Simulation Study On The Fourth Corner And Constraction Of Water Tunnel

Water tunnel is an important equipment for hydrodynamic research.The corner and the contraction are important components of the water tunnel.In this paper,the fluid dynamic simulation software is used to optimize the structure of the fourth corner section and the contraction,in order to provide a theoretical basis for improving the flow field uniformity and reducing the flow pressure loss in the water tunnel.The flow field in the corner is complicated,and there are problems such as flow unevenness and flow separation near the wall surface.The main purpose of this paper is to systematically study the influence of the number of vanes,the distribution method and thickness on the flow field quality of the water tunnel corner.Based on the simulation results,the mathematical relationship of the number of vanes should be satisfied under the optimal state of the flow field at the exit of the water tunnel.The study on the thickness of the vane shows that when the uniformity of the flow field at the corner exit is optimal,the thickness of the vane is in a "V" shape with the unevenness of the flow velocity at the exit of the corner.That is,as the thickness of the vane increases,the velocity unevenness of the corner exit flow field decreases first and then increases.The flow field uniformity of the vanes arranged at equal intervals is better than the equal momentum arrangement,and there is no significant difference in energy loss caused by the two.Due to the impact of shrinkage,the contraction is prone to flow separation at the outlet of the contraction,which destroys the uniformity of the flow field and increases the energy loss.In this paper,the length of the contraction of the square inlet and outlet sections and the contraction curve are simulated.The results show that when the ratio of the length of the contraction to the side length of the inlet section is about 1.7?1.8,it is the critical length to avoid the flow separation of the fluid at the outlet of the contraction.In this paper,we found that the contraction adopts the fifth power curve,the exit velocity unevenness of it is reduced by 3% compared with the mean value,and the boundary layer thickness is reduced by 10% compared with the mean value.For the study of extended contraction,it is important to improve the uniformity of the flow field and reduce the thickness of the boundary layer.