Experimental Research On Hydraulic Characteristics Of Wall Pressing Flow For Rectangle Sharp-crested Weir

The general rectangle sharp-crested weir, when the water head of weir over comes to a certain height ,the weir flow is the free weir flow .In practical application ,it is found that when the discharge of beginning is small and increased steadily ,the weir flow let out sticking to the weir wall within a certain range of water head ,this is the wall pressing weir flow. This subject carry on a large amount of experimental study in the hydraulic character of the wall pressing weir flow of rectangle thin-wall weir ,and discovers through the test as follows :(1) The water surface curve of wall pressing weir flow differs significantly from that of free flow ,after cross the weir the flow is slightly outwards at the outside sharp-crested of the weir top ,and later let out sticking to the weir wall closely .(2) The water head of wall pressing and the discharge how a steady relation, fitting through mathematics, the discharge formula of the wall pressing weir flow is Q=0.022085bH^1.55965. (3) Compared to the free flow, in the presence of the same weir over water head ,the discharge of the wall pressing weir flow is higher by 20.8%²2.4%than that of the free flow ;in the situation of the same discharge ,the weir over water head of the wall pressing weir flow is lower by 14%¹6% on average than that of the free flow .(4)When the weir over water head of the wall pressing weir flow increases to a certain extent ,the weir flow will take off the wall and form the free flow under the function of mass force ,its critical wall pressing head H_{T L}=4.99cm⁵.05cm .This subject has probed into the inherent relation between the Froude Numbers(Fr), Reynolds Numbers(Re), Weber Numbers(We), Euler Numbers(Eu) and the wall pressing weir flow.