Rotordynamic forces developed by labyrinth seals

Numerous tasks have been completed in developing measurement and prediction techniques for accurately determining the fluid-structure-interaction forces on labyrinth seal rotors. The best facility has been designed, fabricated, and assembled; the drive mechanism and instrumentation system have been tested. Further, various improvements to the test apparatus have been implemented. Also, the development of two basic computational approaches for predicting seal rotor forces has been successfully completed. These consist of an improved but approximate analytical model and an extensive computer program incorporating the complete Reynolds-averaged Navier-Stokes equations. The latter model solves finite difference equations in predicting the two-dimensional (axisymmetric) compressible flow in a concentric-rotor labyrinth seal cavity. Details of a corresponding incompressible flow prediction are presented and discussed. The final numerical model will allow prediction of the desired three-dimensional, eccentric-rotor flow field and the associated rotordynamic forces.