基于流固耦合的离心通风机叶轮动力特性分析

发布时间：2018-07-17 03:53

【摘要】：离心通风机是工业生产部门使用非常广泛的一类机械设备,在电力、石油、化工等领域发挥着重要作用,其能否安全运行直接关系着各个生产部门的经济效益。叶轮是风机最为关键的部件,它的强度不足或疲劳破坏会造成风机事故。传统的叶轮强度计算方法对叶轮进行了大量的简化,导致计算误差一般较大,这给评估叶轮的安全性带来一定的困难,而采用有限元法可以较好地解决这一问题。本文以G4-73No.8D离心通风机叶轮为研究对象,考虑风机工作时叶轮变形对流场的影响和三种载荷离心力、重力和气动力对叶轮变形和应力的影响,采用计算流体力学软件CFX对风机流场进行数值模拟、有限元软件ANSYS对叶轮结构场进行数值模拟,并以MFX-ANSYS/CFX为数据耦合平台,应用弱耦合方法对叶轮进行流固耦合数值模拟。模拟结果表明：流固耦合作用对风机流场影响很小,可以忽略不计,但对叶轮的变形和应力大小具有一定影响,其中使叶轮最大总变形量降低2.5%,最大等效应力值提高3.6%。考虑预应力效应使叶轮固有频率提高,但各阶固有频率提高幅度不同,最大提高幅度为2.6%,在叶轮所受的三种载荷中,离心力对固有频率的提高起决定作用,其余两种载荷的影响可以忽略不计。对叶轮的频率余量进行了计算,研究发现叶轮的固有频率部分落入局部共振区域,但由于该区域的变形量和等效应力都较小,且等效应力远小于叶轮材料的疲劳极限,所以不会发生叶轮的疲劳破坏。
[Abstract]:Centrifugal fan is a kind of mechanical equipment widely used in industrial production department. It plays an important role in electric power, petroleum, chemical industry and so on. Its safe operation is directly related to the economic benefit of each production department. Impeller is the most important component of fan. Its insufficient strength or fatigue failure will cause fan accident. The traditional calculation method of impeller strength has made a great deal of simplification of impeller, which leads to a large calculation error, which brings some difficulties to evaluate the safety of impeller, and the finite element method can solve this problem well. In this paper, the impeller of G4-73 No. 8D centrifugal fan is taken as the research object. The influence of the flow field of impeller deformation and three kinds of load centrifugal force, gravity and aerodynamic force on the deformation and stress of impeller are considered. The flow field of the fan is simulated by CFX, and the impeller structure field is simulated by the finite element software ANSYS. Using MFX-ANSYS / CFX as the data coupling platform, the weak coupling method is used to simulate the fluid-solid coupling of the impeller. The simulation results show that the fluid-solid coupling has little effect on the fan flow field and can be ignored, but it has a certain influence on the impeller's deformation and stress, among which the maximum total deformation of the impeller is reduced by 2.5 and the maximum equal effect force value is increased by 3.6. Considering the prestress effect, the inherent frequency of impeller is increased, but the amplitude of natural frequency of each order is different, and the maximum increase amplitude is 2.6. In the three kinds of loads to which the impeller is subjected, the centrifugal force plays a decisive role in the increase of the natural frequency. The effects of the other two loads are negligible. The frequency allowance of impeller is calculated. It is found that the natural frequency of impeller falls into the local resonance region, but the deformation and equivalent stress in this region are small, and the equal effect force is much smaller than the fatigue limit of impeller material. Therefore, there will be no fatigue damage of impeller.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH432

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