多級(jí)離心風(fēng)機(jī)內(nèi)部流場(chǎng)研究與結(jié)構(gòu)優(yōu)化(1)

多級(jí)離心風(fēng)機(jī)內(nèi)部流場(chǎng)研究與結(jié)構(gòu)優(yōu)化

摘   要
隨著離心風(fēng)機(jī)越來越廣泛的應(yīng)用于國(guó)民經(jīng)濟(jì)的各個(gè)方面和社會(huì)生活的諸多領(lǐng)域，多級(jí)離心風(fēng)機(jī)也變的愈來愈重要，同時(shí)，科技的發(fā)展和社會(huì)的需要對(duì)多級(jí)離心風(fēng)機(jī)的性能也提出了更高的要求。高參數(shù)、高性能和高可靠性是未來多級(jí)離心風(fēng)機(jī)的發(fā)展方向。為設(shè)計(jì)出高性能的風(fēng)機(jī)，必須深入研究其內(nèi)部流動(dòng)，進(jìn)而提出具體有效的改進(jìn)方案。然而迄今為止，罕有國(guó)內(nèi)外專家學(xué)者對(duì)多級(jí)離心風(fēng)機(jī)內(nèi)部流場(chǎng)進(jìn)行過研究，對(duì)提高多級(jí)離心風(fēng)機(jī)性能的探索也不多，基于此，本課題依賴 CFD 技術(shù)的優(yōu)點(diǎn)，以工程流體力學(xué)常用軟件 Fluent6.3 為主要工具，對(duì)三級(jí)離心風(fēng)機(jī)的內(nèi)部流場(chǎng)進(jìn)行了研究，并對(duì)提高多級(jí)風(fēng)機(jī)效率的途徑與方法進(jìn)行了探索。本論文做的主要工作如下：
1、對(duì)當(dāng)前國(guó)內(nèi)外離心風(fēng)機(jī)的研究現(xiàn)狀和發(fā)展方向進(jìn)行了介紹；
2、推導(dǎo)了三級(jí)離心風(fēng)機(jī)內(nèi)部流動(dòng)的控制方程和湍流方程，并介紹了近壁區(qū)域的處理方法及基本方程的離散方法；
3、根據(jù)假設(shè)條件建立了三級(jí)離心風(fēng)機(jī)數(shù)值計(jì)算的幾何模型、網(wǎng)格模型，通過對(duì)比方式對(duì)求解參數(shù)進(jìn)行了設(shè)置，對(duì)設(shè)置好的模型進(jìn)行了內(nèi)部流場(chǎng)的計(jì)算；
4、根據(jù)計(jì)算結(jié)果對(duì)設(shè)計(jì)工況、不同轉(zhuǎn)速、不同管道出口大小時(shí)風(fēng)機(jī)內(nèi)部流動(dòng)特點(diǎn)進(jìn)行了分析與比較，發(fā)現(xiàn)了內(nèi)部流動(dòng)的缺陷，并得出了不同工況下風(fēng)機(jī)性能曲線；
5、對(duì)采用不同葉片數(shù)組合時(shí)三級(jí)離心風(fēng)機(jī)的內(nèi)部流動(dòng)和性能進(jìn)行了分析與比較，據(jù)此研究了各級(jí)葉輪葉片數(shù)的匹配特性，并找到了效率更高的葉片數(shù)組合，表明通過此想法來提高風(fēng)機(jī)效率是可行的；
6、利用 CFturbo 對(duì)原風(fēng)機(jī)單級(jí)葉輪進(jìn)行了建模，預(yù)測(cè)了該葉輪的性能曲線，并通過改變參數(shù)對(duì)該葉輪進(jìn)行了結(jié)構(gòu)優(yōu)化，優(yōu)化后的葉輪性能提高。
 
關(guān)鍵詞：多級(jí)；離心風(fēng)機(jī)；數(shù)值計(jì)算；流場(chǎng)；優(yōu)化 ;石家莊風(fēng)機(jī)廠

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