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What will be the effect of series connection of two fans on static pressure of air? Answered

I have bought two similar  axial fan blades similar in each respect pitch,size,material,angle of attack etc below is the image.I have a powerful 300W electric motor.I want to attach{weld} both of these blades with the shaft of the same motor in series one above the another on the same motor shaft this would ensure that both the blades rotate with same RPM ,of course they would be separated by some distance i know that series connection of fans would increase the static pressure of air,but what confuses me a lot is that how the guide vanes{wings} of both the blades be aligned with respect to each other for maximum static pressure should the wings of both the blades synchronize with each other i-e clocked at the same rate or should they be at different positions with respect to each other.I have searched every forum but nothing fould.You people are my last hope.



Best Answer 3 years ago

The air temperature, pressure (density), RPM and spacing of the fans will determine the preferred axial alignment of the blades for best pressure...

Bare in min mind the best volumetric air flow will be a different axial alignment !

What do you think if both these fans spinning at the same RPM separated by a little distance so that there wings are aligned the same way always {they synchronize with each other clocked at the same rate} what would be the effect of airflow then will the static pressure increase.I only need the static pressure to increase not the volume of air!.They say static pressure is additive for fans in series

Having worked with bladed fans I discovered the pressure flow is Radial to the axis, so I do not believe aligning the wings to be as helpful as staggering them.


3 years ago

I believe that when you add extra fan blades what you end up doing is creating an inefficient auger. In addition to pushing the air forward you add a rotation to the air so you are creating a vortex. A lot of your extra energy goes into spinning the air rather than pushing it. This would be the case if you had multiple blades The air rotation would eventually equal the rotation of blades. With only 2 blades the effect would be much less but you would still be loosing efficiency. At least that is how I understand it works.