【作者】 杨庆；

【导师】 戴光清；

【作者基本信息】 四川大学 ， 水力学及河流动力学， 2002， 硕士

【摘要】 为了进一步深入研究阶梯溢流坝坝面水力特性，同时探求在大单宽流量下提高阶梯溢流坝消能率的措施，本文主要采用物理模型试验和理论分析相结合的方法对阶梯溢流坝坝面水力特性进行了较为系统的研究。 首次采用了激光多普勒测速仪对阶梯溢流坝的典型速度场进行了详细测量，分析了阶梯溢流坝的消能机理。由于阶梯的存在，使得水流在阶梯凹角内产生强烈的水平横轴旋涡，旋滚水流与外部主流之间不断进行的动量交换加剧了水流内部的紊动，从而使阶梯溢流坝有较高的消能率。考虑掺气后的消能率实测计算值与理论计算值吻合较好，这表明掺气的影响是不可忽略的。 通过对阶梯溢流坝的过渡阶梯的起始位置和具体尺寸的试验研究。得出过渡阶梯的最佳起始位置约在坝顶曲线段1／2高度处且相邻阶梯的尺寸相差较大时，所得的消能率较高。在坝趾处，不设反弧段比设反弧段时的消能率高，但坝下水平段的压强值较大。 为了提高在大单宽流量时阶梯溢流坝的消能率，本文提出了掺气分流墩和阶梯相结合的新型消能形式，并对其进行了试验研究。掺气分流墩的增加，明显地改善了阶梯面上的压强分布，消除或减小了阶梯凹角内和立面上部的负压；由于掺气分流墩使水流纵向扩散以及挑流落下后在阶梯上的撞击，使水流的掺气浓度和消能率都得到较大的提高，降低了阶梯面空蚀的可能性，特别是在大单宽流量时，这种效果更为明显。 四川大学硕士学位论文 利用阶梯的消能作用，提出把阶梯作为弯道急流的一种控制措施。即在上级陡坡采用阶梯，在弯道段采用舌压板和导流消能栅的“消一导”结合方式来控制弯道急流，通过模型试验验证，取得了较好的效果。更多还原

【Abstract】 In order to deeply stUdy the characteristics of overflow and seek for themeasure to increase the energy dissipation of the stePped spillway at large edtdischarge, the method of model test and theory analyZe are used to study the stePPedspillway oveffiowThe tyPical velocity field of oveffiow is measured using the Laser DopplerAnemometer and the mechbosm of the energy dissipation is analyzed. The mainreason of the stepped spillway having greater energy dissipation is tha there is bighorizontal vortex in the inner angel of the steps and it makes momenbo exchangewith outer mainstream then accelerates the theulence in the Water. It shows that theaeration influence is not neglect after correcting between the theory value andpractice calculate value.In the paPer the initial Iocation and dimension of step are studied from whichwe get the conclusion tha the energy dissipation is highcr if the initial location is atthe curve section of l/2 height of the sPillway top and the dimension gaP of neighborsteP is bigger, The energy dissipation is higher. At the toe of thc StePPed spillWay ifexchange a series of steps fOr arc section, the highe enersy dissipation can be gotbu the pressure is higher in downstream icction.In order to increase the energy dissipation of stePped spillway at Iarge unitdischarge, the integhty dissipater of Aerated splitter pier and StePpe characteristics isstUdied. Because of verticaJ diffhaion now by aerated splitter and impachng stePpe3by drop flow, the air concentration and the energy dissipation efficiency are greatly increased; the potentiality of cavitations is decrease. In special at large unit discharge, this effect is more obvious.Making use of the energy dissipation function of the step, the measure which takes step as curve jet flow is proposed. Namely, setting a series of steppes in the slope channel and deflector plate and hanged-grid at the cure section, through the model test, the conclusion is very good.更多还原