【作者】 石汇林；

【导师】 吴克启；

【作者基本信息】 华中科技大学 ， 流体机械及工程， 2006， 硕士

【摘要】 动叶可调大型轴流引风机广泛应用于300MW以上大容量火电机组。日益苛刻的能源与环境要求,近几年大型轴流风机的高效性和调节特性引起了人们的特别关注。大型轴流式引风机运行工况直接关系到锅炉以至整个机组运行的安全经济性,为提高引风机运行可靠性,须对风机内部流场结构和流动损失进行研究。目前对轴流引风机的研究主要采用实验的方法给出风机的调节性能和机械结构性能,本文采用CFD方法对其内流特性进行数值研究,阐述风机内部的某些流动细节,旨在为风机结构优化提供依据和参考。本文CFD分析使用商业软件FLUENT,采用雷诺时均的三维Navier-Stokes方程,选用标准k ?ε两方程湍流模型对大型轴流引风机分别进行了全流道和单流道数值模拟,性能计算值与实验值对比,验证了CFD计算的有效性。文中对轴流引风机整机作数值分析,着重研究不同结构配置的进气箱内部流场,探讨其内部流动损失的原因,比较几种不同结构配置的进气箱性能,计算结果为进气箱结构的优化设计提供参考。论文同时探讨了来流条件—进口预旋对叶轮内流的影响,分析不同预旋角时风机内流特性,旨在为前导叶的设计及安装提供依据。数值计算了不同叶片安装角时的风机性能,分析不同叶片安装角时风机内部流场分布,讨论了动叶可调轴流引风机的调节性能。初步探讨了动叶与导叶之间的轴向间隙对大型轴流风机性能的影响,旨在综合考虑性能和风机轴向尺寸时,选取合适的轴向间隙范围。对风机出口整流体进行数值研究,分析了扩散筒内部流动情况,比较了采用不同方案整流体时扩散筒的扩压效率和损失,进而选取性能较好的整流体。更多还原

【Abstract】 Nowadays the high efficiency and regulating characteristic of large axial fan are attended especially, because the demands of energy sources and environment are rigorous increasingly, and adjustable rotor blade axial induced draft fan is used widely in large power plant which capacity is more than 300MW. The work condition of large axial fan directly influences the security and economical efficiency of boiler up to whole power plant. The internal flow structure and flow loss in axial fan has been researched in order to get higher work reliability. The research of axial induced draft fan is focused on the regulating characteristic and mechanism structure performance used experiment method. The numerical research is carried out on three dimensional internal flow field of fan used CFD method. Some flow details are showed and the structure optimization design of fan can be suggested from this paper.In this thesis, CFD analysis using FLUENT commercial software based on solving Reynolds averaged Navier-Stokes equations coupled with K-εturbulence model has been used to study the internal flow field of large axial induced draft fan with whole and single flow passage. The numerical results are compared with the experimental data, which validate the precision of the numerical simulation.Numerical analysis with the whole flow passage has been studied between different configuration on inlet box internal flow of axial induced draft fan. Numerical simulation results reveal the reason of the loss in inlet box. Performance of different configuration inlet box is compared. The structure optimization design of inlet box can be suggested from the paragraph.In addition, the influence of impeller’s internal flow field from inlet prerotation flow conditions is researched. Internal flow characteristic of different prerotation angle is compared, which can be used in the design and setting of inlet guide vanes. Performance and internal flow field distribution of various blade stagger angle of axial fan is computed. Regulating characteristic of adjustable rotor blade axial induced draft fan is discussed. The influence of large axial fan’s performance from axial clearance between rotor and stator is analyzed simply, which can be used to select appropriate axial clearance range when performance and axial size are considered synthetically.The performance of outlet rectifier object is investigated using numerical simulation. Internal flow field of diffuser is analyzed, diffuser efficiency and flow loss of diffuser between various rectifier object are compared, and than selecting preferable rectifier object.更多还原