离心风机叶轮的有限元分析及优化

发布时间：2018-08-16 09:56

【摘要】：离心风机是将机械能转化为气体的压力能，提高气体压力并排送气体的机械。离心风机广泛应用于矿业、建筑、钢铁、发电和农业等国民生产生活领域。叶轮和叶片是离心风机的重要工作部件，它的强度影响风机的安全运行，其结构参数决定风机的性能。传统方法计算叶轮和叶片的应力比实际值小，设计出来的风机会出现事故。离心风机设计时较多的采用相似设计法，没有优化风机的相关结构参数，使风机性能不够理想。本文运用现代设计方法对叶轮和叶片进行强度计算、结构参数优化和流场模拟，为离心风机的设计和改进提供参考。（1）以油菜籽分选机上用的离心风机为研究对象，根据风机各零件的制造图纸，利用Pro/E分别建立了离心风机及其零部件的三维实体模型和风机内流场流道的三维模型。（2）借助有限元分析软件ANSYS对叶轮进行静力分析，得到叶轮的应力、应变分布云图。将有限元分析结果与传统计算方法结果对比，验证了传统计算方法的局限性。两种计算方法都表明该风机叶轮满足强度条件，，但有限元分析结果更接近于实际。（3）利用ANSYS对叶轮进行了模态分析，得到叶轮的前八阶固有频率和对应的振型图。叶轮的干扰频率小于叶轮的各阶固有频率，因此叶轮不会发生共振。（4）建立了以风机在设计流量下的流力损失最小为目标函数，叶轮部分结构参数为变量的优化数学模型，借助MATLAB软件的优化工具箱对叶轮结构参数进行了优化，得到最小流力损失和此时的叶轮结构参数，将流力损失由110.13Pa减小为75.51Pa。优化结果表明将优化设计方法运用于风机设计中可以有效提高风机性能。（5）利用CFD软件FLUENT对离心风机内部流场进行了数值模拟，得到了风机内部流场各个部分的压力云图和速度矢量图。通过速度矢量图了解风机内空气流动情况，通过压力云图可以预测风机的实际性能。计算结果可以为风机设计及改进提供参考。
[Abstract]:Centrifugal fan is a machine that converts mechanical energy into gas pressure energy and increases gas pressure. Centrifugal fans are widely used in mining, construction, steel, power generation and agriculture and other areas of national production and life. Impeller and blade are important working parts of centrifugal fan, its strength affects the safe operation of fan, and its structural parameters determine the performance of fan. The traditional method for calculating the stress of impeller and blade is smaller than the actual value. In the design of centrifugal fan, the similar design method is often used, and the relevant structural parameters of the fan are not optimized, so the performance of the fan is not ideal. In this paper, the strength calculation, structural parameter optimization and flow field simulation of impeller and blade are carried out by using modern design method, which provides a reference for the design and improvement of centrifugal fan. (1) the centrifugal fan used in rapeseed separator is taken as the research object. According to the manufacturing drawings of each part of the fan, the three-dimensional solid model of centrifugal fan and its components and the three-dimensional model of the flow field in the fan are established by using Pro/E. (2) the static analysis of impeller is carried out by means of the finite element analysis software ANSYS. The distribution of stress and strain of impeller is obtained. The limitation of the traditional method is verified by comparing the results of finite element analysis with those of the traditional method. Both methods show that the fan impeller satisfies the strength condition, but the finite element analysis results are closer to reality. (3) Modal analysis of impeller is carried out by using ANSYS, and the first eight natural frequencies and corresponding mode shapes of impeller are obtained. The disturbance frequency of impeller is smaller than the inherent frequency of impeller, so the impeller will not resonate. (4) the objective function is to minimize the flow loss of fan under the design flow rate. In this paper, the optimal mathematical model of impeller structural parameters is obtained by using the optimization toolbox of MATLAB software. The minimum fluid force loss and the impeller structural parameters are obtained, and the fluid loss is reduced from 110.13Pa to 75.51Pa. The optimization results show that the application of optimal design method to fan design can effectively improve the performance of fan. (5) the flow field of centrifugal fan is numerically simulated by using CFD software FLUENT. The pressure cloud diagram and velocity vector diagram of each part of the flow field in the fan are obtained. The air flow in the fan can be understood by velocity vector chart and the actual performance of the fan can be predicted by the pressure cloud diagram. The results can provide reference for fan design and improvement.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH432

【参考文献】