弧形闸门局部开启时闸前漩涡水力特性研究

发布时间：2018-02-28 14:03

本文关键词： 漩涡闸门局开临界淹没水深粒子图像测速技术水力特性　出处：《大连理工大学》2016年博士论文　论文类型：学位论文

【摘要】：前人关于水利工程中漩涡问题的研究主要集中在淹没水深较大且结构不变的电站和泄洪洞等进水口,对于闸门局部开启时闸前漩涡问题研究较少,而闸前漩涡同样会带来很大危害,例如诱发闸门等结构物震动,减小泄流量,引起泄流面空化空蚀等破坏。为了避免或控制闸前漩涡带来的危害,本文采用模型试验和理论分析相结合的方法,对漩涡流场和闸前漩涡的水力特性进行了较系统的研究。主要研究内容和结论如下：(1)本文利用圆桶试验研究了立轴漩涡流场的水力特性,采用粒子图像测速技术(PIV)对立轴漩涡流场进行了详细的测量,得到了漩涡切向流速、径向流速、涡核半径、环量和水面线等分布数据,揭示了漩涡流场各水力参数的变化规律；并通过理论分析和试验数据拟合相结合的方法建立了描述漩涡流场的数学模型,经与前人建立的模型及试验数据对比表明,本文所建立的数学模型精度更高,且形式简单,易于应用。(2)本文以某水闸工程为研究对象,通过不同比尺的模型试验对比,对弧形闸门局部开启时闸前漩涡的形成机理、影响因素、临界淹没水深等水力特性进行了研究。研究表明,闸前漩涡的形成是进水口弗劳德数和来流环量共同作用的结果；其影响因素有闸前水深、闸门开度、进水口弗劳德数和来流环量；闸前漩涡存在上、下两个临界淹没水深,吸气漩涡发生在临界淹没水深上下限之间；在临界淹没水深下限附近,来流环量作用较弱,在临界淹没水深上限附近,来流环量作用明显；闸门开度越大,吸气漩涡越强；进水口弗劳德数越大,漩涡越强。(3)通过理论推导和闸前漩涡对比试验数据分析,研究了粘性力和表面张力对闸前漩涡的作用机理和影响。结果显示,按照重力相似准则设计的模型试验,当行进水流的雷诺数RP≥5.1×104、韦伯数We≥142时,可以忽略粘滞力和表面张力对闸前漩涡的影响。另外通过对本文建立的漩涡数学模型进一步推导,得到了闸前吸气漩涡的上、下限临界淹没水深公式,经与本文及前人的试验数据对比证明,其不仅适用于计算弧形闸门前吸气漩涡的临界淹没水深,同时适用于结构不变的侧部或立轴进水口等情况。(4)为消除闸前危害性较大的吸气漩涡,本文在分析漩涡特性和总结已有消涡措施的基础上,针对闸前漩涡的消除提出了竖向消涡隔栅法。试验研究表明：采用竖向消涡隔栅法消除闸前吸气漩涡时,两对消涡隔栅方案消涡效果好,可满足消涡要求。综上所述,本文对闸前漩涡问题进行了较系统的研究,所得成果可以为更深入地研究闸前漩涡水力特性提供数据基础和理论依据,也为工程设计和运行管理提供参考。
[Abstract]:Previous researches on swirl problems in hydraulic engineering are mainly focused on water intake such as power stations and flood discharge tunnels with large submerged depth and invariable structure, but there is little research on the vortex problem in front of sluice when the gate is locally opened. In order to avoid or control the damage caused by the vortex in front of sluice gate, the vortex in front of sluice will also bring great harm, such as inducing vibration of structure such as gate, reducing discharge rate, causing cavitation erosion of discharge surface and so on, in order to avoid or control the damage caused by vortex in front of sluice. In this paper, the method of combining model test with theoretical analysis is used. The hydraulic characteristics of the vortex flow field and the vortex in front of the sluice are studied systematically. The main contents and conclusions are as follows: 1) in this paper, the hydraulic characteristics of the vertical vortex flow field are studied by using the bucket test. The particle image velocimetry technique (PIV) is used to measure the vertical vortex flow field in detail. The distribution data of tangential velocity, radial velocity, radius of vortex core, annulus and water surface line are obtained, and the variation of hydraulic parameters of swirl flow field is revealed. The mathematical model for describing the vortex flow field is established by combining theoretical analysis with experimental data fitting. The comparison with the previous models and experimental data shows that the mathematical model established in this paper is more accurate and has a simple form. In this paper, taking a sluice project as the research object, through the comparison of model tests with different scale, the formation mechanism and influencing factors of the front vortex in the local opening of the arc gate are discussed. The hydraulic characteristics such as critical submerged water depth are studied. It is shown that the formation of the vortex in front of the sluice is the result of the joint action of the Froude number at the inlet of the gate and the amount of the incoming flow ring, and the influencing factors are the water depth in front of the sluice, the opening degree of the gate, The inlet Froude number and the volume of the incoming flow ring; the existence of the vortex in front of the sluice, the next two critical submerged water depths, the suction vortex occurring between the upper and lower limits of the critical submerged water depth, and the lower limit of the critical submerged water depth, the weaker the effect of the incoming flow ring, the lower limit of the critical submerged water depth and the lower limit of the critical submerged water depth. Near the upper limit of the critical submerged water depth, the effect of the incoming flow ring is obvious; the larger the gate opening, the stronger the suction vortex; the larger the Froude number at the inlet, the stronger the swirl. The mechanism and effect of viscous force and surface tension on the vortex in front of sluice are studied. The results show that when the Reynolds number (RP) of traveling flow is greater than 5.1 脳 10 ~ 4, and the Weber number is greater than 142, the model test designed according to gravity similarity criterion is presented. The influence of viscous force and surface tension on the vortex in front of the sluice can be neglected. In addition, the formula of the upper and lower limit critical submerged water depth of the suction vortex in front of the sluice can be obtained by further deducing the mathematical model of the vortex established in this paper. Compared with the experimental data in this paper and previous years, it is proved that it is not only suitable for calculating the critical submerged water depth of the suction vortex in front of the arc gate. In order to eliminate the suction vortex which is harmful to the front of the sluice, this paper analyzes the characteristics of the vortex and summarizes the existing measures to eliminate the vortex. For eliminating the vortex in front of the sluice, the vertical vortex barrier method is put forward. The experimental study shows that when the suction vortex in front of the gate is eliminated by using the vertical vortex barrier method, the vortex elimination effect of the two elimination grid schemes is good, which can meet the requirements of vortex elimination. In this paper, the problem of vortex in front of sluice is studied systematically. The obtained results can provide data basis and theoretical basis for further study of hydraulic characteristics of vortex in front of sluice, and also provide reference for engineering design and operation management.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TV135.2

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