涡旋压缩机微间隙泄漏及平衡重功率损耗的数值分析

发布时间：2018-09-18 22:00

【摘要】：涡旋压缩机是一种新型高效、低噪的容积式压缩机,与其他形式的压缩机相比较在许多方面有着较大的优势,随着加工制造技术的不断发展,涡旋压缩机已广泛应用于制冷空调、动力工程等领域。由于自身的结构特点,涡旋压缩机的内泄漏是影响其性能的主要因素;压缩机曲轴上设有平衡重用于平衡动涡旋产生的旋转惯性力及其力矩。本文重点研究了圆渐开线涡旋压缩机微间隙泄漏特点及平衡重旋转时的功率损耗。首先根据圆渐开线涡旋压缩机动、静涡旋齿型线的几何特点,建立了涡旋压缩机吸气容积、排气容积、容积比、未封闭吸气容积等几何参数的数学模型。在全面分析压缩机的结构、影响压缩机性能及工作过程的各种因素的基础上,建立了考虑内部泄漏的压缩机工作过程热力学模型,并通过对微间隙气体泄漏特点的研究,依据流体力学N—S方程、连续方程、状态方程等,建立了涡旋压缩机内部切向泄漏、径向泄漏以及动涡旋与支架体间的泄漏数学模型。涡旋压缩机的内泄漏间隙通常只有几十微米,泄漏流动理论数学模型并没有考虑微通道表面粗糙度对气体流动特性的影响。以涡旋压缩机纯气体内泄漏模型为研究对象,在微尺度、低压差泄漏流动过程的基础上,采用计算流体动力学方法,应用FLUENT软件分析了微间隙表面均匀锯齿状粗糙元的高度、分布密度和布置方式对于充分发展的泄漏流动的影响。结果表明,较大的粗糙元高度和较大的微元分布密度可以有效增大泄漏微流体流动阻力,降低泄漏流速。为了平衡动涡旋偏心设置所产生的旋转惯性力及其力矩,涡旋压缩机曲轴上设有平衡重,平衡重在旋转过程中与平衡腔内气体相互作用会消耗一部分功率。利用FLUENT软件的滑移网格模型,计算得到了不同结构平衡重在转速范围内消耗的功率,并对比研究了平衡重结构形状对耗功的影响。将平板型平衡重和带凸台平衡重径向侧面倒圆角既不会降低平衡效果,又使功耗最小。
[Abstract]:Scroll compressor is a new type of displacement compressor with high efficiency and low noise. Compared with other types of compressor, scroll compressor has great advantages in many aspects. With the development of manufacturing technology, Scroll compressor has been widely used in refrigeration and air conditioning, power engineering and other fields. The internal leakage of the scroll compressor is the main factor affecting its performance due to its structural characteristics and the balance weight is arranged on the crankshaft of the compressor to balance the rotating inertia force and its torque produced by the moving vortex. In this paper, the characteristics of microgap leakage of circular involute scroll compressor and the power loss of balanced heavy rotation are studied. Firstly, according to the geometric characteristics of the moving and static vortex profile of the circular involute scroll compressor, a mathematical model of the suction volume, exhaust volume, volumetric ratio and unclosed suction volume of the scroll compressor is established. Based on the comprehensive analysis of the compressor structure, various factors affecting the compressor performance and working process, the thermodynamic model of the compressor working process considering internal leakage is established, and the characteristics of gas leakage in the micro gap are studied. Based on the N-S equation, continuous equation and state equation of hydrodynamics, the mathematical models of internal tangential leakage, radial leakage and leakage between moving vortex and support are established. The internal leakage clearance of scroll compressor is usually only several tens microns. The effect of surface roughness of microchannel on gas flow characteristics is not taken into account in the theoretical model of leakage flow. Taking the internal leakage model of pure gas of scroll compressor as the research object, on the basis of micro-scale and low-pressure difference leakage flow process, the height of uniform sawtooth rough element on microgap surface is analyzed by using computational fluid dynamics method and FLUENT software. The effect of distribution density and layout on fully developed leakage flow. The results show that the larger rough element height and larger microelement distribution density can effectively increase the flow resistance and decrease the leakage velocity. In order to balance the rotational inertia force and its torque caused by the eccentric setting of the moving vortex, there is a balance weight on the crankshaft of the scroll compressor, which consumes a part of the power when the balance weight interacts with the gas in the balance chamber during the rotation process. By using the sliding grid model of FLUENT software, the power consumption in the range of rotational speed of different structural balance weights is calculated, and the influence of the balance weight structure shape on the power consumption is compared. The balanced weight of flat plate and the counterweight with punch can not reduce the balance effect and minimize the power consumption.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH45

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