| The study of water-air two-phase flow in long-distance free flow tunnel is of great significance to the conveyance capacity and operation safety of water diversion project. Based on the open channel uniform flow theory and construction experience of designers, the traditional design and calculation of conveyance capacity and branch tunnel of air supply is empirical and subjective.The standard k ?εmodel coupled with the Volume of Fluid (VOF) method was established; the method of Wall functions which consider the impact on the walls of rough was used near the wall, and the PLIC method was employed to reconstruct the interface. The model has been applied in the long-distance free flow tunnel.The conveyance capacity of this long-distance free flow tunnel has been discussed, the 3D dynamic water-air two-hpase flow is simulated separately for the water diversion project with one, two and three branch tunnels. The main results are as fllows:1. The validity of the model is verified by the simulation for the water level in the drainage and emptying tunnel of a reservoir, the simulated results are well in agreement with the experimental work.2. The mesh sensitivity analysis is accomplished, considerating the mesh accuracy and calculation efficiency.3. Both the design discharge and the enlarged discharge can flow through the tunnel. When the inlet flow is smaller, the the cross section area is smaller and the pressure is greater, so water can easily flow through the tunnel. Accordingly, the discharge of the small inlet flow reduced.4. The layout of branch tunnel has a large influence on the conveyance capacity: the capacity with 01 branch tunnel increases not obviously, contrarily, it increases obviously in all the water diversion schemes with 02 branch tunnel and the water diversion scheme Three and Four with 03 branch tunnel. By analyzed the conveyance capacity, the air supply and cost of branch tunnels, the optimized water diversion scheme is obtained.
|
PDF Full Text Request