基于数值模拟的齿墩式内消能工体型优化分析

发布时间：2018-01-25 04:10

本文关键词： 齿墩式内消能工消能率水头损失齿墩高度　出处：《太原理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：齿墩式内消能工作为近几年新提出的一种内消能工,与传统的内消能工相比,其保证较大过流能力的同时消能率也得到了一定的保证,是一种很有发展潜力的内消能工,因此开展对这种内消能工的研究意义重大。前期已通过物理模型试验对这种内消能工进行了水力特性分析,研究了齿墩数目以及面积收缩比对其消能特性、压强特性及流速特性的影响,本文在前期工作的基础上,采用紊流数值模拟计算软件Fluent对其进行数值模拟,分析了不同齿墩高度以及不同过流面积的情况下齿墩式内消能工的压力、流速分布、紊动能及其耗散率、水头损失及消能率的变化规律。本文的主要研究内容和结论如下:1.不同体型齿墩式内消能工时均压强在管道中的沿程变化规律类似,总体规律都是在齿墩段上游保持稳定,在布置齿墩的部位急剧减小,而后又逐渐增大,直至恢复稳定。2.各体型齿墩式内消能工的断面流速矢量变化规律基本相同,距离齿墩段上下游较远的管道中流速基本上呈矩形均匀分布,在齿墩段附近,贴近管壁处的流速相对比较小,管道中心轴位置及其上下0.3D的范围内流速最大且基本保持同一流速值。随着面积收缩比的减小,反向流动增强,流速恢复长度增大;面积收缩比保持不变,随着齿墩高度的增加,齿墩段后反向流速的范围基本保持不变,流速恢复区长度随齿墩高度的变化不明显,保持在1.3D左右,流速矢量分布受齿墩高度的影响不大。3.各体型齿墩式内消能工的紊动动能和紊动能耗散率分布规律大体相同,最大值均出现在齿墩段进口位置附近,紊动也最为强烈,流经齿墩段后,随着管段长度的增加,紊动能和紊动能耗散率继续衰减,最后恢复稳定。随着面积收缩比的减小,其紊动能和紊动能耗散率也相应增大;面积收缩比一定,随着齿墩高度的增大紊动程度有略微变化,但波动幅度不大。4.通过试验模拟得出管道中的水头损失主要是由于突缩突扩引起的局部水头损失,当齿墩式内消能工体型确定时,不同流量下的水头损失线近似水平,水头损失系数相差不大,水头损失基本不随流量的变化而变化。随着面积收缩比逐渐减小,局部水头损失系数逐渐增加,消能效果也明显增加。当面积收缩比一定,齿墩高度变化时,局部水头损失系数在3.7到3.8之间波动,消能效果也相差不大。5.齿墩体型一定时,齿墩式内消能工的消能率随着流量的增大而增加;同一流量下,随着面积收缩比的减小,消能率随之增大;面积收缩比相同,齿墩高度变化时,各流量下对应的消能率相差不多,说明齿墩高度对消能率略有影响,但影响不是很大。6.影响齿墩式内消能工水流特性的主要因素是面积收缩比,齿墩高度对其影响很小。
[Abstract]:The internal energy dissipation of tooth piers is a new internal energy dissipator proposed in recent years. Compared with the traditional internal energy dissipators, the internal energy dissipation rate is guaranteed to be larger than that of the traditional internal energy dissipators. It is a potential internal energy dissipator, so it is of great significance to study this kind of internal energy dissipator. The hydraulic characteristics of this kind of inner energy dissipator have been analyzed by physical model test. The effects of the number of tooth piers and the area shrinkage ratio on their energy dissipation characteristics, pressure characteristics and velocity characteristics are studied in this paper, based on the previous work. The turbulent numerical simulation software Fluent is used to simulate it. The pressure and velocity distribution of the inner energy dissipator of the tooth pier are analyzed under the different height of the tooth pier and the different flow area. The main contents and conclusions of this paper are as follows: 1. The variation of internal energy dissipation pressure of different types of tooth piers along the pipeline is similar. The overall rule is to maintain stability in the upper reaches of the tooth piers, decrease sharply in the position where the tooth piers are arranged, and then increase gradually. Until the restoration of stability. 2. The variation law of velocity vector is basically the same. The velocity distribution in the pipeline far from the upper and lower reaches of tooth pier is rectangular and uniform, and it is near the tooth pier. The velocity close to the tube wall is relatively small, and the flow velocity is the largest in the central axis of the pipe and the range of 0.3D above and below 0.3D. The reverse flow increases with the decrease of the area shrinkage ratio. The velocity recovery length increased; The area shrinkage ratio remains unchanged, with the increase of the height of the tooth pier, the range of the reverse flow velocity at the back of the tooth pier is basically unchanged, and the length of the velocity recovery area does not change obviously with the height of the tooth pier, and it is kept at about 1.3D. The distribution of velocity vector is not affected by the height of tooth pier. 3. The distribution law of turbulent kinetic energy and turbulent energy dissipation rate of each type of inner energy dissipator of tooth pier is roughly the same, and the maximum appears near the entrance position of tooth pier. Turbulence is also the most intense, after flowing through the tooth pier, with the increase of the length of the pipe, the turbulent energy and turbulent energy dissipation rate continue to decline, and finally restore stability, with the decrease of area shrinkage ratio. The turbulence energy and the dissipation rate of turbulent energy consumption also increase correspondingly. With the increase of the height of the tooth pier, the turbulence degree changes slightly with the increase of the height of the tooth pier. The water head loss in the pipeline is mainly due to the sudden expansion of the local head loss, when the shape of the inner energy dissipator of the tooth piers is determined. The loss coefficient of water head is similar to that of water head loss line at different flow rate, but the head loss coefficient does not change with the change of flow rate. With the decrease of area shrinkage ratio, the local head loss coefficient increases gradually. The local head loss coefficient fluctuates between 3.7 and 3.8, and the energy dissipation effect is similar. 5. When the area shrinkage ratio is constant and the height of the tooth pier changes, the local head loss coefficient fluctuates between 3.7 and 3.8, and the energy dissipation effect is similar. 5. The energy dissipation rate of the inner energy dissipator increases with the increase of flow rate. At the same flow rate, the energy dissipation rate increases with the decrease of the area shrinkage ratio. When the area shrinkage ratio is the same and the tooth pier height changes, the energy dissipation rate corresponding to each flow rate is not much, which indicates that the tooth pier height has a slight effect on the energy dissipation rate. But the influence is not very big. 6. The main factor affecting the flow characteristics of the inner energy dissipator is the area shrinkage ratio, and the height of the tooth pier has little effect on it.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TV653

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