INSTANTANEOUS SQUEEZE-FILM FORCE BETWEEN A HEAT-EXCHANGER TUBE AND A SUPPORT PLATE FOR ARBITRARY TUBE MOTION

The instantaneous squeeze-film force between a heat exchanger tube and a support plate is studied. Based on a two-dimensional rectangular pl ate model, a short-sleeve squeeze-film model for arbitrary tube motion is developed. The instantaneous squeeze-film force is expressed in no rmal and tangential directions. The normal squeeze-film force consists of four nonlinear terms, the viscous, unsteady inertia, convective in ertia and centripetal inertia terms. Three nonlinear terms, the viscou s, unsteady inertia and Coriolis inertia terms, make up the tangential squeeze-film force. An experimental apparatus was developed in order to evaluate the theoretical models against measurements of a finite le ngth squeeze film. A modified model based on the experimental data is obtained where the viscous terms for both directions are multiplied by the instantaneous Reynolds number. All the inertia terms are multipli ed by constant coefficients. The modified model is in good agreement w ith most experimental cases for unsymmetrical linear motion, approxima te circular motion and elliptical motion. The form of the modified mod el is suitable for predicting instantaneous squeeze-film forces in the simulation of heat exchanger tube vibration. Further work using diffe rent sized components and fluid properties is required in order to fin alize coefficient values. (C) 1995 Academic Press Limited