煤液化高温液控阀空蚀失效预测方法研究

发布时间：2018-01-25 22:45

本文关键词： 煤液化液控阀空蚀机理数值模拟空蚀预测　出处：《浙江理工大学》2011年硕士论文　论文类型：学位论文

【摘要】：煤液化高温液控阀具有进出口压降大、介质流速高、操作频繁和运行工况多变等特点,其空蚀损伤十分严重。现有的科研攻关主要集中在通过材质升级和表面强化等手段提高阀体的抗空蚀性能,却收效甚微,至今德国SchuF阀的使用寿命不足1个月。本文在空蚀机理研究的基础上,针对液控阀的实际运行工况、流体物性和结构参数,开展空化流动的数理建模和数值分析,完成了空蚀失效的定量预测,为液控阀的结构和操作优化提供参考。本文从空蚀机理出发,基于空蚀损伤的力学作用机制,构建了近壁面单空泡变形和溃灭的数理模型,计算得到了空泡变形过程中泡壁的运动规律及其溃灭过程中产生的高速微射流和冲击压力;在此基础上,完成了在近壁面、附壁面、无限远场和成对空泡等环境特征下空泡溃灭过程的数值计算,并重点分析了在近壁面状态下空泡至固壁距离、空泡内外压力差、表面张力系数、液体粘性和来流等因素对空泡溃灭过程的影响;在空蚀机理研究的基础上,以煤液化热高分液控阀为研究对象,构建了空化流动的计算模型;运用Aspen软件,计算流体的物性参数,运用Fluent软件,获得两种典型结构的液控阀内部的流速、压力和气相分率等关键流体动力学参数的分布规律,完成了液控阀空蚀失效区域的定量计算,并结合液控阀的典型失效案例,验证了数值模拟方法的可靠性。同时,对比分析了进出口压力、操作温度、阀口开度、固体颗粒、阀芯角度等参数对空化区域和强度的影响,完成了液控阀的空蚀失效预测。本文的研究方法还可推广应用于煤液化装置其它设备、管道、泵阀的空蚀失效预测、结构优化设计、风险评估和寿命预测等,为煤液化装置的设计选材和安全运行提供技术支持。本论文创新性研究在于:1)数值分析了空泡在不同环境下的溃灭特性,捕捉到空泡在各溃灭瞬间的形态特征,完成了空蚀力学作用机制的定量计算,并对空泡溃灭的各影响因素进行定量分析;2)同时分析空泡内外压力差和液体流动对空泡溃灭的影响,并完成了双空泡溃灭特性的初步研究;3)采用煤液化热高分液控阀的实际操作参数和流体物性,完成了液控阀的空蚀失效预测,使计算结果更加接近工程实际。同时,考虑了固体颗粒相与空化流场间的相互作用,分析了颗粒的存在对空化流场的影响。?
[Abstract]:Coal liquefaction of high temperature liquid control valve with pressure drop, high flow rate of medium, frequent operation and various operating conditions and other characteristics, the cavitation damage is very serious. The current research focuses on improving the performance of anti cavitation valve by upgrading the material and surface strengthening method, but have little effect, since the German SchuF valve life is less than 1 months. Based on the study of the cavitation mechanism, according to the actual operation condition of hydraulic control valves, fluid properties and structural parameters, carry out mathematical modeling and numerical analysis of cavitation flow, completed the quantitative prediction of cavitation failure, provide a reference control structure and operation optimization of the valve for liquid.
This article from the mechanism of cavitation, mechanical mechanism of cavitation damage based on building the mathematical model of single bubble deformation and collapse near the wall, to calculate the deformation of bubble movement and its collapse of bubble wall in the process of high speed micro jet and impinging pressure; on this basis, completed in the past the wall of the wall, numerical calculation of infinite bubble collapse process of the far field and the environment of another bubble, and analyzed in the near wall to wall distance under the condition of cavitation, cavitation and pressure difference, surface tension coefficient, the influence of liquid viscosity and flow on bubble collapse in the process; based on the cavitation mechanism, coal liquefaction heat high hydraulic control valve as the research object, constructs the calculation model of cavitating flow; using the Aspen software, the calculation of physical parameters of fluid, the use of Fluent software, obtained two kinds of typical structure of hydraulic control The valve internal flow, pressure distribution and key hydrodynamic parameters rate, the hydraulic control valve cavitation failure area of quantitative calculation, combined with the typical hydraulic control valve failure case, verify the reliability of the numerical simulation. At the same time, comparative analysis of the import and export pressure, operating temperature, valve port the opening degree of solid particles, effect of valve angle on cavitation area and intensity, completed the cavitation liquid control valve failure prediction. The method can also be applied to other coal liquefaction unit equipment, pipeline, valve cavitation erosion failure prediction, structural optimization design, risk assessment and life prediction. Provide technical support for the design of material and safe operation of coal liquefaction device.
The main innovation in this paper lies in: 1) the numerical analysis of the characteristics of bubble collapse in different environments, to capture the bubble morphology in the collapse of the moment, to complete the quantitative cavitation mechanical mechanism is calculated, and the factors affecting the bubble collapse by quantitative analysis; 2) and analysis of the influence of cavitation pressure difference between the inside and outside and the liquid flow on the bubble collapse, and completed the preliminary study on the characteristics of double bubble collapse; 3) the actual operating parameters and fluid properties by coal liquefaction hot high pressure hydraulic control valve, the hydraulic control valve cavitation failure prediction, the calculation results are more close to the actual project. At the same time, the interaction of solid particles and the cavitation flow considering Inter, analyzed the influence of the presence of the particles of cavitation flow.?

【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH137.52

【引证文献】