ROTORDYNAMIC MOMENT COEFFICIENTS FOR FINITE-LENGTH TURBULENT SEALS.

Expressions are derived which define dynamic coefficients for high-pressure annular seals typical of wear-ring and interstage seals employed in multi-stage centrifugal pumps. Linear zeroth and first-order perturbation equations are developed by an expansion in the eccentricity ratio. The influence of inlet swirl is accounted for in the development of the circumferential flow. The zeroth-order momentum and continuity equations are solved exactly, while their first-order counterparts are reduced to three ordinary, complex, differential equations in the axial coordinate Z. The results show that the force and moment rotordynamic coefficients are not independent, i. e. , seal misalignment influences the force coefficients, and seal displacement influences the moment coefficients. Numerical results demonstrate both these inter-relationships and the influence of L/D ratios on the moment coefficients.

ROTORDYNAMIC MOMENT COEFFICIENTS FOR FINITE-LENGTH TURBULENT SEALS. Academic Article