适用于幂律流体螺旋结构液膜密封性能研究

发布时间：2018-01-11 20:26

本文关键词：适用于幂律流体螺旋结构液膜密封性能研究　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：螺旋结构液膜密封(螺旋槽上游泵送机械密封和普通螺旋密封)具有优良的性能而广泛用于石油化工行业中的旋转机械上。考虑到石油化工行业中常见的液相介质大多会呈现出非牛顿流体的特征。本文采用解析算法和数值模拟两种方法,分别对用于密封幂律流体的螺旋槽上游泵送机械密封和螺旋密封的性能进行分析研究,以期望得到更符合生产实际的情况,从而为用于密封幂律流体的螺旋结构液膜密封的设计和应用提供理论依据。1.对于螺旋槽上游泵送机械密封:(1)考虑到液体在泵送进螺旋槽的过程中会在槽端部产生压力损失的"端部效应",引入等效半径方程,对利用窄槽理论推得的密封端面液膜压力控制方程中槽坝交界处压力进行修正,得到考虑"端部效应"修正的近似解析算法,并将其所得结果与数值模拟结果进行对比,通过了算法合理性验证。进而分析端部效应对不同几何结构参数和操作参数的螺旋槽上游泵送机械密封性能的影响程度。结果表明:当台槽宽比γ≥0.8、槽深hg≤25μm、轴转速ω≤7000r/min时,而螺旋角α、坝宽比Lr、密封压差Δp、密封平衡膜厚h2无论如何变化时,可不用考虑端部效应对密封性能的影响。(2)基于Muijderman推导牛顿液体润滑轴承性能求解的解析法,选用端部效应影响较弱的密封模型,将幂律流体二维定常流动雷诺方程和流量方程分别替代牛顿流体二维定常流动雷诺方程和流量方程,得到适用于幂律流体螺旋槽上游泵送机械密封性能求解解析法,并将其所得结果与数值模拟结果进行对比,通过了算法合理性验证。进而以此分析介质物性参数、密封操作参数和几何结构参数对密封性能的影响。结果表明:流性指数、稠度系数、密封压差、轴转速、密封平衡膜厚、槽深、螺旋角、台槽宽比和坝宽比对密封的开启力和泄漏率影响显著。2.对于普通螺旋密封:基于Crease推导密封介质为牛顿液体时螺杆式螺旋密封封液能力的方法,将幂律流体二维定常流动速度分布方程替代牛顿流体二维定常流动速度分布方程,得到适用于幂律流体螺杆式螺旋密封封液能力近似解析法,并将其所得结果与数值模拟结果进行对比,通过了算法的合理性验证。进而以此分析介质物性参数、密封操作参数和几何结构参数对密封性能的影响。结果表明:流性指数、稠度系数、轴转速、螺旋角、相对槽宽和相对槽深对密封的封液能力影响显著。
[Abstract]:The spiral structure of liquid sealing (upstream pumping mechanical seal and spiral seal) has excellent properties and is widely used in rotating machinery in petroleum chemical industry. Considering the oil industry in the most common liquid phase medium showing the characteristics of non Newton fluid. This paper uses two methods analytic method and numerical simulation respectively, to analyze the performance of mechanical seal and spiral seal for spiral groove upstream of the pump seal of power-law fluid, to get more accord with the actual production situation, which is used for the design and application of liquid membrane spiral sealing structure of power-law fluid sealing and provide a theoretical basis for.1. upstream pumping mechanical seal: (1) considering the liquid in the pump to the spiral groove in the process of the end of the trough of the pressure loss of "end effect", the introduction of the equivalent radius of the narrow groove theory equation. Seal liquid film pressure control equation in slot dam at the junction of the pressure correction are derived, are considered "approximate analytical algorithm to modify the end effect", and the results obtained with the numerical simulation results are compared by the algorithm. And then verify the rationality analysis of spiral groove upstream pump end effect of different geometric parameters and the influence of operating parameters to send mechanical sealing performance. The results show that when the groove width ratio of more than 0.8 Taiwan gamma, Hg groove depth less than or equal to 25 mu m, shaft rotate speed is less than or equal to 7000r/min, and the spiral angle, dam width ratio Lr, seal pressure difference P, sealing balance film thickness H2 in any case changes, can without considering the influence of end effect on the sealing performance. (2) analytical derivation of the Muijderman Newton liquid lubricated bearing performance solution based on the selection of end effect of weak seal model, power-law fluid will be two-dimensional unsteady flow Reynolds equation and flow equation Don't replace Newton fluid Reynolds equation and flow equation of two-dimensional steady flow, applied to send mechanical sealing performance analysis method in solving the power-law fluid in spiral groove upstream of the pump, and the results obtained with the numerical simulation results are compared by the algorithm. And then verify the rationality analysis of dielectric property parameters, operating parameters and geometric structure of seal effect of parameters on the sealing performance. The results show that the flow index, consistency coefficient, seal pressure, shaft speed, sealing balance film thickness, spiral angle, groove depth, Taiwan groove width ratio and dam width on the seal opening force and leakage rate significantly affected.2. for ordinary spiral seal sealing medium is derived: Crease Newton liquid screw spiral sealing capability based on the two-dimensional unsteady flow of power-law fluid velocity distribution equation of two-dimensional unsteady flow instead of Newton fluid velocity distribution equation, to apply to power law Screw type spiral fluid sealing capability approximate analytical method, and the results were compared with the results of numerical simulation, the rationality validation algorithm. Then based on the analysis of the physical parameters of medium, sealing the operating parameters and geometric structure parameters on sealing performance is analyzed. The results show that the flow index, consistency coefficient. The shaft speed, spiral angle, groove width and the relative effect of relative groove depth on sealing capability significantly.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH136

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