多级离心风机内部流场研究与结构优化(1)

多级离心风机内部流场研究与结构优化

摘   要
随着离心风机越来越广泛的应用于国民经济的各个方面和社会生活的诸多领域，多级离心风机也变的愈来愈重要，同时，科技的发展和社会的需要对多级离心风机的性能也提出了更高的要求。高参数、高性能和高可靠性是未来多级离心风机的发展方向。为设计出高性能的风机，必须深入研究其内部流动，进而提出具体有效的改进方案。然而迄今为止，罕有国内外专家学者对多级离心风机内部流场进行过研究，对提高多级离心风机性能的探索也不多，基于此，本课题依赖 CFD 技术的优点，以工程流体力学常用软件 Fluent6.3 为主要工具，对三级离心风机的内部流场进行了研究，并对提高多级风机效率的途径与方法进行了探索。本论文做的主要工作如下：
1、对当前国内外离心风机的研究现状和发展方向进行了介绍；
2、推导了三级离心风机内部流动的控制方程和湍流方程，并介绍了近壁区域的处理方法及基本方程的离散方法；
3、根据假设条件建立了三级离心风机数值计算的几何模型、网格模型，通过对比方式对求解参数进行了设置，对设置好的模型进行了内部流场的计算；
4、根据计算结果对设计工况、不同转速、不同管道出口大小时风机内部流动特点进行了分析与比较，发现了内部流动的缺陷，并得出了不同工况下风机性能曲线；
5、对采用不同叶片数组合时三级离心风机的内部流动和性能进行了分析与比较，据此研究了各级叶轮叶片数的匹配特性，并找到了效率更高的叶片数组合，表明通过此想法来提高风机效率是可行的；
6、利用 CFturbo 对原风机单级叶轮进行了建模，预测了该叶轮的性能曲线，并通过改变参数对该叶轮进行了结构优化，优化后的叶轮性能提高。
 
关键词：多级；离心风机；数值计算；流场；优化 ;石家庄风机厂

With  the  centrifugal  fan  are  more  and  more  widely  used  in  many  fields  of  national economy  and  social  life,  multi-stage  centrifugal  fan  has  become  increasingly  important, meanwhile,  the  performance  of  multi-stage  centrifugal  fan  also  puts  forward  higher requirements  because  of  technological  development  and  social  needs.  High-parameter, high-performance and high reliability are the direction of the next multi-stage centrifugal fan. In  order  to  design  high-performance  fan,  its internal  flow  must  be researched,  and  thus propose  concrete  and  effective  improvement  program.  So  far,  however,  rare  domestic  and foreign experts and scholars researched on the internal flow field and explored to improve the performance  of  the  multi-stage  centrifugal  fan,  based  on  this,  the  subject  relies  on  the advantages  of  CFD  technology,  using  engineering  fluid  mechanics  commonly  software Fluent6.3 as the main tool, the internal flow field of three centrifugal fan is researched, and the ways and means to improve the fan efficiency are explored. The main work done in this paper are as follows: 1. The current research situation and development direction of the centrifugal fan at home and abroad are introduced;
   2.  The  flow  equations  and  turbulence  equations  of  the  internal  flow  in  the  three-stage centrifugal fan are deduced and the methods to dispose the near-wall region and the discrete method of basic equations are described;
   3. According to the assumptions of the three-stage centrifugal fan, the geometric model and grid model are established, and solution parameters are setted by comparing, then the internal flow field is calculated;
4. According to the numerical calculation results of the design condition, different speeds and  different  pipe  outlet  sizes,  internal  flow  characteristics  are  analyzed  and  compared,  the defects  of  the  internal  flow  are  found,  and  the  fan  performance  curves  under  different conditions are obtained;
   5. The internal flow and performance of the three-stage centrifugal fan with different blade number combinations are analyzed and ompared, according to this, the matching features of the  number  of  impeller  blades  are  researched,  and  the  more  efficient  combination  of  the number of blades is found, which indicates that this idea is feasible to improve the efficiency of the fan;
   6.  The  single-stage  impeller  of  the  original  fan  is  modeled  by  using  Cfturbo,  and  the performance  curves  of  the  impeller  are  predicted,  then  the  structure  of  the  impeller  is  III optimized by changing parameters, the performance of the optimized mpeller is improved. 
Key words: Multi-stage, Centrifugal fan, Numerical calculation, Flow field, Optimization