The open impeller applicable to liquid rocket pumps is a new technology compared to the conventional closed impeller widely used in existing liquid rocket engines. This paper describes the application of three-dimensional and unsteady Reynolds-averaged Navier-Stokes simulations to investigate the detailed flow field in a liquid rocket hydrogen pump with an open impeller. In order to investigate the influence of the compressibility of hydrogen, both compressible and incompressible URANS simulations were performed for comparison with the LE-X hydrogen pump test. First, the computed results were validated relative to the experimental results obtained in the pump test. Second, the detailed flow field was investigated by comparing the compressible and incompressible URANS results. The computed results agreed well with the experimental results, and revealed several key features in the open impeller.
