【作者】 王宇；

【导师】 冀春俊；

【作者基本信息】 大连理工大学 ， 流体机械及工程， 2009， 硕士

【摘要】 离心压缩机因其可靠性高、体积小、质量轻等诸多优点而在国民经济各部门发挥着举足轻重的作用,但同时也消耗着大量的能源。为了满足各个工业领域对离心压缩机高负荷、高效能等日益苛刻的需求,就需要不断的提高离心压缩机研究和设计水平。由于离心压缩机结构复杂,元件数量多,以往的研究大多是将各元件分开考虑,研究其内部的流动现象;近年来,随着计算机水平的提高,越来越多的科研工作者开始关注离心压缩机级各元件之间的相互匹配,以期通过集成优化的方式来提高压缩机的整体设计水平。本文研究对象是某公司生产的百万吨乙烯项目中的丙烯压缩机和裂解气压缩机的末级结构。利用CAD软件Pro/E,CFD软件NUMECA建立起压缩机末级完整的三维流场的数值模拟分析平台。通过对丙烯压缩机末级不同D₄/D₂方案的整级模型进行数值模拟,详细地分析其内部流动特征,得出对应于该模型的最佳D₄/D₂值,并通过匹配不同的排气蜗壳结构,研究上下游元件的相互影响。按照动量矩守恒方法设计出适合末级结构的内包式等宽蜗壳,并通过降低无叶扩压器高度的方法,使末级效率提高1.8%,效果显著。通过对裂解气压缩机的末级结构进行数值模拟,发现大流量模型级中无叶扩压器的流道长度对整级性能的影响没有中、小流量模型级明显。蜗壳的方位、出口隔板倒角大小等因素对整级性能都有一定的影响。本文的研究工作在一定程度上为无叶扩压器及排气蜗壳的流场分析和结构改进提供了有建设性的意见,所得出的结论为今后的基本级的优化提供了依据。更多还原

【Abstract】 Centrifugal compressors play an important role in many fields for their special advantages such as high reliability,low volume and weight.At the same time,extensive application also means that they will consume a large amount of energy sources.In many industry fields,as the increasingly strict requirements of high load,high efficiency and some other special demands,more researches on centrifugal compressors are imperative.Because of the complex structure,previous works on centrifugal compressors mainly focused on one single part.With the development of computer technology,more and more researchers begin to pay attention to the matching of each part in order to improve the whole stage performance of the centrifugal compressor.This thesis focused on the last stages of two typical centrifugal compressors.A numerical analytic system was developed based on the commercial software Pro/Engineer and NUMECA.Several geometry models on propylene compressor with different D₄/D₂ were built and experimented numerically.Flow inside the last stage of centrifugal compressor was analyzed and the best value of D₄/D₂ was concluded.Different type volutes were combined with the same diffuser and impeller so as to find the influence between the upstream and downstream parts.According to the law of conservation of momentum torque,the internal volute with constant breadth was designed and the modification was proposed by reducing the length of vaneless diffuser.As a consequence,the efficiency of the last stage was successfully increased by 1.8%.The influence of the diffuser length on stage performance with big flow coefficient was less than the stage with small and middle flow coefficient,based on the simulation on the pyrolysis compressor.Other factors such as the volute orientation,the chamfer of the clapboard also have influence on the stage performance.The research results presented in this thesis may provide some guidelines for flow analysis and structure modifications of the volute and diffuser and the optimization of the whole stage.更多还原