Properties Study On Submerging Outflows Under Games On Broad Crest Weir

In the projects, outflows under a sluice on broad crest weir and with a backward-facing step are two kinds of usual hydraulic phenomenon it, which correctly analyses the features and the conditions of submerging outflow has not only very important practical significance but higher academic value.First, it analyses the phenomenon of outflow submerged under a sluice on broad crest weir and finds that the methods of distinguishing of submerged outflow and calculation of submerged coefficient for outflows submerged under a sluice on flat bottom weir can not fit for broad crest weir. It gives a distinguishing standard whether the outflow under a sluice on broad crest weir is submerged when a modified coefficient of submerged condition a is adopted and h_t >α·h_c".Then, it analyses the model experimental data of submerged outflow under a sluice of ZhengPukou control sluice and give the modified coefficient of submerged condition a which varies with the number of unlocking sluices n.It is believed that when modified coefficient of submerged conditionαisintroduced, the modified submerged current ratio can replace thesubmerged current ratio , then, according to the submerged coefficient andsubmerged current ratio curve ,calculates the submerged coefficient under sluice on broad crest weirσ_s .when the weir is on the flat bottom ,α= 1.At last, a series of experiment are done and modified coefficient of submerged condition for all kinds of base ridges are given. And it is pointed that the value ofαincreases with the length of backward-facing step increasing , decreases with the slope angle of end of backward-facing step decreasing and decreases with the height of back-ward-facing step.