The Small Opening Of The Lock Chamber Gates Of The High Head Flow Characteristics Test Research

The hydropower resources are abundance in the southwest of China. In the integrated hydropower development, some special technical problems will be met. For example, when we supply the water for life, industry and irrigation at the condition of the reservoir water level is very high, but the gate in small opening discharges small flow.Based on the former studied results, basic theories and test data, the characters of flow from the sluice with the gate in small opening on the condition of high water head have been investigated in this thesis. Based on former studied results about discharge coefficient of flat gate and the flow condition on my test, we can classify the flow condition as follow: First, according to the flow condition in front of the gate, we can define three different types, the unconfined intake, the long confined intake, the shot confined intake. Second, according to the flow condition behind the gate, we can define two types: the free discharging and the submerged discharging. If the flow condition is different, the discharge coefficient will be different too. Distinguishing the flow condition in the gate shaft is good for people to know and adopt the discharge coefficient of the plat gate.There are two main types of gate adopted in the release works, which are flat gate and arc-shaped gate. A gate is set at the exit of the culvert, because of the flow condition of the long confined intake is different from short confined discharge culvert, so we can not use the conventional flow formula of the flat gate to calculate the discharge capability of high water head and small opening gate. Otherwise, when the relative of degree gate is less than 30% and at the condition of the high water head, the discharge water will suffer from the gate slot and the gate root edge affecting, so the flow condition becomes very complexity. We can not use the conventional flow formulas of the flat gate calculate the discharge capability of high water head and little opening gate. Otherwise, when the relative opening of gate is less than 30% at the condition of the high water head, the discharge water will suffer the gate slot effect and the gate root edge effect, so the flow condition will be complexity and becomes a turbulent jet but the ambience of the jet is air. The velocity of the jet is very high and the flow line is parabola. Now, people study the flow condition that behind the gate often bounds to low water head and take noaccount of gate slot, so the calculated outcome is often not accord to the test result. So according the calculated outcome as the design specification is irrationality and it will cause erosion damage and corrode damage. So it is important for us to study the flow character on the condition of high water head and small opening degree.According to the analysis of the test data, correlated data and the waterpower factors about the nappe behind the plat gate, a discharge coefficient formula about the long confined intake of free discharge plat gate and arc gate is deduced. Then I further deduce a contraction depth of water formula about the long confined intake of free discharge plat gate and arc gate. Finally, an empirical formula about the nappe characteristic points behind the plat gate is deduced and the maximal current velocity behind the contraction depth of water is deduced.