LIQUID ROCKET ENGINE INDUCER PUMP DESIGN AND PERFORMANCE EVALUATION

Abstract

Copyright © 2023 by ASME.The inducer is an axial pump that is part of the propellant injection system of Liquid Propellant Rocket Engines (LPRE). It is located at the inlet of the turbopump assembly and is critical for designing high performance LPREs. Its geometric and operational characteristics allow it to operate at low inlet pressures, delaying the appearance of cavitation and allowing the propellant tanks to operate at lower pressures. This allows the tanks to be lighter due to a reduced wall thickness requirement. The inducer also needs to operate harmoniously with the other components of the turbopump, especially with the main impeller which is located just downstream in the system. Therefore, it is important that the flow conditions at the inducer inlet and outlet are known and integrated with the turbopump and tank design. The present work aims to develop a methodology for inducer design based on literature established methods in order to obtain geometry and evaluate the flow conditions in liquid-propelled rocket engine inducer pumps. This work will assess outlet flow and pressure conditions in a way that it is possible to match them with the main impeller inlet. Performance criteria are evaluated in terms of the outlet pressure coefficient, flow coefficient and efficiency focusing exclusively on non-cavitating conditions. Two established analytical methods were implemented, one to provide inducer geometry in terms of system operational requirements and another, from National Aeronautics and Space Administration (NASA), for performance prediction based on geometrical and operational parameters. Further analysis is complemented by simulating the generated geometry in a CFD software. The methods were validated using published experimental data and the performances of the analytical, numerical and experimental results were compared. Results showed that the 3D turbulent CFD simulations provided very good agreement of efficiency. Satisfactory results were obtained for the general trends of characteristic curves over a range of flow rates and the spanwise distribution of key performance parameters near design point. The pressure coefficient was significantly overestimated. The results of the analytical models showed good agreement with simulated CFD results, indicating appropriate calibration of loss coefficients.

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