湿式混凝土喷浆机喷嘴的优化设计研究

发布时间：2019-04-18 17:41

【摘要】：喷浆机是喷射混凝土支护的重要机具,广泛应用于矿山、公路隧道、涵洞、煤矿井巷和水利水电工程。喷嘴是喷浆机的核心部件,其结构设计是否合理以及结构参数的匹配关系直接影响喷嘴内出口混合均匀程度,进而影响喷嘴施工时的回弹量。然而,现实中喷嘴结构的设计并不合理,导致在施工作业中,依然会出现物料混合不均匀、物料粘结管壁、回弹量大、脉冲现象严重等问题。为解决上述问题,本论文做了如下工作:1.运用多相流基本理论对喷嘴内混合流体建立了数学模型。通过理论计算得到喷嘴出口混合流体的速度值和压力值。分析了喷嘴内砂子、速凝剂、压缩空气、水泥浆各相在喷嘴内部的混合机理,根据流体的流动特性选择了正确的数值模拟方法和湍流模型。2.对喷嘴结构模型进行了简化,在流体前处理软件Gambit中建立了流场分析模型,完成了喷嘴不同区域的网格划分,最后定义了不同的边界类型。3.将划分好的网格导入到Fluent软件对喷嘴内混合流体进行数值模拟,得到了喷嘴内混合流体速度场、压力场、各相体积分数的分布情况。并分析流场分布与喷嘴结构之间的关系,运用数理统计当中的均值和标准差对喷嘴出口混合均匀程度做了定量分析,得到喷嘴内不同截面上成分均匀度和速度均匀度。4.为了提高喷嘴出口混合流体混合效果,完成了喷嘴结构的初步改进。引入正交试验法,对改进后的喷嘴结构参数进行了优化,选取出口成分均匀度和速度均匀度为考核指标,以泥浆管入射角、预混合管长度、变径管长度、聚料管长度为优化参数,设计了16组试验方案,利用Fluent软件对16组不同结构模型进行数值模拟,采用极差分析法对正交实验所得结果进行处理,得到了各个参数对喷嘴混合程度影响的主次顺序以及喷嘴最优结构参数组合,研究结果对喷嘴结构的设计具有一定的指导意义。
[Abstract]:Grouting machine is an important tool for shotcrete support. It is widely used in mines, highway tunnels, culverts, coal mine lanes and water conservancy and hydropower projects. The nozzle is the core component of the spraying machine. The rationality of the structure design and the matching relation of the structural parameters directly affect the mixing uniformity of the nozzle outlet, and then affect the springback amount of the nozzle during the construction. However, the design of nozzle structure is not reasonable in reality, which leads to some problems in construction operation, such as uneven mixing of materials, bonding of materials to pipe wall, large springback, serious pulse phenomenon and so on. In order to solve the above problems, this paper has done the following work: 1. The mathematical model of mixed fluid in nozzle is established by using the basic theory of multiphase flow. The velocity value and pressure value of the mixing fluid at the nozzle outlet are obtained by theoretical calculation. The mixing mechanism of sand, quicksetting agent, compressed air and cement slurry in the nozzle is analyzed. The correct numerical simulation method and turbulence model are selected according to the flow characteristics of the fluid. 2. The nozzle structure model is simplified, the flow field analysis model is established in the fluid pretreatment software Gambit, and the mesh division of different regions of the nozzle is completed. Finally, different boundary types are defined. The meshed mesh was imported into the Fluent software to simulate the mixed fluid in the nozzle, and the velocity field, pressure field and volume fraction distribution of the mixed fluid in the nozzle were obtained. The relationship between flow field distribution and nozzle structure is analyzed. The mixing uniformity degree at nozzle outlet is quantitatively analyzed by means of the mean and standard deviation in mathematical statistics. The uniformity of composition and velocity on different cross sections of nozzle is obtained. 4. In order to improve the mixing effect of mixing fluid at nozzle outlet, the preliminary improvement of nozzle structure was completed. The structure parameters of the improved nozzle were optimized by introducing the orthogonal test method. The uniformity of the outlet composition and the uniformity of the velocity were selected as the examination indexes, the incident angle of the mud pipe, the length of the pre-mixed pipe and the length of the variable diameter pipe were selected as the examination indexes. The length of aggregate tube is the optimized parameter, 16 groups of test schemes are designed, 16 groups of different structural models are numerically simulated by Fluent software, and the results of orthogonal experiment are processed by the method of extreme difference analysis. The primary and secondary order of the influence of each parameter on the mixing degree of the nozzle and the optimal structure parameter combination of the nozzle are obtained. The results of the study have certain guiding significance for the design of the nozzle structure.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU643

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