The Anti-vortex film cooling technique is investigated by using large eddy simulation (LES) due to its complex mixture between the mainstream flow, the film cooling flow, and the flow through the anti-vortex holes. A geometry of single row of 30 degree round holes on a flat plate is used as the baseline case. Three different values of velocity ratios (Coolant Jet Velocity/Main Stream Velocity) are studied. Two different positions of the anti-vortex holes are investigated with temperature ratio (main stream temperature / coolant temperature) namely 2. The density ratio is taken in consideration. Use of symmetry boundary condition is avoided to capture three dimensional, unsteady, turbulent nature of the flow. Present simulation is carried out by using FLUENT commercial code. Numerical calculation of film cooling effectiveness is validated with reported experimental results. Results show that the used anti-vortex technique improves the film cooling effectiveness. The numerical boundary layer velocity vectors showed that the anti-vortex holes create reverse vortices against the main vortices that are created by the main hole. These reverse vortices help in keeping the coolant jet flow near the surface. |
