Assessment of Les Performance in Simulating Complex 3D Flows in Turbo-Machines

AbstractThis paper aims at making an assessment of the performance of the large eddy simulation (LES) method in simulating the complex vortical flow in a Francis hydraulic turbine. Firstly the principle of the LES method is presented. Then, three-dimensional turbulent flow of the Francis turbine under selected condition is simulated using the LES method with the Smagorinsky-Lilly model. In the hydraulic turbine, pressure distribution, vortex structures and other flow information are captured, from which the low pressure area beside the suction side of the blade and vortex structure in the draft tube can be seen clearly. Compared with the results from both experiments and simulations by the Reynolds average Navier-Stokes (RANS) method with the k-E turbulent model, the LES results are proven to be more accurate in predicting the overall performance and interior flow characteristics of Francis hydraulic turbine. This work attempts to apply the LES method to simulate the flow field in the flow passages of the...