【作者】 曹长冲；

【导师】 刘韩生； 徐根海；

【作者基本信息】 西北农林科技大学 ， 水力学及河流动力学， 2008， 硕士

【摘要】 水利水电工程中,泄水建筑物是保证水库安全,充分发挥工程效益的关键,消能防冲也一直是水利科学鼓励研究的方向。Chardara(卡尔达拉)水电站运行中发现的问题:卡尔达拉水电站泄水道底板现行体型采用的是直线折坡形式,由于该体型设计不合理加之年久失修,底板出现了不同程度的破坏,流态不佳,影响了工程的正常运行。在现行方案的试验长中还发现:首先由于泄水底孔闸室内存在两个孤立的中墩,导致闸室流态较差;其次,泄水道底板直线连接,流线性较差,底板出现了一定程度的损坏;最后,消力墩的尺寸设计的不合理也导致了消力池中水流流态较差。针对卡尔达拉水电站在长期的运行中出现了流态不良,堰顶局部存有负压,泄水道底板发生了不同程度的空蚀破坏。针对上述问题进行了不同方案的试验研究,并从水流流态、底板压强、消能率等方面综合考虑,优化了体型,提出了解决办法。本研究采用物理模型试验,工程的试验研究是依据工程资料,按照重力相似准则,在实验室建立水工整体模型,模型比尺采用1:40,通过模型试验验证并完善泄水道建筑物体型及辅助消能工布置的合理性,研究泄水道水流特性和泄流消能效果,提出了改善泄水道水流流态和提高消能率的工程措施。本研究主要完成以下三方面工作:(1)卡尔达拉水电站泄水道底板体型优化试验。泄水道底板体型在经过现行方案体型Ⅰ,直线折坡型,底板采用1:2.8的斜坡相连;三种曲线抛物线体型。曲线抛物线Ⅰ型:底孔堰面由斜直线改为抛物线方程为y=x~2/84.681;曲线抛物线Ⅱ型:曲线抛物线Ⅰ型的基础上调整堰面曲线,为y=x~2/211.7025堰末端形成6m跌坎;曲线抛物线Ⅲ型:方程y=x~2/423.405将堰面改为抛物线型,堰面末端抬高8m;一种直线跌坎型,在曲线抛物线Ⅱ型的基础上将堰做成平面并将堰面末端抬高至水平,形成10m的跌坎。在经过5种泄水道底板体型的优化试验研究得出,底孔堰面由斜直线改为抛物线,方程为y=x~2/84.681,即为优化方案Ⅰ,亦即实施方案。试验表明该种抛物线型堰面可以消除运行工况下堰顶附近的负压,避免了堰顶附近的空蚀破坏,改善了空化性能。(2)为了解决现行方案中消力墩高度过大的问题,经过了8种体型布置形式的优化比较,体型1:消力墩原位置不变,高度减少至4m;体型2:消力墩原位置不变,高度减少至3m;体型3:取掉上游一个消力墩,下游两个消力墩不变,高度5m;体型4:将上游消力墩移至下游消力墩位置线,并均布,高度4m;体型5:将上游消力墩移至下游消力墩位置线,并均布,并两侧消力墩高度减少至4m;体型6:上游消力墩原位置不变,高度减少至3m,下游改为3个消力墩并均布,并两侧消力墩高度减少至4m;体型7:上游消力墩取消,下游3个且均布,高度减少至3m;体型8:取掉上下游消力墩,在下游消力墩末端下移2m布置4个消力墩且均布,高度减少至4m。经过上述消力墩8种体型布置形式,96个组合试验进行了观测比较,结果表明,现行消力墩布置形式合理可行即:优化方案Ⅰ闸墩+现行方案消力墩布置但墩高应减至4m,各工况水跃位置适中,流态较好,满足工程要求。(3)在经过5种泄水道底板体型及8种消力墩体型优化试验的基础上,进行了不同的优化试验组合,提出的最终实施方案为:优化方案Ⅰ闸墩+堰面体型+现行方案消力墩布置但墩高应减至4m。该方案成功解决了现行方案折坡消力池存在的问题,现已被工程采用。本试验成功地解决了卡尔达拉水电站存在的水工水力学问题。成果已被工程采用。更多还原

