Study On The Mechanism And Characteristics Of Three-dimensional Wall Jet In Dynamic Water

Pipe line has been used widely for transporting water with the development of economics. In the water pipeline, sediment deposition is a relatively common but difficult problem. Although there are some simple engineering measures to solve this problem, but the main measure is desilting by artificial currently. This will increase the running cost and reduce the running time surely. To solve this problem, a facility using three-dimensional wall jet for dredging work of the pipeline on a regular basis is envisaged to develop. Based on this, the paper researched the mechanism and characteristics of the three-dimensional wall jet in dynamic water. The paper studied the distribution of velocity, the law of development and the sphere of influence through theoretical analysis, model test and numerical simulation. The main research content of this paper are as follows:1. The results of the theory of free jet and the three-dimensional wall jet in hydrostatic water is summarized. Drawing on the methods of their research, the foundation for the research of the hree-dimensional wall jet in dynamic water is laid.2. The distributions of velocity of two different wall jet velocity at a certain speed of hydrostatic water are measured by model test. The distributions of velocity of both symmetry middle plane and level development plane are obtained. They have similarity in each plane. The maximum velocity of symmetry middle plane shows the trend of attenuation with the development of three-dimensional wall jet.3. The flow fields of 3 groups with different dynamic water velocity are calculated by numerical simulation, each group contains 7 differtent jet ratios. There are 21 conditions totally. The computation results are consistent with the model test data. The analysis of the numerical simulation results obtained that the sphere of influence of the three-dimensional wall jet has a linear relationship with the jet ratio, it increases with the increase of the jet ratio. At the same time as the increasing speed of the flowing water, the increase rate of the sphere of influence is gradually increased.The development pattern of three-dimensional wall jet in dynamic water is obtained by the research of this paper. It focused on the impact to sphere of influence of jet ratio and the velocity of dynamic water. The results of the research show that three-dimensional wall jet can improve the velocity of water near the wall greatly, so it is possible to apply to the actual dredging work in the pipeline.