Numerical Simulation of the Flow Field in a Statically and Dynamically Eccentric Annular Seal With Non-Circular Whirl Orbits

The flow field in an annular seal is simulated for synchronous circular whirl orbits with 60Hz whirl frequency and a clearance/radius ratio of 0.0154 using the Fluent CFD code. Fluent’s Moving Reference Frame model (MRF) is used to render the flow quasi-steady by making transformations to a rotating frame. The computed flow fields for velocity, pressure and shear stress measurements are compared with the experimental data of Winslow (1994), Thames (1992) and Cusano (2006). The CFD predictions are found to be in good agreement with the experimental results. The present CFD methodology can be extended to other whirl frequencies and clearances. The dynamic wall pressure distributions in an annular seal for non-circular whirl orbits was obtained using CFD. The simulations were performed using a time dependant solver utilizing Fluent’s Dynamic Mesh model and User Defined Functions (UDFs). The wall pressure distributions obtained from the simulations are compared with data of Cusano (2006). The CFD simulations over predicted the pressure field when compared to experimental results however the general trends in pressure contours are similar. The flow field for varying rotor eccentricities are also studied by performing coordinate transformations and rendering the flow quasi-steady at set eccentricities using Fluent’s MRF model. The computed velocity and pressure fields are compared with the time dependant solution obtained using Fluent’s Dynamic Mesh model and UDFs for the same eccentricity. Good agreement in the velocity fields is obtained however the pressure fields require further investigation.