I'm building a PC and I don't have an available power supply yet, so I'd
like to know if there's a way to determine which way a fan will blow. I
noticed that the fan blades are all curved. With my limited knowledge
of aerodynamics I believe the fans will blow in the direction of the
convexity of the fan blades. In other words, the radius of the
curvature will be on the side where air blows away. I wish I could
explain it in better words. Can anyone confirm this, or let me know of
a better way to determine?

~wm

wm wrote:
> I'm building a PC and I don't have an available power supply yet, so
> I'd like to know if there's a way to determine which way a fan will
> blow. I noticed that the fan blades are all curved. With my limited
> knowledge of aerodynamics I believe the fans will blow in the
> direction of the convexity of the fan blades. In other words, the
> radius of the curvature will be on the side where air blows away. I
> wish I could explain it in better words. Can anyone confirm this, or
> let me know of a better way to determine?
>
> ~wm

Yup, look on the side of the fan for a little arrow. With my limited
knowledge of archery, I have concluded that the air blows in the direction
of the arrow!

;>)

Martin


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.577 / Virus Database: 366 - Release Date: 03/02/2004

"Martin" wrote:
> wm wrote:
> > I'm building a PC and I don't have an available power supply yet, so
> > I'd like to know if there's a way to determine which way a fan will
> > blow. I noticed that the fan blades are all curved. With my limited
> > knowledge of aerodynamics I believe the fans will blow in the
> > direction of the convexity of the fan blades. In other words, the
> > radius of the curvature will be on the side where air blows away. I
> > wish I could explain it in better words. Can anyone confirm this, or
> > let me know of a better way to determine?
>
>
> Yup, look on the side of the fan for a little arrow. With my limited
> knowledge of archery, I have concluded that the air blows in the direction
> of the arrow!

Another method is to look for where the opening for the motor is; that is always faces towards
output side.

Jon

wm wrote:

> I'm building a PC and I don't have an available power supply yet, so I'd
> like to know if there's a way to determine which way a fan will blow. I
> noticed that the fan blades are all curved. With my limited knowledge
> of aerodynamics I believe the fans will blow in the direction of the
> convexity of the fan blades. In other words, the radius of the
> curvature will be on the side where air blows away. I wish I could
> explain it in better words. Can anyone confirm this, or let me know of
> a better way to determine?

Other than look at the arrow on the fan's casing?

Imagine the fan's blades as a spoon. The air flows out of the section
of the spoon that would hold the cereal.

( airflow is ->

On Tue, 03 Feb 2004 13:25:07 -0800, ric <(E-Mail Removed)> wrote:

>wm wrote:
>
>> I'm building a PC and I don't have an available power supply yet, so I'd
>> like to know if there's a way to determine which way a fan will blow. I
>> noticed that the fan blades are all curved. With my limited knowledge
>> of aerodynamics I believe the fans will blow in the direction of the
>> convexity of the fan blades. In other words, the radius of the
>> curvature will be on the side where air blows away. I wish I could
>> explain it in better words. Can anyone confirm this, or let me know of
>> a better way to determine?
>
>Other than look at the arrow on the fan's casing?
>
>Imagine the fan's blades as a spoon. The air flows out of the section
>of the spoon that would hold the cereal.
>
> ( airflow is ->
In layman's terms the airflow is out of the power supply..
Common sense says you don't want it sucking air into the case, all
that dust. So a it blows out and a vent is located somewhere on the
front?side of the tower case to allow for cross flow.

PSU suck air up into the unit's bottom fan and blow it out the back of the
case. This describes the action of 90% of the PSU's out there.

--
DaveW



"wm" <(E-Mail Removed)> wrote in message
news:cnTTb.4283$Le3.3386@okepread04...
> I'm building a PC and I don't have an available power supply yet, so I'd
> like to know if there's a way to determine which way a fan will blow. I
> noticed that the fan blades are all curved. With my limited knowledge
> of aerodynamics I believe the fans will blow in the direction of the
> convexity of the fan blades. In other words, the radius of the
> curvature will be on the side where air blows away. I wish I could
> explain it in better words. Can anyone confirm this, or let me know of
> a better way to determine?
>
> ~wm

Martin wrote:
> wm wrote:
>
>>I'm building a PC and I don't have an available power supply yet, so
>>I'd like to know if there's a way to determine which way a fan will
>>blow. I noticed that the fan blades are all curved. With my limited
>>knowledge of aerodynamics I believe the fans will blow in the
>>direction of the convexity of the fan blades. In other words, the
>>radius of the curvature will be on the side where air blows away. I
>>wish I could explain it in better words. Can anyone confirm this, or
>>let me know of a better way to determine?
>>
>>~wm
>
>
> Yup, look on the side of the fan for a little arrow. With my limited
> knowledge of archery, I have concluded that the air blows in the direction
> of the arrow!
>
> ;>)
>
> Martin
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.577 / Virus Database: 366 - Release Date: 03/02/2004
>
>

Well color me jackass! I can't believe I missed something so obvious.
And here I was trying to remember physics to figure this one out. =/
Thanks a bunch.

~wm

"ric" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)...
>
> Imagine the fan's blades as a spoon. The air flows out of the section
> of the spoon that would hold the cereal.
>
> ( airflow is ->

Thinking of ice cream rather than cereal usually gives more accurate results
for me.

wm wrote:
> Martin wrote:
>> wm wrote:
>>
>>> I'm building a PC and I don't have an available power supply yet, so
>>> I'd like to know if there's a way to determine which way a fan will
>>> blow. I noticed that the fan blades are all curved. With my
>>> limited knowledge of aerodynamics I believe the fans will blow in
>>> the direction of the convexity of the fan blades. In other words,
>>> the radius of the curvature will be on the side where air blows
>>> away. I wish I could explain it in better words. Can anyone
>>> confirm this, or let me know of a better way to determine?
>>>
>>> ~wm
>>
>>
>> Yup, look on the side of the fan for a little arrow. With my limited
>> knowledge of archery, I have concluded that the air blows in the
>> direction of the arrow!
>>
>> ;>)
>>
>> Martin
>>
>>
>> ---
>> Outgoing mail is certified Virus Free.
>> Checked by AVG anti-virus system (http://www.grisoft.com).
>> Version: 6.0.577 / Virus Database: 366 - Release Date: 03/02/2004
>>
>>
>
> Well color me jackass! I can't believe I missed something so obvious.
> And here I was trying to remember physics to figure this one out. =/
> Thanks a bunch.
>
> ~wm

If it's any consolation, I did exactly the same as you once. I had to post
to a NG to get the answer too..... (and I'm not just saying that to make you
feel better).

Martin



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.577 / Virus Database: 366 - Release Date: 03/02/2004

DaveW <(E-Mail Removed)> wrote:
| PSU suck air up into the unit's bottom fan and blow it out the back
| of the case. This describes the action of 90% of the PSU's out there.

Except for the majority of PSUs which only have one fan :-)