LARGE EDDY SIMULATION ON VORTEX GRIT CHAMBER FOR SANDSTONE WASTEWATER TREATMENT

The large eddy simulation on high concentration sandstone wastewater in the vortex grit chamber can reveal the transient evolution of a complex flow and is vital to the treatment of wastewater in a hydropower project. An LES-Lagrangian model coupled with VOF method of high concentration sandstone wastewater is established, and the model is gained from the perspective of microscopic interaction between liquid and solid through the molecular kinetic theory. The closure of the subgrid-scale stress model is achieved using the Smagorinsky model and the sliding mesh technique is utilized to achieve the simulation of the cyclone grit tanks blade rotation area. Fine simulation was carried out on the second stage vortex grit chamber for the sandstone wastewater treatment of the pilot test in the southwest. The turbulent flow of liquid and particle were simulated, respectively. Furthermore, Large-eddy simulation and Reynolds turbulence models were compared to show that the large eddy simulation can reveal more sophisticated turbulence phenomenon. Finally the influence of blade rotating speed of the vortex grit chamber was discussed and the optimal rotating speed was 30r/min.