Icepak FAQ: How to model a Radial outlet blower?

How to model a Radial outlet (blower)?

The radial blower can be simulated by placing a fan in front of a plate. The impingement on the plate will cause the flow to go
radially outward in a direction perpendicular to that of the incoming flow.
The key lies in appropriately correcting the vendor provided blower curve to account for the losses inside the blower which are
accounted in the vendor curve. If you use the same blower curve for the fan, the flow requires additional pressure to turn inside the
blower. Since this pressure is already accounted for in the vendor curve, we need to correct the blower curve before assigning it to
the fan object in Icepak. Therefore for any fan flow rate ...

DP(Fan) = DP(vendor) + Pressure drop required to turn.

Since turning is a momentum change we can expect ...

DP (turn) = 1/2 * Ro * v^2 * K
Ro density of fluid
v inlet velocity at the fan
K is a pressure drop factor depending on blower geometry.

Thus we only need, K to correct the blower curve. So how to determine K?
Please see attached model (model is archived in ~bugs/icepak/solutions/solutionID). The solution domain in this model is of the size of the blower. The outlets are made of openings at 0.0
gauge pressure. The inlet is an opening with fixed (typical) velocity. After running this model, the total pressure drop required can
be determined. This is the pressure drop associated with the turn. Therefore K can be determined by substituting in ...

Dp(turn) = 1/2 * Ro * v^2 * K

For the attached model K turns out to be about 2.
Using this value of K regenerate corrected blower curve from vendor curve and use it for the fan.

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