A Axial-Centrifugal Fan Cfd Simulation And Opitimal Designe

Axial-centrifugal fan is the machine which depends on the input mechanical engineering used to improve gas pressure and also discharge gas. It is the passive fluid machinery, which is widely used in discharging dust and cooling of factory, mine, tunnel, cooling tower, vehicle, vessel, buildings. The property of axial-centrifugal fan is measured through total pressure by the exit and the efficiency. The research of axial-centrifugal before mainly employed the combination of theoretical analysis and experiments. However, recently, the development of techniques of Computational Fluid Dynamics and the population of commercial CFD software, which have made it possible that the inner fluid field and property have been researched in the means of the numerical simulation and fluid visualization through the computer.The thesis used the ANSYS CFX10.0to simulate the characteristics in the working condition of designed speed for THTF4.5centrifugal fan. The main content includes that: First, in order to guarantee the high precision of CFD calculation, the three-dimensional modeling software UG was used to build geometry model of the axial-centrifugal fan’s inner flow field and the preprocessing software ICEM CFD was used to divide the fan’s flow fluid into hexahedral grid of H style. Second, the K-epsilon turbulence model and the Rotating Reference Frame rotational coordinate system were used to solve the total inner flow field. The flow fields of the centrifugal impeller, stator, plate and backflow gap were analyzed and researched. The result was that the flow field of impeller root and middle part had the situation of airflow separated, which was caused by the unreasonable structure. Third, the thesis put forward two better structures from the angle of super plate and annular clapboard in the basis of the original structure. Then the numerical simulation calculation of two optimal structures was also studied based on flow field analysis and the previous engineering experience, which was used to the utter pressure and efficiency. The result of CFD calculation demonstrated that the two optimal structures were better, and the second had larger charge than the first.Through the comparison with simulation results and test data, the results of numerical simulation of the centrifugal fan were satisfied. The difference of flow, pressure ratio, efficiency and other important parameters was within3%. The numerical simulation results of the two optimization schemes were better than the original design scheme significantly.