MODELING OF FLUID DYNAMICS OF GAS SEALS

摘要

A simplified engineering model based on the roughness treatment is proposed to handle complex geometries arising in many fluid dynamics problems. To develop the concept, the k-e two-equation turbulence closure, with extended wall functions is adopted. The approach is based on spatial averaging in the plane parallel to the boundary of interest. A main aspect of the model is that the mean momentum transport, resulting from the wall-normal velocity component, is a significant contributing term in the near-boundary shear stress balance. Comparing alternative approaches for estimating the roughness coefficients, using the flow in a damper seal as an example, it is found that the mass flow rate deficit approach can offer insight into the roughness lengths evaluation. The present roughness model helps assess the effect of the seal cavity on the overall flow structures.