齿墩式内消能工压强和流场特性的试验研究
发布时间：2018-08-08 20:22
【摘要】：内消能工是高水头泄水建筑物中有效的消能方式之一,齿墩式内消能工是一种新型的内消能工,这种消能工的提出是为了解决洞塞消能工过流能力低的不足。本文是山西省自然科学基金项目《齿墩式内消能工水力特性试验研究》的部分内容,在前期对齿墩式消能工初步研究的基础上,本文对齿墩式内消能工的水力特性做了进一步的研究,其体型为在有压管道内均匀布置长度为0.9倍管道直径的齿墩段,通过变化齿墩数量以及面积收缩比制定了10组不同的方案。采用物理模型试验的方法,运用多普勒超声波流速仪、高精度数字压力传感器对不同方案不同流量组别情况下的压强、流速进行了测量。分析得到各方案压强分布的变化规律、流量系数、水头损失系数、消能率以及水平流速分布的变化规律。分析了齿墩数量以及面积收缩比对消能特性的影响,齿墩消能工的消能机理、水平流速分布特性以及齿墩式内消能工的脉动压强特性。主要结论有： 1、在保证一定过流能力的情况下,齿墩式消能工的消能率能达到较高的程度。在流量系数为0.407的情况下,消能率可以达到80%以上,是一种具有发展潜力的内消能工。 2、在试验流量情况下,各方案壁面时均压强系数沿程的变化规律相似,均为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影响较小。 3、通过对压强数据的分析,得到脉动压强沿程分布的变化规律。脉动压强的变化幅度均是在齿墩段处变化最大,且面积收缩比越大脉动压强在齿墩段的变化幅度越小,脉动压强最大点出现在齿墩段后1.0D-1.6D的范围内。压强脉动幅值随着面积收缩比的减小而增大。 4、通过对试验方案最大脉动压强的概率密度分布、偏态系数和峰态系数的分析,得到各方案的分布来基本接近于正态分布。 5、通过对齿墩式内消能工流量系数随雷诺数变化情况的分析,得知过流能力与雷诺数无关。面积收缩比是影响过流能力的主要因素,面积收缩比越小管道过流能力越差。 6、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,各方案突扩水头损失系数的变化规律与理论值比较吻合。 7、通过对齿墩段前后管道内水流水平流速的数据分析,得到典型断面水平流速分布图、水平流速矢量图以及典型深度脉动流速沿程的变化规律。
[Abstract]:The inner energy dissipator is one of the effective energy dissipation methods in the high head drain structure. The toothed pier type inner energy dissipator is a new type of inner energy dissipator, which is put forward to solve the deficiency of the low overcurrent capacity of the cavity-plug energy dissipator. This paper is part of the project of Shanxi Natural Science Foundation, "Experimental study on hydraulic characteristics of inner energy dissipators with tooth piers", on the basis of preliminary research on tooth pier type energy dissipators. In this paper, the hydraulic characteristics of the inner energy dissipators with tooth piers are further studied. The shape of the piers is that the tooth piers with a length of 0.9 times the diameter of the pipe are uniformly arranged in the pressurized pipeline. By changing the number of tooth piers and the area shrinkage ratio, 10 groups of different schemes were developed. The physical model test method is used to measure the pressure and velocity of different schemes and different flow groups by using Doppler ultrasonic velocimeter and high precision digital pressure sensor. The variation law of pressure distribution, flow coefficient, head loss coefficient, energy dissipation rate and horizontal velocity distribution are obtained. The effects of the number of tooth piers and the area shrinkage ratio on the energy dissipation characteristics, the energy dissipation mechanism of the tooth pier dissipators, the horizontal velocity distribution and the pulsating pressure characteristics of the internal energy dissipators of the tooth piers are analyzed. The main conclusions are as follows: 1. Under the condition of certain overcurrent capacity, the energy dissipation rate of the tooth pier type energy dissipator can reach a higher degree. When the flow coefficient is 0.407, the energy dissipation rate can reach more than 80%, and it is a kind of internal energy dissipator with potential development. 2. Under the experimental flow rate, the variation law of the average pressure coefficient along the wall of each scheme is similar. The pressure recovery length is mainly affected by the area shrinkage ratio, which decreases sharply in the inlet section of the tooth pier, reaches the lowest in the tooth pier section, and then recovers gradually, and the pressure recovery length is mainly affected by the area shrinkage ratio. The change of the number of tooth piers has little effect on it. 3. Through the analysis of pressure data, the variation law of pulsating pressure along the course is obtained. The variation range of pulsating pressure is the largest at the tooth pier, and the larger the area shrinkage ratio is, the smaller the fluctuating pressure is in the tooth pier segment, and the maximum pulsating pressure point appears in the range of 1.0D-1.6D behind the tooth pier segment. The amplitude of pressure pulsation increases with the decrease of area contraction ratio. 4. The probability density distribution, skewness coefficient and peak coefficient of the maximum pulsating pressure of the test scheme are analyzed. The distribution of each scheme is close to normal distribution. 5. By analyzing the change of flow coefficient with Reynolds number, it is found that the overcurrent capacity has nothing to do with Reynolds number. The area shrinkage ratio is the main factor affecting the overcurrent capacity, and the smaller the area shrinkage ratio, the worse the flow capacity. 6, the head loss coefficient of the inner energy dissipator increases with the decrease of the area shrinkage ratio. In the case of the same area shrinkage ratio, the head loss coefficient of different tooth piers has little difference. The variation law of loss coefficient of sudden expansion head of each scheme is in good agreement with the theoretical value. 7. By analyzing the data of horizontal flow velocity in the pipeline before and after the tooth pier section, the horizontal velocity distribution map of typical section is obtained. The variation of horizontal velocity vector diagram and typical depth pulsation along the flow path.
