| Cross-flow fans are widely used in low-pressure ventilation devices such as household air conditioners because of their small size,uniform air supply and low noise.The research on its air supply and noise performance has become a hotspot in the study of cross-flow fans.In this paper,stationary channel profile of cross-flow fan is research object.Using genetic algorithm combined with CFD numerical calculation,the rearwall,tongue and stationary channel profile are optimized.The influence of different stationary channel profile on the aero-acoustic performance and internal flow field of the fan was studied.The formation reason of eddy current in the downstream of the rearwall clearance of the cross-flow fan is studied and the influence of flow rate on it is analyzed.The results show that with the decrease of flow rate,the vortex area will shift to the upstream direction.The influence of rearwall clearance circumferential position is studied.The results show that when the circumferential position Angle of rearwall clearance decreases,the fan static pressure increases,the efficiency first rises and then falls,and the downstream eddy current area of rearwall clearance expands.Then the influence of volute profile,volute tongue profile and static runner profile optimization on fan aerodynamic performance is studied,it was found that the circumferential position Angle of rearwall clearance decreased after optimization,the downstream profile of rearwall clearance was convex,the downstream profile below the impeller contracted inward,and the static pressure of the fan increased significantly.The downstream vortex zone of rearwall clearance expands and moves downstream,and the fan efficiency decreases.After optimization,the upstream profile of the tongue was approximately a straight line with the inlet flow guide,and the eddy current area in the upstream of the tongue gap was reduced.Compared with the prototype,the circumferential position Angle of the tongue clearance decreased,the space of the impeller on the outlet side increased,and the work done by impeller increased as the eccentric vortex enhanced,so the flow velocity in the main flow area increased,the static pressure of the fan increased,and the efficiency decreased.The tongue profile of overall optimized stationary channel is between the prototype and the single optimized tongue profile.The first half rearwall profile of the overall optimized stationary channel is similar to the single optimized rearwall profile,but the downstream rearwall profile expands outward and the space between the rearwall and the impeller increases.The eccentricity vortex of overall optimized stationary channel is significantly shifted away from the tongue,so that the static pressure of the fan increases more and the efficiency decreases less.The acoustic characteristics of cross-flow fans with different static flow channels were studied,and the results showed that the fundamental frequency and harmonic peak of the overall optimized stationary channel were significantly reduced,and the noise reduction was mainly caused by the eccentric vortex away from the tongue.Genetic algorithm is adopted to optimize the overall profile of the stationary channel,which can maximize the interaction between the rearwall and the tongue to improve the internal flow of the fan,improve the static pressure of the fan and reduce the aerodynamic noise of the fan. |
PDF Full Text Request