| In order to solve the problem of destruction of suspended sediment vortex settling chamber suspended slab system,this paper proposes a scheme for adjusting the radial slope of the suspended slab and arranging the fan annular opening on the suspended slab.In this paper,physical tests and numerical simulations were carried out to study the effects of changes in suspended slab structure on flow field characteristics,sand interception rate,and water consumption rate of suspended sediment vortex settling chamber.The physical experiment is based on the Kashgar first class power plant suspended sediment vortex settling chamber as a prototype.The PIV technology is used to measure the three-dimensional velocity field of the funnel inside the slopes i = 0,0.087,0.173,and 0.259.Based on the test results,the tangential,radial and vertical velocities in the funnel chamber were analyzed in detail.At the same time,the large eddy model and its parameters were verified with the test data.The mathematical model was used to simulate the characteristics of the flow field in the hopper chamber when the suspension was arranged on the annular opening of the fan.Based on the results of numerical simulation of clear water flow field,the particle orbit model(DPM)was used to simulate the sand interception rate and water consumption rate of the vortex settling chamber under different suspended slab.The results show that the radial gradient of the suspended slab changes,the positions of the forced vortex and the free vortex do not change,and the swirl velocity in the forced vortex and the free vortex increases with the radial gradient of the suspended slab increases.The secondary flow intensity of the vertical plane at the radial slope of the suspended slab i = 0.173 is greater than that at other slopes.At 0.55< r/R < 0.65,the radial gradient of the suspended slab i = 0.259,the three-dimensional vertical upward flow velocity is the least,and the vertical upward velocity of i = 0.087 is greater than i = 0.173.With the increase of the radial slope of the suspended slab,the water consumption rate of sand discharge decreases;the radial gradient of the suspended slab i = 0.173 is large for the the sand cutting rate at the sedimentparticle sizes from 0.001 mm to 0.1 mm.Different numbers of fan annular orifices are arranged on the suspended slab,and the positions of the forced vortex and the free vortex are changed;when a small number of fan-shaped annular orifices are arranged on the suspended slab,the range of free vortices and forced vortices is larger than the suspended slab without holes,and the strength of the swirling flow in the free vortices and the forced vortex is favorable to the centrifugal separation of the sediment.The secondary flow intensity on the base slope is stronger than the suspended slab without holes,and a large vertical upward velocity appears at the opening of the suspended slab;the water consumption rate for sand discharge is increased by 2 % compared with the suspended slab without holes.When sand particle size d = 0.1 mm,the sand interception rate of the funnel is smaller than the suspended slab without holes,and the sand interception rate of other particle sizes is larger than the suspended slab without holes.After the number of orifices increases,the free vortices and forced vortices have smaller ranges than the suspended slab without holes,which slows down the swirl strength of the entire vertical surface and is not conducive to the separation of suspended sediments.The secondary flow intensity near the bottom slope of the column wall(0.75 < r/R < 1)is weaker than that of the suspension without holes,and the water consumption rate for sand discharge is 5.4 % larger than that of the suspended slab without holes,and the sand cutting rate of the sediment particle sizes from 0.001 mm to0.1 mm is smaller than that of the suspended slab without holes. |
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