基于Fluent软件的大口径蝶阀流场研究

发布时间：2019-04-20 12:28

【摘要】：蝶阀作为大型管道系统广泛使用的一种控制设备,它的控制可靠性、安全性、制造和运行成本、高寿命对于国民经济具有重要意义。传统的蝶阀设计方法主要依据半经验公式与工程设计手册、图表等,其中的各种经验常数、修正系数都是通过大量实验获取的,这往往需要大量的实验数据,不仅投入高、周期长,而且加大了设计制造成本。本文旨在应用计算流体力学方法为蝶阀设计提供一种新的途径,通过数值模拟不但可以获得产品设计所需的流动特性参数,而且还可以掌握流场内部的详细情况,如压强分布、流速分布、流动分离状态、空化现象发生部位以及非稳态过程中各参数的变化,同时使得应用数值模拟的方法进行蝶阀流阻系数计算和动水力矩计算成为可能,从而有效的指导蝶阀的优化设计。论文的主要内容包括： (1)简述了阀门研究的现状与发展,蝶阀的发展概况、应用领域及其重要意义,介绍了蝶阀的基本特性,指出了当前蝶阀的主要设计方法和存在的主要问题,进而导出了本课题的研究背景、研究意义和研究方法,同时阐述了数值模拟相关理论。 (2)对蝶阀流动特性进行三维数值模拟与分析,计算蝶阀的流量系数和水力转矩系数,通过与实验数据进行比较,验证所建计算模型进行蝶阀流场数值模拟计算的适用性；分析蝶阀在多个开度下的流场结构,对各个开度下的压强、流速和流线进行分析。 (3)对蝶阀在特定工作环境下进行数值模拟与分析,计算蝶阀在多个开度下的流阻系数；计算蝶阀在多个开度下的动水力矩,并与理论计算结果进行了比较分析,得出最大动水力矩时蝶阀的开度范围；比较常流量下和变流量下的蝶阀空化系数,分析容易产生空化的原因,提出了避免空化的观点。 (4)对蝶阀空化现象进行数值模拟与分析,结合工程实际,研究不同入口压强和不同管道结构对蝶阀空化流场的影响,进而提出几种减小空化的具体方法。 (5)对蝶阀流动特性进行非稳态数值模拟与分析,获得蝶阀在不同启闭时间内的流量变化情况和阀盘所受阻力系数、升力系数、动水力矩系数的变化情况,同时分析蝶阀内部流场分布状态,分析空化现象,得出对工程设计与运行管理有益的结论和建议。
[Abstract]:Butterfly valve is widely used as a kind of control equipment in large-scale pipeline system. Its control reliability, safety, manufacturing and operation cost, and long life are of great significance to the national economy. Traditional butterfly valve design methods are mainly based on semi-empirical formulas, engineering design manuals, charts and so on, in which all kinds of empirical constants and correction factors are obtained through a large number of experiments, which often require a large number of experimental data, not only high input, The cycle is long and the cost of design and manufacture is increased. The aim of this paper is to provide a new way for butterfly valve design by using computational fluid dynamics method. Through numerical simulation, not only the flow characteristic parameters required for product design can be obtained, but also the details of the flow field, such as pressure distribution, can be obtained. The velocity distribution, the flow separation state, the location of cavitation and the variation of the parameters during the unsteady state make it possible to use the numerical simulation method to calculate the flow resistance coefficient and the dynamic water moment of the butterfly valve, and it is possible to use the numerical simulation method to calculate the flow resistance coefficient and the dynamic water moment. Thus effectively guide the butterfly valve optimization design. The main contents of this paper are as follows: (1) the present situation and development of valve research, the general situation of butterfly valve development, the application field and its important significance are briefly introduced, and the basic characteristics of butterfly valve are introduced. The main design methods and existing problems of butterfly valve are pointed out, and then the research background, significance and research method of this subject are derived. At the same time, the related theory of numerical simulation is expounded. (2) carry on three-dimensional numerical simulation and analysis to the butterfly valve flow characteristic, calculate the flow coefficient and the hydraulic torque coefficient of the butterfly valve, through the comparison with the experiment data, verify the applicability of the calculation model for the butterfly valve flow field numerical simulation; The flow field structure of butterfly valve under multiple openings is analyzed, and the pressure, velocity and streamline of each opening are analyzed. (3) numerical simulation and analysis of butterfly valve under specific working conditions are carried out, and the flow resistance coefficient of butterfly valve under multiple opening conditions is calculated. The dynamic water moment of butterfly valve under multiple openings is calculated and compared with the theoretical results, and the opening range of butterfly valve is obtained when the maximum dynamic water moment is obtained. By comparing the cavitation coefficient of butterfly valve under constant flow rate and variable flow rate, the reasons for easy cavitation are analyzed, and the viewpoint of avoiding cavitation is put forward. (4) numerical simulation and analysis of butterfly valve cavitation are carried out. Combined with engineering practice, the influence of different inlet pressure and different pipeline structure on the cavitation flow field of butterfly valve is studied, and then several concrete methods to reduce cavitation are put forward. (5) the unsteady numerical simulation and analysis of the flow characteristics of butterfly valve are carried out, and the variation of flow rate of butterfly valve in different opening and closing time and the resistance coefficient, lift coefficient and dynamic water moment coefficient of valve disc are obtained. At the same time, the distribution of flow field in butterfly valve is analyzed, and the cavitation phenomenon is analyzed. Some useful conclusions and suggestions for engineering design and operation management are drawn.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH134

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