闸阀内部气固两相流动及磨损研究

发布时间：2018-05-20 12:49

  本文选题：平行双闸板闸阀 + 凹槽结构　； 参考：《浙江大学》2013年博士论文

【摘要】：本课题以稀相气力输送中的平行双闸板闸阀为研究对象,对其内部气固两相流动特性以及磨损状况进行了数值模拟和实验研究。研究成果为平行双闸板闸阀的磨损预测以及优化设计提供了理论支持。 论文首先对气相和颗粒相进行了受力分析,建立了平行双闸板闸阀内部两相流动和颗粒碰撞磨损的数学模型,设计了模型的求解方案,并通过文献中实验结果进行了验证。然后基于该数值模拟方法对平行双闸板闸阀的内部两相流动、颗粒碰撞磨损以及磨损改进设计开展了系统的研究。研究中,根据结构分析,将平行双闸板闸阀结构简化为一种管道凹槽结构；通过对凹槽结构的磨损分析,提出了平行双闸板闸阀关键密封面的磨损预测公式,提出了平行双闸板闸阀的磨损改进设计。最后搭建了管道阀门测试平台,对凹槽结构开展实验研究,验证了改进设计方案的有效性。 课题的主要研究工作如下： 1.闸阀内部稀相气固两相流动及磨损的计算模型。针对两相流动和颗粒碰撞磨损的计算需求,采用欧拉-拉格朗日方法对气相和固体颗粒相进行处理。为了减小计算时间以及计算难度,提出了关于流体可压缩性、颗粒粒径、颗粒碰撞等计算假设。根据提出计算假设,通过对湍流计算方法的对比分析,建立了连续相湍流计算模型；通过分析颗粒的受力状况、流场的湍流脉动对颗粒的作用以及颗粒与壁面之间的相互作用规律等颗粒运动参数,建立了基于随机游走方法的颗粒动力学计算模型；通过对单颗粒磨损模型进行选取,并结合泰勒级数展开技术,建立了颗粒碰撞磨损计算模型。 2.平行双闸板闸阀内部稀相气固两相流动研究。对平行双闸板闸阀内部稀相两相流动及相间作用进行了三维数值模拟研究,分析了不同阀门放置方式以及不同阀门开度下,颗粒对气体相流场的影响,并着重考察了阀门的放置方式(水平放置和竖直放置)对阀门内部颗粒运动轨迹的影响,获得了颗粒对流场的作用规律以及流场作用下不同粒径颗粒运行轨迹的变化规律。 3.平行双闸板闸阀内部颗粒碰撞磨损研究。平行双闸板闸阀主要工作在全开工况下,因此基于结构分析将阀门简化为一个管道凹槽结构,并对简化结构开展颗粒碰撞磨损的三维数值模拟研究。由于双闸板闸阀内部关键密封面处的颗粒碰撞磨损最为严重,在研究中重点关注凹槽后壁面的磨损状况,并且引入了总磨损率对磨损程度进行定量分析。研究首先分析了简化结构放置方式对后壁面磨损分布的影响,指出水平放置状况下后壁面磨损主要集中在下半部分(T面),其磨损程度远远大于竖直放置状况(特别是对于大颗粒)；于是着重考察了水平放置情况下流动和结构参数(固气比、颗粒直径、进口速度、凹槽宽度、凹槽深度和管道直径)的变化对T面总磨损率的影响规律；接着基于数值模拟结果和曲面拟合技术,提出了水平放置的平行双闸板闸阀关键密封面下半部分的总磨损率预测公式,并通过16组正交算例的公式预测结果与数值计算结果的对比分析,验证了磨损预测公式的准确性；最后结合前人提出的单颗粒碰撞的磨损模型对磨损预测公式进行了扩展,增加了其适用范围。 4.基于凹槽结构的阀门磨损改进研究。论文对水平放置的前后壁面存在高度差(前壁面高于后壁面)的凹槽结构开展了两相流动及颗粒碰撞磨损二维数值模拟研究,首先分析高度差对气相流场的影响,然后对比分析了高度差对不同粒径的颗粒分布的作用规律,最后考察了高度差的变化对凹槽下游下表面的磨损速率分布规律以及凹槽结构后壁面最大磨损速率的影响规律。研究结果指出微小的高度差结构能够明显地减小凹槽后壁面的最大磨损速率。根据该结果,提出了凹槽结构上下游管道不等内径(上游管道内径略小于下游管道内径)的平行双闸板闸阀磨损改进设计方案。 5.凹槽结构磨损的实验研究。采用高速摄像、表面形貌测量等实验方法对凹槽结构的磨损进行研究,分析了凹槽内颗粒的分布随高度差的变化规律,并讨论了凹槽后壁面磨损的分布规律以及高度差对凹槽后壁面最大磨损量的影响,实验研究再次表明微小的高度差结构能够极大地改善凹槽后壁面的磨损,论文同时将实验结果与凹槽结构的数值模拟结果进行对比,进一步验证了数值模拟方法的准确性。
[Abstract]:In this paper , the parallel double gate valve gate valve in dilute phase pneumatic conveying is used as the research object , and the numerical simulation and experimental research on the gas - solid two - phase flow characteristics and wear conditions are carried out . The research results provide theoretical support for the wear prediction and optimization design of the parallel double gate valve .

