Study Of The Whole Flow Field In The Axial Fan Based On The Numerical Simulation Of Unsteady Turbulent Flow

An unsteady numerical simulation was performed in this paper for the flow in a two-stage axial flow fan, which was designed in one-dimensional method. In the simulation, the whole inner flow field, which was from the inlet of the collector to the outlet of the diffuser, was taken as the computational domain.At the beginning, the geometry model of the computational domain was built, and the whole domain was discretized with the unstructured tetrahedron grid elements. In the unsteady numerical simulation the moving mesh method was adopted, and a couple of rotator-stator interfaces was used to transfer data between the rotating field and the rest field. Then, The governing equations set was deduced, and the RNG k-εtwo-equation model was used to describe the 3-D unsteady turbulent flow in the fan. Besides, the governing equations were discretized in both the space and the time domain. Where the second-order differencing scheme was used to discretize the diffusive term, the QUICK scheme was used to treat the convective term, and the transient term was disposed of with the implicit second-order scheme.Then, the simulation was did on the boundary conditions that: At the inlet of the computational domain the total pressure was preset, while at the outlet the backing pressure was specified, and on all the walls the No Slip Shear Condition was adopted. When the governing equations for the unsteady flow were solved, the Time Marching Method and the SIMPLE algorithm were employed, and to boost the stability of the unsteady numerical computation, at first, a steady simulation was did on the same model, and then the result of the steady simulation was used as the initial condition of the unsteady simulation.At last, the result of the unsteady numerical simulation was analyzed, and the characteristics of the whole inner flow field were predicted through the result of several typical cross sections. Also, the pressure impulsive motions at the front edge of the blade were analyzed in the fast Fourier transform (FFT) method. The data in this dissertation could provide references for the inner flow optimization of the axial-flow fan.