Numerical Simulation on Internal Flow Field of a Two-stage Variable Vane Axial Flow Fan

Numerical simulation was carried out on steady-state three-dimensional flow field in a two-state variable vane axial flow fan matched for 600MW units using Fluent software,so as to analyze the internal flow field of its first-stage and second-stage impeller and the influence of installation angle on the performance of axial flow fan.Results show that the total outlet pressure of second-stage impeller distributes alternatively in the way of high-pressure zone and sub-high-pressure zone,presenting lower symmetry than the first-stage impeller.The total and static pressure curves on pressure and suction side of both impellers' blades have similar distributions,and the static pressure on blades of second-stage impeller is larger than that in corresponding position of the first-stage impeller on both the pressure and suction surfaces.With the rise of installation angle,the total pressure rise coefficient of both impellers and the diffuser coefficient of the guide vane tend to increase,and the increasing range of coefficient for the second-stage impeller is greater than the first one,showing a superior performance of the second-stage impeller in both working and diffusion capability respectively of the first-stage impeller.