Large Eddy Simulation Of Flow Around A Strut And Ejection Flow From A Strut Base In Combustor Of Scramjet

One problem of combustion in supersonic flow is the mixing of injected fuel with the core supersonic flow during the short residence time. The strut offers injection into the main flow and improved rapid mixing by increasing large eddy in flow, so it is very important to pay more attention to the study of strut. In this thesis, a two dimensional strut has been studied by Dynamic hybrid RANS(Reynolds-Averaged Navier-Stokes)/LES(Large Eddy Simulation) approach.Dynamic hybrid RANS/LES approach based on Menter'sκ?ωSST model is developed for compressible turbulent flow, using a distance-dependent blending wall function to shift the turbulence closure by SST model near solid surfaces to LES subgrid closure in free shear layer regions. The Localized Dynamicκ-equation Model is employed for LES subgrid model. The Dynamic hybrid methodology is conducted to investigate the supersonic flow over two-dimension back-facing step and fuel jet in supersonic flow. The code adopted in calculation is validated by comparing with the available experimental results and numerical results by Smagorinsky hybrid RANS/LES model. Comparing to constant hybrid RANS/LES methodology, the Dynamic model shows better in capturing coherent structures of flow fields and time-averaged surface pressure distribution. A Dynamic hybrid RANS/LES code running on parallel computer is developed for strut flow and jet flow. Simulation results provide detail information of vortexes evolution process and coherent structure. It is found that density and temperature depends on and also acts on evolution coherent structures intensively.