【作者】 孙章虎；

【导师】 刘在伦；

【作者基本信息】 兰州理工大学 ， 流体机械及工程， 2006， 硕士

【摘要】 在泵的应用过程中,轴向力的大小是影响泵运行稳定性和使用寿命的重要因素之一。从大量的文献资料中不难发现,现有的轴向力平衡装置的应用范围和平衡能力都受到一定程度的限制,而且轴向力计算公式方面的研究也一直是泵设计中的薄弱环节。本文跟踪水泵行业这一难点和热点问题,提出了一种新型轴向力平衡装置,并对新型轴向力平衡装置平衡离心泵轴向力进行理论研究,应用Fluent软件对新型轴向力平衡装置轴向间隙的内部流场进行数值计算,分析轴向间隙内部流场的压力分布规律,为轴向力的计算提供理论依据。 本文的研究内容包括: 通过阐述研究离心泵轴向力的重要意义,分析了传统的轴向力平衡方法,跟踪轴向力研究的最新进展,提出了一种新型的轴向力平衡装置。 首先,介绍了新型轴向力平衡装置的工作原理,分析了新型轴向力平衡装置间隙的内部流动,假设间隙内部流动为层流流动,建立了径向间隙和轴向间隙内部流动的数学模型,并应用粘性不可压缩流体的纳维—斯托克斯方程、连续性方程以及水泵的基本方程式,推导出平衡装置间隙内部的理论压力分布及泄漏量的数学表达式,为轴向力的计算提供理论依据。 其次,用GAMBIT软件建立了新型轴向力平衡装置轴向间隙的计算模型;并应用Fluent软件对不同网格数模型进行计算,得到各自的压力分布云图和截面上的径向速度矢量分布图,分析网格数对数值计算的影响;对轴向间隙内部流动的压力和速度分布图进行分析,得出大约在85mm≤r≤102mm区域内,存在较大的漩涡,使得轴向间隙外的高压液体不易向内流,从而使轴向力平衡装置的泄漏量很少;对轴向间隙内部流场沿径向的压力分布数据进行分析,采用数据拟合方法得到曲线方程,绘出轴向间隙内部流场的压力沿径向的分布曲线图。 再其次,分析比较两种方法计算得到的压力分布曲线,从曲线中可以看出两者比较接近,且抛物线比较平坦,并提出用线性分布替代理论压力分布曲线,可满足工程应用。 最后,针对工程实例,用理论压力分布曲线和理想直线分别计算了剩余轴向力,分别为122.5N和157.8N,且平衡轴向力能力都达到99%左右;为了更能说明问题,并与开平衡孔方法平衡轴向力相比较,可以看出新型轴向力平衡装置轴向力平衡能力很强,更能满足工程实际。更多还原

【Abstract】 The axial thrust magnitude must be one of the important factors which impact the operational stability and life in the application process of the pump. Information from the large amount of documentation, it is easy to see that the existing balance devices are subject to a certain degree restrictions in the balance capacity and the application scope. And the study of axial thrust formula has always been weak in the design of pump. A new type axial-balance device is proposed by tracking the difficult and hot question in the water pumps industry. The principle of the new balance device balancing centrifugal pump axial thrust is studied in theory. The interior flow field of axial gap is compute by application FLUENT software, and a theoretical basis is offered to the axial thrust calculation by exploring the pressure distribution law.The main achievements are listed as fellows.The great significance of studying centrifugal pumps’ axial thrust is stated, and traditional balance methods are analyzed. A new type axial-balance device is proposed by tracking the latest progress of studying balance device.Firstly, the operation of the new type axial-balance device is illustrated. Laminar flow is supposed when the interior flow of the new type axial-balance device gap is analyzed. And the mathematic model of interior flowing are established respectively in radial and axial gap, then the theoretical pressure distribution law in the balance device interior gap and the function of leakage is gained by solving the incompressible flow N-S equation group and the continuity of flow equation and the equation of water pump, the work will be helpful to understand the calculation of axial thrust.Secondly, building the computing model of the new type axial-balance device axial-gap by applying GAMBIT software, then the interior flow field is calculated by applying FLUENT software. The impact of the various grid numbers on the result is analyzed by comparing their respective press distribution figure and radial velocity vector figure in the section. By analyzing the pressure and velocity figure of the flows within axial gap, it is found that the outer fluid of the axial gap flows uneasily to the interior and the leakage of the balance device decreases because the bigger whirlpool occurs in the radial range of the 85mm to 102mm. By analyzing the data of the pressure distribution along the radial direction and using the data fit method, gains the curve equations, then draws the graph of the pressure distribution.Thirdly, it can be seen that the two pressure distribution curves of the different calculation methods are very approximate and flat by comparing them. Linear distributionmay be fit to application in engineering calculations.Finally, aim at the project example, the theoretical pressure distribution curve and the ideality curve are applied to calculate the surplus axial thrust, and respectively 122.5N and 157.8N, and the balance capacity must reach around 99%. Comparing with the method of the drilling balance holes, it is clear that new type axial balance devices must be balanced better and accord with the engineering applications.更多还原