased by up to 40% when the jet hole configuration was modified. Both factors influenced the internal temperature rise by varying the flow rate of the cooling recirculation. The study suggested that the high-speed canned motor pump should be designed with an appropriate flow rate of the cooling recirculation, so as to control the temperature rise of the propellant and ensure safe operation of the rocket engine.