Prediction of leakage and rotordynamic coefficients for the circumferential-groove-pump seal using CFD analysis

The circumferential-groove seal is commonly used in various turbopumps to reduce leakage. The main goal of this paper is to develop the method of three-dimensional CFD analysis for determining leakage and rotordynamic coefficients of the circumferential-groove-pump seal. A relative coordinate system was defined for steady-state simulation to calculate the velocity and pressure distributions of the seal clearance at each rotor whirl speed. Instead of setting the inlet and outlet pressures as the boundary conditions in the three-dimensional CFD analysis, as it is more commonly done, we used the inlet velocity and outlet pressure obtained from a preliminary two-dimensional CFD analysis. For prediction leakage, the presented analysis shows improvement from the bulk-flow model analysis. For the prediction of rotordynamic coefficients of K, k and C, the presented analysis provides results in closer agreement with the experimental values than those of the bulk-flow model analysis at several rotor speeds.