| 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.
|
PDF Full Text Request