无油涡旋压缩机腔内流场建模仿真及实验研究

发布时间：2018-07-09 19:12

本文选题：计算流体力学 + 热力学　；参考：《南昌大学》2013年博士论文

【摘要】：涡旋压缩机没有往复运动机构,体积小、重量轻、易损件少,在中小容量的压缩机中具有很大的性能优势,是高性能压缩机的主要发展方向之一。无油涡旋压缩机在结构上排除了工作介质接触润滑油的可能,可以满足医疗、食品等行业的特殊需求,但是排气量大、使用寿命长的无油涡旋压缩机制造尚存在困难。为了深入了解涡旋压缩机的运行机理,从原理上指导涡旋压缩机的设计,分析无油涡旋压缩机的内部流动过程显得非常重要。本课题运用热力学理论和计算流体力学方法研究了涡旋压缩机的内部流动过程,获得了涡旋压缩机压缩腔内压力、温度、流速的瞬态分布,为高性能涡旋压缩机的设计提供参考。本文首先介绍了无油涡旋压缩机的结构和工作原理,根据压缩腔的几何形状,将热力学和传热学作为理论基础,用质量守恒和能量守恒等定律,分析了无油涡旋压缩机压缩腔的容积变化过程和热力工作过程,建立了一种全面考虑了压缩过程中的换热和泄漏现象且适用于无油涡旋压缩机的实用热力学仿真模型,并用实验验证了该数学模型的准确性。然后通过分析涡旋压缩机流场模拟的数学模型和数值计算方法,将涡旋压缩机排气过程视为准静态过程,用计算流体力学的稳态方法来分析涡旋压缩机。选定了合理的排气过程几何模型,检验了网格的无关性,用湍流模型模拟了排气流动过程。该模拟给出了无油涡旋压缩机压缩腔内不同轴向截面内的速度场、不同涡旋转角时的速度场及包含排气管在内的三维速度场。再将涡旋压缩机进行几何简化,用二维模型研究了压缩腔内部的动态流动过程。克服了涡旋压缩机压缩腔几何形状复杂的困难,获得了适合涡旋压缩机内流场仿真的网格形式。该模拟采用了基于局部弹性变形与网格重划的CFD动网格技术,以理想气体为工作介质,满足流体控制方程及气体状态方程,采用了RNG κ-ε湍流模型。该模拟详细展示了二维涡旋压缩机吸气、压缩、排气过程的压缩腔内压力、温度、速度的分布情况,对比了不同转速时的温度、压力、速度的变化规律。用实验数据验证了数值模拟的正确性,保证了结果的真实有效。最后,设计了涡旋压缩机的三维简化几何模型,通过网格性能对比获得了适合三维涡旋压缩机内流场模拟的三棱柱网格,利用动网格技术及交界面技术完成了涡旋压缩机的三维瞬态模拟。该模拟形象地揭示了三维涡旋压缩机的内部流动规律,给出了温度、压力、流速在每个转角位置的变化过程。与实验值及二维仿真值进行了对比,分析了误差原因。无油涡旋压缩机内流场仿真形象地揭示了涡旋压缩机的内部流动规律,为深入研究无油涡旋压缩机机理,解决无油涡旋压缩机使用寿命短、排气量难以提高等问题提供了理论参考。同时,动网格技术在涡旋压缩机内流场动态模拟中的应用,探索了计算流体力学技术应用的一个新领域,拓宽了动网格技术的工程应用范围。
[Abstract]:Scroll compressor has no reciprocating mechanism , small volume , light weight and less wearing parts . It is one of the main developing directions of high performance compressor .

In this paper , the structure and working principle of the oil - free scroll compressor are introduced . Based on the geometry of the compression cavity , the volume change process and the thermodynamic working process of the compression chamber of the oil - free scroll compressor are analyzed by using the laws of mass conservation and energy conservation , and a practical thermodynamic simulation model for the oil - free scroll compressor is established , and the accuracy of the mathematical model is verified by experiments .

The exhaust process of scroll compressor is regarded as quasi - static process by analyzing the mathematical model and numerical calculation method of the flow field simulation of scroll compressor . The reasonable exhaust process geometry model is selected to test the independence of the grid , and the exhaust flow process is simulated by using the turbulence model . The simulation gives the velocity field in different axial sections in the compression cavity of the oil - free scroll compressor , the velocity field at different swirl angles and the three - dimensional velocity field including the exhaust pipe .

In this paper , the dynamic flow process inside the compression chamber is studied by using two - dimensional model , and the dynamic flow process in the compression chamber is studied by using the two - dimensional model .

In the end , the three - dimensional simplified geometric model of scroll compressor is designed , and the three - dimensional transient simulation of scroll compressor is obtained by grid performance comparison . The three - dimensional transient simulation of scroll compressor is accomplished by dynamic grid technique and interface technology .

In this paper , the internal flow law of scroll compressor is revealed by the flow field simulation in the oil - free scroll compressor , which provides a theoretical reference for deeply studying the mechanism of oil - free scroll compressor , and solves the problems of short service life and difficulty in air displacement of the oil - free scroll compressor .
【学位授予单位】：南昌大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH45

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