高水头闸室闸门小开度水流特性试验研究

【作者】 唐涛；

【导师】 王海军；

【作者基本信息】 昆明理工大学 ， 水利水电工程， 2005， 硕士

【摘要】 我国西南地区蕴藏着丰富的水资源。在水利资源综合开发中,经常遇到在高水头下,向下游提供小流量的生活、工业或灌溉用水的情况,就会遇到高水头闸室闸门小开度运行的一些问题。 本论文在总结前人成果的基础上,从基本理论和试验数据出发,研究了高水头闸室闸门小开度时泄水隧洞的水流特性。根据前人对闸孔流量系数的研究成果和本次研究流量系数时所遇到的闸门前后水流情况,对闸前闸后水流流态进行了分类。根据闸前水流流态,可分为长有压段和短有压段;按照闸后水流流态,又可分为闸孔自由出流和闸孔淹没出流。闸前闸后的水流条件不同,其影响流量的因素也不同。科学地区别闸前闸后水流流态,有利于人们对闸门闸孔处流量系数的认识和工程上对流量系数的合理采用。 在实际已建和在建工程中泄水建筑物所采用的闸门形式主要包括平板闸门和弧型闸门这两种形式。闸前为长有压段隧洞的水流流态不同于具有短有压段隧洞的水流流态,这种泄水隧洞泄流能力计算不能采用闸前具有短有压段的闸门的流量计算公式。另外,高水头闸室闸门开度小于30%,下泄小流量时,对于平板闸门由于水流受闸门槽和闸前垂直收缩的影响,闸后水流流态较为复杂,形成射流周围环境为大气的附壁射流,水流流速高,水舌形态呈抛物线状。由于目前对闸后水流流态的研究没有考虑闸门槽的影响,因此采用现行公式计算高水头闸室闸门小开度时的计算结果与实际相差较大,所以对于这种高水头闸室闸门小开度时的泄水隧洞水流特性的研究,在理论和实际上都有重要的意义。 根据试验数据以及相关资料分析,提出了闸前有长有压段闸后自由出流的平板闸门和弧形闸门的流量系数公式,并对平板闸门闸后水舌的沿程水力要素进行了分析,在此基础上又推导出闸前有长有压段闸后自由出流的平板闸门和弧形闸门闸后收缩水深及其位置的计算公式,最后给出了平板闸门闸后水舌特征点的计算公式,对弧形闸门则从理论上推导出了收缩水深后沿程断面的最大流速理论值。更多还原

【Abstract】 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.更多还原