【Abstract】 In water conservancy and hydropower project,outlet works are a key for the safety of reservoirs.Energy dissipation problem has been always encouraged to research.During the long-term run of Chardara water power station ,it is found that some hydraulic problems are existing: The configuration of bottom outlet bays is the inflection slope in the present configuration of Chardara water power station. Because the configuration of bottom outlet bays is unreasonable and has not been repaired during the long-term run of Chardara water power station. The damage occurs on floor of bottom outlet bays works in various degrees.The flow pattern is poor.The project security has been influent by above problems. By making hydraulic model test , it is found that some hydraulic problems are existing in the present scheme of Chardara water power station:First, the middle piers are separated,so the flow pattern is poor in the outlet ;Second, the configuration of bottom outlet bays is the inflection slope in the present configuration, the configuration of bottom outlet bays is unreasonable.The damage occurs on floor of bottom outlet bays works in various degrees.The flow pattern is poor.Third, configuration of bottom outlet is unreasonable. The flow pattern is poor.As a result of above problems existence, during the long-term run of Chardara water power station, it is found that the flow pattern is poor, the negative pressure exists near the top of the slope in the outlet bay, the cavitation occurs on floor of bottom outlet works. By thinking about the flow pattern, the pressure ,energy dissipation and so on. The configuration of bottom outlet bays resolves those problems which are existing in the present configuration. The result has been accepted by the project.This study used physical model testing.The pilot project is based on the research project, established in the laboratory hydraulic model,which is designed with similarity criterion of gravity. The model scale is Lr=1:40.The model test verification and improve discharge, body building and supporting the layout of the energy dissipation reasonable, research, water discharge and the discharge of energy dissipation effect. To improve the discharge, flow pattern and increase the rate of energy dissipation measures.This research mainly completes following three aspects of work:(1) The modified configuration of the floor of bottom outlet works of Chardara water power station.The configuration of bottom outlet bays is the inflection slope n the present configurationⅠof Chardara water power station. A 1:2.8 slope connects the inlet and stilling basin; Three curve surfaces has been tested. The curve surface floorⅠ: Changing the straight line slops into curve surface. The curve equation is y=x~2/84.681; The curve surface floorⅡ: The slope curve is modified, the equation of which is y=x~2/211.7025. There is a drop at end of curve floor, which is 6m high; The curve surface floorⅢ: The curve floor is accepted, the equation is y=x~2/423.405, the drop, at end of curve floor, is 8m high. A straight line floor, the drop, at end of straight line floor, is 10m high.The hydraulic model has been tested by making five configurations of bottom outlet bays test. The bringed forward proper configurationⅠof bottom outlet bays ,the equation y = x~2/84.681,is the curve surface floor , is the optimal schemeⅠ,that is the implementation of the scheme.Experiments show that this type of weir parabolic surface can remove the top running condition weir near the negative pressure, improve the properties of space and avoid the weir near the top of the cavitation damage.(2) In order to solve the problem that is the oversized height of baffle blocks in the present scheme, the hydraulic model has been tested by making eight layout forms of baffle blocks test.. Layout 1 of baffle blocks in the present scheme but the hight should be reduced to 4 m; Layout 2 of baffle blocks in the present scheme but the hight should be reduced to 3 m; Layout 3 of baffle blocks in the present scheme Takes upstream one baffle blocks to disappear, downstream two stilling the same baffle blocks ,but the hight should be reduced to 5 m; Layout 4 of baffle blocks, Take the upstream baffle blocks to move to the downstream to the line of position of the downstream baffle blocks, the hight is 4m; Layout 5 of baffle blocks, take the upstream baffle blocks to move to the downstream to the line of position of the downstream baffle blocks, the The both sides baffle blocks hight is 4m; Layout 6 of baffle blocks in the present scheme but the hight should be reduced to 3 m, downstream into three baffle blocks and uniform, and on both sides of stilling baffle blocks hight reduced to 4m; Layout 7of baffle blocks,Take away of the upstream baffle blocks, the three downstream baffle blocks and uniform, hight reduced to 3m; Layout 8of baffle blocks, Takes away the upstream and downstream of baffle blocks, in the downstream baffle blocks under baffle blocks terminal to move to 2m to arrange 4 baffle blocks and uniform, hight reduced to 4m. The hydraulic model has been tested by making eight layout forms of baffle blocks test and 96 rows of observed combination test.The results show that the existing baffle blocks layout forms that is reasonable and feasible: Optimization ofⅠmiddle pier + layout forms of baffle blocks in the present scheme but the hight should be reduced to 4 m, the condition of water jump conveniently located, better flow pattern to meet the engineering requirements.(3) On the basis of optimized scheme test of 5 the configurations of bottom outlet bays and 8 layout forms of baffle blocks,after making different combination of optimization tests.Get the final implementation scheme are: OptimizationⅠmiddle pier + layout forms of baffle blocks in the present scheme but the hight Should be reduced to 4 m. The scheme successful resolution the problem of the inflection slope stilling basin existing in the present scheme slope problems, the result has been used by the project.This test solved hydraulics problem in middle outlet of Chardara water power station.the result has been used by the project.更多还原