Quote:
Originally Posted by mikels
OEM fans are not typically rated in CFM. 850W is simply (volts x amps).
Obviously, that is not enough to design to for cooling requirements, so a volume flow rate vs. pressure drop is required - this is where many fans fall short as they are rated in CFM @ 0 (zero) pressure drop - which is not how you are using them (And some have dramatic loss in flow with pressure drop).
The SRX turbo fan flows:
~1.0 m^3/sec @ 300 Pa pressure drop (2119 CFM @ 1.2"H2O)
~1.5 m^3/sec @ 225 Pa pressure drop (3178 CFM @ 0.9"H2O)
So pressure decrease of 25% results in flow increase of 50%. Now you can see why flow curve (mass flow vs. pressure drop) is what you are really looking for in fan specifications.
If you extrapolate flow curve for SRX turbo fan, flow @ 0 pressure drop is on the order of ~2.5 M^3/sec (5300 CFM). (not 100% accurate as flow rates become non-linear at very high and low pressure drops)
You really need to know what the pressure drop is through your cores to determine flow rate of fans (that combined with heat exchanger efficiency will give you kW heat rejection).
BTW- Modern high-efficiency cores are WAY more efficient than old-school designs - so not as simple as looking at core thickness, size, etc..
Dave
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Thanks Dave, this data is literally exactly what I was hoping for, but being the internet, was not expecting it!
I was also asking for core thickness as a reference for the rough resistance that the fan would be working against statically (not including added resistance of IC in front). Obviously dynamically there are added factors under speed such as ram air effect on some of the frontal area as well as pressure differential across the "cooling stack" due to chin spoiler, etc... just looking for a rough idea of if it's a 2", 3.5", or 17.623578" thick core.
Cheers,
Joe