Based on the structural analysis , the parallel double gate gate valve structure is simplified into a pipe groove structure .
Through the analysis of the wear of the groove structure , the wear prediction formula of the key sealing surface of the parallel double gate valve gate valve is put forward , and the wear improving design of the parallel double gate valve is put forward . Finally , the test platform of the pipeline valve is set up , and the experiment research is carried out on the groove structure , and the effectiveness of the improved design scheme is verified .

The main research work of the subject is as follows :

1 . The calculation model of two - phase flow and wear of dilute phase gas in gate valve is presented . In order to reduce the calculation time and the difficulty of calculation , the calculation assumption about compressibility of fluid , particle size , particle collision and so on is put forward .
By analyzing the force state of the particles , the effect of the turbulence pulsation on the particles and the interaction between the particles and the wall surface , a particle dynamics calculation model based on the random walk method is established .
By selecting the single particle wear model and combining the Taylor series expansion technique , a model of particle impact wear calculation is established .

2 . A three - dimensional numerical simulation study on the two - phase flow and the phase effect of the internal dilute phase of a parallel double gate gate valve is carried out . The influence of different valve placement modes and different valve opening degrees on the gas phase flow field is analyzed , and the influence of the placement mode of the valve ( horizontal placement and vertical placement ) on the movement locus of the inner particles of the valve is studied , and the law of action of the particle convection field and the variation law of the running track of different particle size particles under the action of the flow field are obtained .

3 . Parallel double gate valve gate valve internal particle impact wear research . The parallel double gate gate valve is mainly operated under full open condition , so the valve is simplified into a pipe groove structure based on structural analysis , and the three - dimensional numerical simulation study of particle impact wear on the simplified structure is carried out .
Then the influence of the change of flow and structure parameters ( solid - gas ratio , particle diameter , inlet velocity , groove width , groove depth and pipe diameter ) on the total wear rate of T - face was investigated .
Then , based on the numerical simulation results and the surface fitting technology , a formula for predicting the total wear rate of the lower half of the key sealing surface of the parallel double gate valve gate valve is put forward , and the accuracy of the wear prediction formula is verified by the comparison between the formula prediction result of 16 groups and the numerical results .
Finally , the wear model of single particle collision proposed by the former is extended to the wear prediction formula , and the application scope is increased .

In this paper , two - phase flow and particle impact wear two - dimensional numerical simulation research is carried out on the groove structure of the front and rear wall surfaces of the horizontal placement . The influence of the height difference on the gas phase flow field is analyzed . Finally , the effect of height difference on the wear rate distribution law of the lower surface of the groove and the maximum wear rate of the wall surface of the groove structure are analyzed .

5 . Experimental study on the wear of the groove structure . The wear of the groove structure is studied by means of high speed camera , surface topography measurement and so on . The distribution law of the surface wear after the groove and the influence of the height difference on the maximum wear amount of the rear wall surface of the groove are discussed . The experimental study shows that the small height difference structure can greatly improve the wear of the rear wall of the groove , and the experimental results are compared with the numerical simulation results of the groove structure , and the accuracy of the numerical simulation method is further verified .
【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH134

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