Analyze the phenomenon reason of cross flow fan produce against the wind.

Analyze the phenomenon reason of  cross flow fan produce against the wind.

In the process of running cross flow fan can appear the phenomenon against the wind,so what is the cause of this phenomenon? Below simple  analysis for your reference.

Cross flow fan occur air flow-back phenomenon mainly because of the improper design, namely mutual exchange of inlet & outlet.

Asymmetry of the external boundary (including the asymmetric with impeller clearance) is the basic conditions let the cross flow fan enable the fluid to make a steady flow along with the certain direction .

When the impeller turns with the fluid,if flow field only have one linear boundary, then, near the border will form a spiral following the located downstream of impeller rotation minimum clearance direction  and around the impeller place. Rotation direction of cross flow fan is same as the impeller turn direction, the strength of the vortex depends largely on the running speed of the impeller and boundary conditions.The impeller flow field inside and outside primary under the control of this vortex.

If there have multiple boundary, the flow field depends on the comprehensive effect around the border.Vortex appears around the border near the poor flow resistance, and only one spiral.For cross flow fan , in order to make its faded to work normally and not against the wind, gouge out compared with the other boundary, vortex tongue place should have a larger poor flow resistance.