CFD Investigation of the Flow Dynamics Inside a Spherical Surface Indentation

摘要

This study aims to identify the flow structure inside and around a dimple surface indentation that passively reduces flow separation, and to generate characterization parameters for the effectiveness of the aforementioned flow structure in boundary layer separation control. In this study the surface indentation is cut into a flat plate in a diverging channel that creates an adverse pressure gradient. In the baseline flat plate conditions, the shedding vortices formed by the pressure gradient create an oscillating pressure field in the dimple. This geometry has been chosen to simulate the adverse pressure gradient present in the flow regime found on a turbine blade experiencing flow separation, while at the same time reducing overall computational cost. The flow regimes studied range from ReD of 2500 to 20500 (by varying the dimple size) and at various boundary layer thicknesses ReX from 5000 to 80000 (by changing the dimple flow wise location) based on proximity to the base-line separation point. The points of interest verified and closely monitored are the vortical structures inside the dimple and their down stream effects.