【作者】 张香红；

【导师】 贾月梅；

【作者基本信息】 太原理工大学 ， 流体力学， 2007， 硕士

【摘要】 本课题来源于国家自然科学基金项目(50345022)和山西省自然科学基金项目(20041058)，主要分析研究螺旋流光整加工技术。气-固两相螺旋流光整加工技术是利用气体的旋转运动，推动固体颗粒作螺旋运动，使固体颗粒在离心力的作用下对工件孔内表面进行滚压、磨削等，最终实现对工件孔内表面光整加工的目的。此项新技术的研究将有助于传统工艺和现有光整加工工艺的进一步完善。由于实验条件的限制，单纯通过试验来研究螺旋流光整加工的性能不仅周期长而且费用高。随着计算机技术的发展，数值模拟发挥着越来越大的作用，它有资金投入少、设计计算速度快、信息完全、仿真能力强等优点。数值模拟是基于流体力学和计算流体力学的基本理论，建立各种复杂条件下的基本守恒方程组，确定适用模型的定解条件，用数值计算方法直接求解这些联立的非线性偏微分方程组，从而得到整个流场中各变量的分布。因此，以数值模拟为主来研究光整加工工件孔内螺旋流的流动规律、固体颗粒的运动轨迹等，对改善螺旋流光整加工工件的结构，很有工程应用价值。本文主要内容有：阐述了两相流的基本理论；分析了等直径孔内螺旋流的基本特征、衰减特性、压力分布及螺旋流中颗粒受到的摩擦力；研究了用于螺旋流的湍流模型及数值计算方法；应用FLUENT软件，对气流场采用基于各向异性的雷诺应力湍流模型，对颗粒采用能反映颗粒运动复杂经历和与壁面碰撞的随机轨道模型，进行了等直径孔内多种情况下气流场、颗粒运动轨迹、旋流强度等的数值模拟，得到了如下主要结论：1．等直径工件孔内的螺旋流场，其切向速度分布具有组合涡的特点，以最大切向速度点形成的面为界，内部是强制涡，外部是自由涡，其轴对称性很好。压力分布在中心轴处最小，甚至出现负压。旋涡强度沿着轴向逐渐减弱。2．颗粒粒径、气体流量、喷嘴螺旋升角的变化对颗粒的轨迹都有影响。颗粒粒径增加，气体流量减少，喷嘴螺旋升角变大，都会使颗粒形成的螺旋圈数变少，使颗粒较早的离开等直径工件孔。3．等直径工件孔内壁面受力随颗粒个数的增加及气流流量的增加而增大。4．由于气体的粘性比液体的粘性小及气体的可压缩性，所以相同条件下，气流场的切向速度和旋涡强度都比液流场的强。本文数值模拟的结论将为以后研究此项课题奠定良好的基础，也能为实验装备的设计提供一定的依据。更多还原

【Abstract】 The research is supported by the nation and Shanxi local science fund project, to research spiral flow finishing technique mostly. Gas-particle two-phase spiral flow finishing technique is to impel solid particles to swirl via spiral flow of gas, making solid particles to cut and rub the hole inner-surface by means of centrifugal force, then the quality of the hole inner-surface is improved. It is helpful to perfect the traditional and existing finishing technology ulteriorly.As the restriction of the equipment in common use, the study on performance of spiral flow finishing process only by experiment is not only long term, but also expensive. With the development of computer, numerical simulation plays increasing function. The numerical simulation has many merits ,for example, the devoted finance is less, the speed of design and computation is quick, the information is full and the ability of emulation and simulation is better. The numerical simulation is based on the theory of fluid dynamics and computational fluid dynamics. We set up a set of basic conserved equations in diversified complex conditions, make the assured conditions of the selected model, then solve direct these simultaneous non-linearity partial-differential equations, and accordingly get the distribution of every variables in the whole flow field. Therefore, studying on the law of fluid and the particle tracks in spiral flow of finishing process workpiece by numerical simulation, and then improving its configuration, and so have a important application worth in engineering.The thesis concentrate to the following contents: expatiate the basic knowledge of the two-phase; analyze the basic character of spiral flow, its characteristic to attenuate, the distribution of the static pressure in even diameter hole ; the friction force of particle in spiral flow; study the turbulent model and the method of numerical computation for spiral flow; do numerical simulation for the flow of gas, moving tracks of particles and vorticity magnitude,using Reynolds Stress Model based on anisotropy for gas flow field, and stochastic tracking model based on Lagrangian frame of reference for solid phase, which can reflect complex movement experience and collision of particle and wall via FLUENT. We have got the following conclusions from the simulation in the thesis:(1) In even diameter hole, the tangental velocity has the characteristic of combination vortex; with the boundary of points for maximal speed, the insides is norm forced vortex, the outside is norm free vortex; the axis symmetry of tangental velocity is very well. The pressure is the minimum in the center-axes, even the negative pressure. Along the axes, vorticity magnitude is much lower.(2) With the change of particle diameter, flux of gas, spiral angleαof nozzle, the tracks of particle alters. With the accretion of the particle diameter,the reduction of gas flux, the accretion ofα, the counters of spiral of particle tails off. Particle leaves off the tube earlier.(3) With the accretion of the counter of the particle and the gas flux, the force of the wall getted increase in even diameter hole.(4) Because the gas viscidity is smaller than the liquid viscidity and air is compressible, so in the same conditions, the tangental velocity and vorticity magnitude of gas is greater than liquid.The result of this simulation will accumulate some helpful materials for later experiment and equipment designed.更多还原