Influence of thermodynamic effects on rotor-stator cavity flow in liquid oxygen turbopump

Thermodynamic effects of the cryogenic medium have not been researched adequately for the accurate solution of the turbopump axial thrust, which is a key technique for the reusable rocket engine. In this paper, a liquid oxygen turbopump was chosen to reveal the influence of thermodynamic effects. Experimental tests using liquid nitrogen were carried out to verify the numerical model, and the numerical results under liquid oxygen were discussed to reveal the thermodynamic effects. The results show that the head coefficients and the efficiencies decrease under all operating conditions due to the alterations of the physical properties caused by the thermodynamic effects of the cryogenic medium. The total axial thrusts decrease in the range of 1.63% to 3.22%, and the maximum variations of the axial thrust acting on the impeller shroud and hub are 2.96% and 2.69%, separately, owing to the divergences of the cavity structure. The entropy generation rate was chosen to analyze the power loss, and the minimum deviation caused by the thermodynamic effects is 5.01% at the normal condition; the distributions of the entropy generation rate in the rotor-stator cavities are obviously changed due to the addition of the thermodynamic effects. The new omega method was selected to compare the vortex distribution. The vortex strength changes slightly, owing to the reduction of the medium viscosity caused by the temperature rise. It is critical to consider the thermodynamic effects of cryogenic media for accurately calculating the axial thrust of a high power-density turbopump.