Rotor Speed And Inlet Swirl Effects On Leakage And Rotor-dynamic Coefficients Of Tapered Annular Gas Seals

摘要

In turbo machines, rotor-fluid interactions induce forces which can cause rotor deflection or vibration. This paper presents the governing equations of a bulk flow model to determine leakage and rotordynamic coefficients of tapered annular gas seals. The bulk flow method is based on two control volume using the Moody's turbulent shear stresses. A perturbation analysis is employed to develop zeroth and first order perturbation equations for small rotor motion about a centred position by an expansion in the eccentricity ratio. These equations are numerically integrated to find leakage and reaction force components. The linear dynamic equation relating reaction force to rotor displacement is introduced to find rotordynamic coefficients without neglecting inertia term. First, the model has been validated on Scharrer and Nelson results, then the dependency of the seal dynamic characteristics on rotor speed and inlet swirl is presented.