【作者】 王立红；

【导师】 金英子；

【作者基本信息】 浙江理工大学 ， 流体机械及工程， 2010， 硕士

【摘要】 近年来,随着电子产品的不断小型化和高性能化,小型换热风扇的性能便成为影响电子产品性能和寿命的决定因素。因此,正确计算和测试换热风扇内部流动特性和性能及噪声、找出影响风扇性能的主要因素,将为小型轴流风扇的结构设计提供重要依据。本文通过三维软件改变小型风扇的安装角、叶顶间隙、叶片数而得到不同的模型,利用CFD方法对不同模型进行三维数值模拟,得到不同结构参数下小型风扇的静态特性及内部流体的速度矢量及压力、涡强分布,为提高风扇性能作了一定的探索性研究。初步明确了不同结构参数对风扇内部流动和静态特性的影响。1、在原有叶轮几何外形基础上进行修改,对三种不同安装角的流场进行数值计算,详细分析了安装角改变时流量变化的特性曲线。此外还分析了压力面进口和吸力面速度变化及不同叶顶间隙位置回转面速度、涡强的变化。2、通过不同叶顶间隙进行数值模拟,分析了不同叶顶间隙时流量变化曲线。同时分析了同一个模型中,轮毂面到机闸内表面之间不同回转面涡强的变化趋势及不同叶顶间隙时,相同径向方向半径回转面上的涡强变化,即随着叶顶间隙的增加而减弱,且涡核逐渐沿吸力面弧线向下游移动。3、对不同叶片数目模型进行数值计算,分析了叶片数目变化时流量变化的特性曲线及压力面、吸力面及叶顶的静压分布,此外还分析了叶片数不同时子午面的速度分布。小型风扇的内部流场和性能的研究是和流体力学、流体机械、材料学等有关的非常复杂的理论问题,本文的研究成果主要应用于小型风扇的内部流场及静特性分析,可为改善小型风扇的性能提供一定的理论依据。更多还原

【Abstract】 In recent years, along with electronic products microminiaturization and higher performance, cooling fans used for heat-dissipation have become key points of performance and life span of product. The correct computation and test for interior flow flied is very important for finding out the primary influence factor for the ventilator performance and the noise. It will provide an important basis for the axial-flow fan’s structural design of the axial-flow fan to establish a design system in order to improve the performance and reduce the noise.The different models were obtained by changing stagger angle, tip clearance, blade numbers of fans in the three dimensional software. In order to improve the performance of the fan made many exploratory research, three-dimensional numerical simulation of different models were carried out using CFD method, and the static characteristics of a small fan and the distributions of velocity vector and pressure, vortex intensity were obtained. Based on these, make it clear initially that how the different structural parameters affect on the internal flow field and static characteristics of the fan.1、Numerical simulation of different models were carried out on three models with different stagger angle which got by modifying geometric parameters on the original impeller. Based on the results, a detailed analysis of characteristic curve was going on them. What’s more, the change of the velocity of pressure surface inlet and suction surface were analyzed, velocity and vortex intensity of revolution surface when tip clearance is different also were discussed.2、Carries on the numerical simulate to different tip clearance models, analyzing flow rate characteristic curve when the tip clearance is different. For a model, trend of vortex intensity on revolution surface which from hub surface to power-break surface was discussed. For different tip clearances, the change of vortex intensity in the revolution surface that the radial position same was observed, that is vortex intensity is reduce with the increase of tip clearance, and the position of vortex core from moves along the suction surface arc.3、Carries on the numerical simulate to different blade number models, analyzing flow rate characteristic curve and static pressure distribution of pressure surface, suction surface and top of blade when the numbers of blade is change. Moreover, velocity distribution of meridian plane was analyzed with blade numbers are different.The inner flow and performance study of micro-axial fan was a complex problem with reference to fluid mechanics, fluid machinery and material science. The research results in this paper were applied in static characteristic analysis and interior flow field of small axial fan, and the theoretical basis can be provided to improve the performance of small axial fan in some extent.更多还原