| In this paper effect of structure on a clear water flow field in new water purification device -- Turbid water hydraulic power separation equipment was researched by numerical simulation. Because existing numerical simulation theory is more mature, this is not limited by physical model and experiment condition. The numerical simulation not only saves time and money, but also gives detailed and complete results. So this paper based on the numerical simulation, research the effect of structure on the clear water flow field in equipment.In this paper, RNG k ?εturbulence model was used to simulate flow field of the same size device which had been measured by PIV. The numerical forecasting results agree with the PIV measured results. The simulation has come to the following conclusions:(1)An eccentric centre vortex goes around with the centre of the equipment; the rotation direction is same with the flow direction. Tangential velocity field has the forced vortex characteristics at cylindrical body,vθrn =C,(n<0), forced vortex and free vortex are combined as hybrid eddy at cone. Axial velocity field distributes as two cyclic flows, the direction is upward at the center and side wall, and downward at the other region. Radial velocity distributions are alternate positive and negative, and prove that the clear water flow field in equipment is cylindrical spiral flow field.(2)With the enter flow and bottom diameter of the equipment going up, the velocity will increase. But With height and cone angle increasing, the velocity will decrease. When split ratio of the equipment is same, increasing the scale of the device, the velocity will increase sharply. Setting up underside suspended slab, it helps to reduce the velocity of the flow field. Middle suspended slab reduces the tangential velocity and increases the radial velocity; it also changes the direction of radial velocity. And the effect of underside suspended slab on the flow field is weak.
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