Rotordynamic analysis of circumferentially grooved annular pump seals with turbulent flow and inlet swirl

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Virginia Tech


In this thesis an analysis is developed to predict the leakage and dynamic characteristics for circumferentially grooved turbulent annular seals used in turbopumps. The flow in the groove is modelled using turbulent shear layer theory and an entrance loss model is applied at the inlet and land regions of the seal. The governing equations are derived using Hirs’ turbulent lubrication theory. The equations are expanded to yield zeroth and first order perturbation equations for small rotor displacements about a centered position. The leakage and velocity distribution is obtained from a numerical solution of the zeroth order equations. The first order equations define the dynamic pressure distribution which is integrated to yield the fluid force reactions. The model predictions are compared to test results for smooth walled and grooved seals. The model shows good qualitative agreement with experimental test results for seal leakage and rotordynamic coefficients. Actual quantitative agreement is unresolved given the high level of experimental uncertainty in the test results.