Experimental Study On The Inlet Velocity Field Of Tangential Inflow Spiral Flow Desilting Device

Reservoir siltation seriously affects the normal operation of its function.It is a resolute method to use pipeline spiral flow for reservoir siltation removal.The flow field near the suction head where the spiral inlet of pipeline contacts with silt is the key factor affecting the effect of sediment discharge.In this paper,the influence of different arrangement of diversion bar on the flow field around the suction head is studied experimentally,and the influence of different diversion angle and height on the velocity field at the inlet of the desilter is discussed,which is the basis for efficient desilting of the desilter.This research has certain practical value.By means of physical model test,the inlet velocity field of the tangential inflow spiral flow sediment discharge device proposed in this paper is experimentally studied.The device uses tangential inflow to generate forced spiral flow.The high-speed spiral flow is generated by the guide strip between the suction head and the silt,which makes the sediment start and enter the spiral pipeline.The distribution of the central tangential swirl velocity and the velocity in the flow passage area of the sludge suction head diversion strip at six different angles(10-60 degrees)and at two different heights(12 mm and 16 mm)were studied experimentally.The main contents and conclusions of this paper are as follows1.Study on the velocity distribution at the entrance of the sediment discharger:The tangential swirl velocity is the highest when the angle of the diversion strip is 60 degrees,while the tangential swirl velocity produced by the arrangement of 15 degrees and 30 degrees is the lowest.There are obvious mainstream migration on the flow surface of the suction head at different angles,but the location and degree of migration are different,and the main distribution of head loss in different angles is also different.The height of diversion strip will affect the distribution of flow velocity to some extent,but it can not improve the flow conditions.2.Vortex intensity research:According to the obtained velocity data,select part of the layout of the vorticity intensity for research.It is found that the vorticity intensity of each arrangement is positively correlated with the flow velocity.The eddy intensity of each measuring point arranged at 60 degrees has obvious advantages,that is,the sediment particles that can start and entrap are the largest,and the best effect of sediment removal is obtained in six layout angles.3.Fitting of velocity function:According to the measured velocity data,the relationship function between velocity and center distance of 60 degree arrangement with the best effect of sediment discharge is fitted,and the simple function is as follows:v/v=2.8015(D/r)-1.406.The fitting precision of the function is higher at the far end of the sediment discharger,and there is a certain gap between the fitting velocity near the center and the measured velocity.