齿墩状内消能工的水力特性物理模型试验

发布时间：2018-05-07 06:05

本文选题：齿墩状内消能工 + 水力特性　；参考：《太原理工大学》2014年硕士论文

【摘要】：内消能工具有布置简单、经济实用、消能效率高等优点,并且在水利工程中具有广阔的应用前景及良好的经济效益,对其研究意义重大。本文在前人对齿墩状内消能工初步研究的基础上,采用物理模型试验方法对齿墩状内消能工的水力特性进行了进一步的研究,分析不同布置方案的齿墩状内消能工的过流能力、水头损失、时均和脉动压强分布规律、管道流速分布等。主要讨论齿墩消能工的齿墩数量和面积收缩比对上述特性的影响,通过分析得到的主要结论有： 1.管道过流能力由消能工体型决定,与Re关系不大。面积收缩比是影响过流能力的主要因素,面积收缩比越小,过流面积越小,管道过流能力越差,面积收缩比由0.375增加至0.625时,流量系数由0.35变化为0.8。 2.随着管道中流量的增加,齿墩状消能工的消能率也相应增加。流量相同时,收缩比越小,消能率越高。试验范围内,消能率最大可达到80%左右。 3.齿墩式内消能工在消能段的水头损失系数随着面积收缩比的减小而增大,相同面积收缩比情况下,不同齿墩数的水头损失系数差别不大。 4.各方案壁面时均压强系数沿程总体变化规律相似,都是在齿墩进口段急剧下降,在齿墩段内达到最低,之后逐渐恢复,压强恢复长度主要受面积收缩比的影响,齿墩数量的变化对其也有一定影响。 5.各试验方案中,面积收缩比越小,齿墩段前后存在的回流区范围越大,面积收缩比相同时,齿墩数目越多,其回流区涉及范围越大。 6.各方案脉动压强最大值均出现在齿墩段后1.3D～1.6D范围内,面积收缩比越小,其脉动压强越大,在试验范围内,脉动幅值变化可达到2倍速度水头。 7.各试验方案的消能工脉动压强系数随着面积收缩比的减小而增大,面积收缩比相同的情况下,齿墩数目的增加对脉动压强系数有一定的影响 8.各方案的脉动压强的概率密度分布偏态系数在-0.38-0.3范围内,峰态系数在2.92-4.06之间变化,其分布基本接近于正态分布。
[Abstract]:The inner energy dissipation tools have the advantages of simple layout, economic utility, high energy dissipation efficiency, and have broad application prospects and good economic benefits in water conservancy projects, which is of great significance to its research. In this paper, based on the preliminary study on the internal energy dissipators of the tooth piers, the hydraulic characteristics of the inner dissipators of the tooth piers are further studied by using the physical model test method, and the overcurrent capacity of the inner dissipators with different arrangement schemes is analyzed. Head loss, time average and pulsating pressure distribution, pipeline velocity distribution, etc. This paper mainly discusses the influence of the number of tooth piers and the area shrinkage ratio of tooth dissipators on the above characteristics. The main conclusions are as follows: 1. The pipeline overcurrent capacity is determined by the energy dissipator's shape and has little relation to re. The area shrinkage ratio is the main factor affecting the overcurrent capacity. The smaller the area shrinkage ratio is, the smaller the overcurrent area is, the worse the over-current capacity of the pipeline is. When the area shrinkage ratio increases from 0.375 to 0.625, the flow coefficient changes from 0.35 to 0.8. 2. With the increase of flow rate in pipeline, the energy dissipation rate of toothed pier energy dissipator increases accordingly. At the same flow rate, the smaller the shrinkage ratio, the higher the energy dissipation rate. In the range of test, the maximum energy dissipation rate can reach about 80%. 3. The head loss coefficient of the inner energy dissipator increases with the decrease of the area shrinkage ratio, but the water head loss coefficient of different tooth piers is not different with the same area shrinkage ratio. 4. The variation law of the average pressure coefficient along the course of the wall surface is similar, all of them decrease sharply in the inlet section of the tooth pier, reach the lowest level in the tooth pier section, then recover gradually, and the pressure recovery length is mainly affected by the area shrinkage ratio. The change of the number of tooth piers also has a certain effect on it. 5. In each test scheme, the smaller the area shrinkage ratio is, the larger the range of reflux zone is before and after the tooth pier section. When the area shrinkage ratio is the same, the more the number of tooth piers is, the larger the range of return zone is. 6. The maximum pulsation pressure of each scheme appears in the 1.3D~1.6D range behind the tooth pier. The smaller the area shrinkage ratio, the greater the pulsating pressure. In the range of test, the fluctuation amplitude can reach 2 times the velocity of water head. 7. The pulsating pressure coefficient of energy dissipators increases with the decrease of the area shrinkage ratio. The increase of the number of tooth piers has a certain effect on the pulsating pressure coefficient when the area shrinkage ratio is the same. 8. The bias coefficient of the probability density distribution of the pulsating pressure of each scheme is in the range of -0.38-0.3, and the peak coefficient varies from 2.92-4.06, and its distribution is basically close to the normal distribution.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV653;TV131.61

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