CFD comparison to 3D laser anemometer and rotordynamic force measurements for grooved liquid annular seals

A pressure-based computational fluid dynamics (CFD) code is employed to cal culate the flow field and rotordynamic forces in a whirling, groove liquid annular seal. To validate the capabilities of the CFD code for this class o f problems, comparisons of basic fluid dynamic parameters are made to three -dimensional laser Doppler anemometer (LDA) measurements for a spinning, ce ntered grooved seal. Predictions are made using both a standard and low Rey nolds number kappa-epsilon turbulence model. Comparisons show good overall agreement of the axial and radial velocities in the through flow jet, shear layer, and recirculation zone. The tangential swirl velocity is slightly u nder-predicted as the flow passes through the seal. By generating an eccent ric three-dimensional, body fitted mesh of the geometry, a quasi-steady sol ution may be obtained in the whirling reference frame allowing the net reac tion force to be calculated for different whirl frequency ratios, yielding the rotordynamic force coefficients. Comparison are made to the rotordynami c force measurements for a grooved liquid annular seal. The CFD predictions show improved stiffness prediction over traditional multi-control volume, bulk flow methods over a wide range of operating conditions. In cases where the flow conditions at the seal inlet are unknown, a two-dimensional, axis ymmetric CFD analysis may be employed to efficiently calculate these bounda ry conditions by including the upstream region leading to the seal. This ap proach is also demonstrated in this study.