CFD Analysis of Viscous Flows in the Sharp Corner of the Grid Fins

The objective of the present study is to verify the flow features including Shock- Shock interactions, Shock-Boundary layer interactions in the sharp corners of the grid fins at free stream Mach numbers 0.8,1.2,1.8,2,2.5, and 3 for the grid fin with chord length 70mm and the gap length 70 mm and thickness 4mm with sharp leading edge and tailing edge. The most important outcome of the 2D studies was idea of classification of different flow regimes encountered in supersonic flow past series plates namely Single body regime, Single Plate regime, Separated Flow regime. These basic flow regimes explain in the Mach 2 flows can be readily extended to higher supersonic flows without any effects. Numerical analysis was also carried out for 3D grid fin single cell with SST turbulence model. First cell height was provided with 5 microns so that maximum Y+ will be less than 1. The different regimes mentioned in the 2D results were also realized in the 3D results. For Mach number 2 and 2.5, The shock -shock boundary layer interactions region was identified and for Mach 3 it was observed that grid fin cell was free from these interactions. Further, Velocity profiles were extracted at different stations along the sharp corner of the grid-fin cell to identify the important flow phenomenon like flow separation, Displacement thickness and Momentum thickness. The boundary layer development and growth along the sharp corner and on the flat surface of the grid fin flow were compared and analyzed. The rate of boundary layer growth and boundary layer thickness were higher along the sharp corner when compared to those on flat surface.