【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;TV135.2
本文编号：2172946
[Abstract]:The inner energy dissipator is one of the effective energy dissipation methods in the high head drain structure. The toothed pier type inner energy dissipator is a new type of inner energy dissipator, which is put forward to solve the deficiency of the low overcurrent capacity of the cavity-plug energy dissipator. This paper is part of the project of Shanxi Natural Science Foundation, "Experimental study on hydraulic characteristics of inner energy dissipators with tooth piers", on the basis of preliminary research on tooth pier type energy dissipators. In this paper, the hydraulic characteristics of the inner energy dissipators with tooth piers are further studied. The shape of the piers is that the tooth piers with a length of 0.9 times the diameter of the pipe are uniformly arranged in the pressurized pipeline. By changing the number of tooth piers and the area shrinkage ratio, 10 groups of different schemes were developed. The physical model test method is used to measure the pressure and velocity of different schemes and different flow groups by using Doppler ultrasonic velocimeter and high precision digital pressure sensor. The variation law of pressure distribution, flow coefficient, head loss coefficient, energy dissipation rate and horizontal velocity distribution are obtained. The effects of the number of tooth piers and the area shrinkage ratio on the energy dissipation characteristics, the energy dissipation mechanism of the tooth pier dissipators, the horizontal velocity distribution and the pulsating pressure characteristics of the internal energy dissipators of the tooth piers are analyzed. The main conclusions are as follows: 1. Under the condition of certain overcurrent capacity, the energy dissipation rate of the tooth pier type energy dissipator can reach a higher degree. When the flow coefficient is 0.407, the energy dissipation rate can reach more than 80%, and it is a kind of internal energy dissipator with potential development. 2. Under the experimental flow rate, the variation law of the average pressure coefficient along the wall of each scheme is similar. The pressure recovery length is mainly affected by the area shrinkage ratio, which decreases sharply in the inlet section of the tooth pier, reaches the lowest in the tooth pier section, and then recovers gradually, and the pressure recovery length is mainly affected by the area shrinkage ratio. The change of the number of tooth piers has little effect on it. 3. Through the analysis of pressure data, the variation law of pulsating pressure along the course is obtained. The variation range of pulsating pressure is the largest at the tooth pier, and the larger the area shrinkage ratio is, the smaller the fluctuating pressure is in the tooth pier segment, and the maximum pulsating pressure point appears in the range of 1.0D-1.6D behind the tooth pier segment. The amplitude of pressure pulsation increases with the decrease of area contraction ratio. 4. The probability density distribution, skewness coefficient and peak coefficient of the maximum pulsating pressure of the test scheme are analyzed. The distribution of each scheme is close to normal distribution. 5. By analyzing the change of flow coefficient with Reynolds number, it is found that the overcurrent capacity has nothing to do with Reynolds number. The area shrinkage ratio is the main factor affecting the overcurrent capacity, and the smaller the area shrinkage ratio, the worse the flow capacity. 6, the head loss coefficient of the inner energy dissipator increases with the decrease of the area shrinkage ratio. In the case of the same area shrinkage ratio, the head loss coefficient of different tooth piers has little difference. The variation law of loss coefficient of sudden expansion head of each scheme is in good agreement with the theoretical value. 7. By analyzing the data of horizontal flow velocity in the pipeline before and after the tooth pier section, the horizontal velocity distribution map of typical section is obtained. The variation of horizontal velocity vector diagram and typical depth pulsation along the flow path.
【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;TV135.2
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