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Curved fan blade direction
richardm6994 - 20/7/13 at 12:37 PM

I have a push / pull fan.

When the fan is spinning, which direction should the curved blade be pointing?

I think it is the tips of the blades that should be trailing and the curve leads but I just wanna check

gremlin1234 - 20/7/13 at 12:44 PM

they usually have an arrow on the hub showing intended direction

rdodger - 20/7/13 at 12:52 PM

Curved blade fans should turn with their tip leading.

In terms of performance, straight blade fans are better. Curved blades reduce noise.

Interesting explanation

http://www.daviescraig.com.au/Straight_vs__Curved_Fan_Blades___Dispelling_the_Myth-news.aspx


[Edited on 20/7/13 by rdodger]

richardm6994 - 20/7/13 at 01:30 PM

quote:
Originally posted by rdodger
Curved blade fans should turn with their tip leading.

In terms of performance, straight blade fans are better. Curved blades reduce noise.

Interesting explanation

http://www.daviescraig.com.au/Straight_vs__Curved_Fan_Blades___Dispelling_the_Myth-news.aspx


[Edited on 20/7/13 by rdodger]


So as it rotates, the tips of the blades are ahead of the curve? Are you certain this is correct?

I'm in the garage now and testing both and it's hard to tell the difference but the tips behind the curve seems slightly better.

I'm so confused!!!

dave r - 20/7/13 at 03:03 PM

all the fans i have tried like that, there is a vast difference between right way and wrong way

rdodger - 20/7/13 at 05:41 PM

Yes basically it looks wrong but the tip should curve in the direction of the rotation.

The one here would rotate clockwise.

http://www.quillertriumph.co.uk/Quiller/Parts/accessories/coolingfans.htm

[Edited on 20/7/13 by rdodger]

sebastiaan - 20/7/13 at 09:49 PM

Sorry, but that is wrong. The blade tips should be trailing on high skew (= "banana" type blades. Like so (sorry about the large pic):


rdodger - 20/7/13 at 10:17 PM

That's really odd. I had curved fans on my last kit and the manufacturer instructed me to run them tip first.

Perhaps different ones run in different directions?

02GF74 - 24/7/13 at 11:00 PM

surely it is the angle of the blades that matters - it cojld be possible the angle on those 2 curved blade fans are different?

I mean if the fan blades were flat, it would make no difference whcih way round they turned ~????

sideways view of blade: / ->> pushes air downwards

adithorp - 25/7/13 at 06:39 AM

quote:
Originally posted by 02GF74
surely it is the angle of the blades that matters - it cojld be possible the angle on those 2 curved blade fans are different?

I mean if the fan blades were flat, it would make no difference whcih way round they turned ~????

sideways view of blade: / ->> pushes air downwards


Think this is correct. The curveed blades rotate differently from different makers.

Look at the blade shape. They'll be curved in cross section. Leading edge will be the shallower angle (almost 90' to the air-flow) and the angle increase towards the trailing edge.

britishtrident - 25/7/13 at 07:36 AM

As adithrop says the is the shape of the cross-section of the blade that matters, easy way to work it out at is the leading edge of the blade should smoothly scoop up stationary air. The fan blade scoops up the stationary air and should smoothly accelerate it, so leading edge of the blade has a shallow angle and the trialling edge a more "coarse" angle almost parallel to the direction the air is flowing in.

[Edited on 25/7/13 by britishtrident]