The Study On Energy Dissipation Effect And Better Placement Method Of Double-layer Suspended Grid In The Stilling Basin

To apply the suspended grid energy dissipater into stilling basin, it is not easy for it to be washed by sediment flow because it hangs in the wall of stilling basin, which can play a role to help with eliminating energy. So it is an new auxiliary energy dissipater with better applicability. Previous studies have been carried out on the suspended grid energy dissipation engineering. The study mainly focuses on the arrangement of the single-layer suspended grid, but the studies of arrangement of the double-layer suspended grid are few. Through the experiment, it is very important to study the effect of double-layer suspended grid energy dissipation.On the basis of the research of suspended grid energy dissipater, the model test is designed by the method of uniform orthogonal design and the model experiment results were analyzed by range analysis method. At the same time, this paper uses RNG k~? turbulent flow model of the fluid dynamics software FLUENT to simulate the double-layer suspended grid plunge basin. Then, the numerical simulation results were processed by Tecplot software and the flow velocity distribution map, pressure distribution map, pressure distribution map of the numerical simulation are analyzed, and the average pressure difference around the suspended grid is analyzed. Through comparing model test results and numerical simulation results, it comes to the conclusion. In the model experiment, when the suspended grid is not arranged, the flow pattern in stilling basin is disordered and the water surface fluctuates violently; When the suspended grid is arranged, the flow pattern in stilling basin is stable, and the water surface is not violent; With the same grid number, the flow pattern is more stable and the water surface fluctuation is smaller if arrange double-layer suspended grid, and the flow pattern is stable under the condition of less grid number. The change of double-layer suspended grid has little effect on stilling basin energy dissipation ratio but have a greater impact on the decline of stilling basin depth. Without considering the unit width discharge, the effect intensity of every factor of double-layer suspended grid on drop deep is interval(the most), pitch(relatively strong), number of gate(the less). In numerical simulation, there is little difference between the calculated values of the maximum water depth in the stilling basin and the model test results and the experimental results. On the condition of uniform orthogonal scheme, changing suspended grid interval, pitch and gate number respectively can conclude that when “m1=0.4?m2=1.2?m3=1.1”, it can get a good effect to eliminate the energy. When “m1=0.4?m2=1.2?m3=1.1”, energy dissipation effect is better and the water surface fluctuation is smaller, which is the same with the model test results. Because the first hanging gate and the lower layer of the upper part of the upper section of the energy dissipation basin are all under large pressure, in the design of the structural stability of the suspended grid, it should not only improve the compressive strength of the apron, but also improve the first root suspended grid and the lower hanging the compressive strength of the gate.