Effect of inlet guide vanes on the performance of small axial flow fan

Effects of the inlet guide vanes on the static characteristics,aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work.The inlet guide vanes with different outlet angle are designed,which are mounted on the casing and located at the upstream of the impeller of the prototype fan.Both steady and unsteady flow simulations are performed.The steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model,while the unsteady flow is computed with large eddy simulation.According to the theoretical analysis,the inlet guide vanes with outlet angle of 60° are regarded as the optimal inlet guide vanes.The static characteristic experiment is carried out in a standard test rig and the aerodynamic noise is tested in a semi-anechoic room.Then,performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan.The results show that there is reasonable agreement between the simulation results and the experimental data.It is found that the static characteristics of small axial flow fan is improved obviously after installing the optimal inlet guide vanes.Meanwhile,the optimal inlet guide vanes have effect on reducing noise at the near field,but have little effect on the noise at the far field.