Enabling Pump Technologies for Deep Throttle Ascent/Descent Engine Operation

Methane fueled ascent / descent space engines in the 10,000 to 25,000 lbf thrust class require deep throttle capability, placing unique challenges on the turbopumps. Previous engine throttle-ability studies have required both LOX and fuel turbopumps to operate at ratios of volumetric flow rate to shaft speed (Q/N) of 0.2 to over 1 for 10:1 engine throttle operation. Such operational ranges are particularly difficult for pump axial inducers and vaned radial diffusers. Both are prone to fluid separation and stall at low Q/N operation and excessive passage blockage due to cavitation at high Q/N values. The proposed innovation combines two separate technologies to address the inherent design shortcomings of the inducer and diffuser under operation at both low and high Q/N extremes.

The proposed innovation has application in any pump fed rocket engine requiring throttle operation. Of particular interest would be the potential ability for variable speed inducer to eliminate the need for boost pumps on cryogenic rocket engines. Nuclear Thermal Propulsion applications, conventional upper stage liquid rocket engines, and liquid booster class engines could all benefit from this technology. Cryogenic fluid transfer pumps especially those envisioned for on-orbit propellant depots where propellants may be near saturation conditions could benefit greatly from this innovation by enabling improved pump efficiency.

Industrial applications for this innovation are wide ranging. The emerging energy market for liquid natural gas (LNG) stands to benefit from this technology. Specifically, the boost and transfer pumps required for LNG utilization in trains and other heavy equipment propulsion systems often require inducers to ensure that as much LNG can be extracted from mobile storage tanks as possible. This innovation can aid in reducing the amount of heel left in these storage tanks by decreasing the inducer NPSH required for safe operation and long life. The ability to transfer LNG efficiently is receiving increasing importance due to the significant operational cost advantages over traditional gasoline and diesel systems. Barber-Nichols Inc. currently does substantial business in the manufacture of cryogenic pumps for applied research, industrial gas products, and energy production. This innovation could be incorporated into any of these pumps to increase inducer performance, reliability and life.

This is early/mid-stage (TRL 4) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

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