Advancement in space exploration necessitates deep throttling of liquid cryogenic rocket engines. Both lunar and Martian robotic and human exploration require engines that can be deep throttled,can start and restart, have a long life, and require minimal maintenance. An engine that is capable of deep throttling at low thrust levels and is versatile enough to accommodate multiple applications would advance the state of the art and enable NASA to meet space exploration objectives. An advanced partial emission turbo pump design is an enabling technology for developing such low thrust level engines. This will complement the current state-of-the-art full emission pump technology.
A liquid oxygen rocket engine turbo-pump design using a partial emission (Barske) pump, combined with a high suction performance inducer design, has been tested to validate a robust, deep throttling capability in 5 to 15 klb (≈22 to 66.8 kN) thrust-range LOX/LH2 rocket engines. Partial emission impeller wheels have an industry demonstrated capability of deep throttling operation with respectable suction performance. The partial emission pump showed consistently stable low-flow/thrust stability at an efficiency similar to that of a capable full emission pump in this throttle range. The high suction performance inducer performed without appreciable head loss at low flow conditions. This combination shows strong potential to enable deep throttling as well as restarts with a minimal turbo- pump/engine thermal conditioning.