High Flow Gain Inlet Cover Treatment for Inducer Cavitation Suppression

ABSTRACT: Cavitation which leads to head falloff and feed system instabilities are a constant source of problems for the low net positive suction head (NPSH) pumps that are needed for advanced liquid rocket engines. Head falloff limits the pumps capability to deliver propellant at the required pressure and cavitation induced instabilities are a significant source of structural failures in rocket propulsion systems. The instabilities are particularly pronounced at low flow off design conditions and can cause severe cavitation-induced surge or oscillations in the propellant feed system, leading to mission failure. The high mass flow gain inlet cover in Figure 1 delays cavitation induced head falloff and it eliminates cavitation instabilities at low NPSH conditions for all flow rates, but is particularly effective at low off-design mass flows. The cover pulls the blade tip vapor cavity and vortex away from the blades to delay head falloff and improve flow stability. The high recirculation flow rate or gain through the cover maintains an optimal flow field on the pump inducer inlet for stable operation, even down to near shut-off conditions. BENEFIT: Significantly improve the suction capability, stability, and flow range of rocket turbopumps operating with a wide range of fluids including liquid oxygen, liquid hydrogen, methane, and kerosene. In particular the technology will eliminate the need for boost pumps, reduce turbopump stage count and weight, increase efficiency, increase margins of safety and reliability, and reduce propellant tank weights through lower pressurization requirements. The technology will open up the turbopump/engine/vehicle design trade-off space by moving the pump suction performance constraint and allow for a better optimal total launch system design. The cover treatment can also be used in other commercial industrial applications that require stable high suction performance like LNG transfer pumps, two-phase pumping for electronic component cooling, supercritical CO2 power generation cycles, and boiler feed water pumps.