| [GMCnet] John Biwersi's new direct replacement fan [message #268935] |
Mon, 05 January 2015 19:57  |
Advanced Concept Ener
Messages: 112
Registered: December 2014
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The HP required to drive a fan is proportional to the cube of the flow and the square of of differential pressure produced by the fan. That means if the fan flow goes up by two the HP goes up by eight. If you flow more air over a fixed area of resistance the differential pressure drop across the area goes up by the square. Don’t be trying to save HP by small increases in fan efficiency. The fan noise is caused by air velocity passing through a restriction or the air backing up in the fan because it can’t produce enough pressure to move the air out of the blade. If you have 10 blades instead of 7 chances are the velocity across the blade is lower and probably more quiet. Drag on a smooth sheet metal blade probably won’t make that much difference from a smoother plastic blade in our application at our velocities. The HP to be saved is in the clutch and fan speed. The thermostat limits the water flow to reach setpoint temperature of the stat. Trying to control fan speed from radiator water temperature means you are fighting the thermostat. You would probably want to control the oil temperature (assuming no bypass) back to the engine to control fan speed and let the thermostat take care of the water temp. The idea of using an electric clutch and using pulse width modulation to control oil temperature sounds very do-able and very interesting. You can buy an electronic controller (with remote setpoint dial) that senses temperature and outputs pulse width modulation for the fan clutch for about $12.00. (check Ebay) So who has the part number for the electric clutch? I think I also found a clutch that uses a remote strap-on sensor to control it. No electronics and no complications. If you can provide the right amount of air for only the cooling you need than you have optimized the process and minimized HP.
Jon Darcy
aces4nrg@gmail.com
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #268968 is a reply to message #268935] |
Tue, 06 January 2015 07:36  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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This is a response to Jon Darcy's post of 05 January 2015
Jon,
You got the engineering correct with the cube and square relations, but what I believe you missed was the difference that the blade section can make. That relationship holds for the same fan in different speed/load cases. It breaks down with different fan designs and is really lost when radical changes like true section, twisted and tapered blades are introduced.
If I still had access to a tunnel, I would love to run both fans and get some real numbers, but - alas - that is not likely. I can assure you that as I remember and look at old reports, that what we were able to do with NACA blade sections and careful manufacturing was to increase air flow through a system by a significant amount (one case I still have the report for was 25%) and the same shaft speed and about 10% lower torque and remarkably lower (not measured) noise. One should remember (as Harriers and helicopters will always server to remind us) that noise is also generated by using horsepower. Stamped sheet metal fans are very good for first cost and also at making noise, but that is the limit of the advantage that they have.
I did work for Hayes Cooling until they augered in, and the difference between a stamped sheet metal fan and a molded blade can only be discounted by the purchasing group.
Matt - the itinerant engineer
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #268998 is a reply to message #268968] |
Tue, 06 January 2015 10:46 |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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Somebody throw out a rope for these guys, they are floating off! Wow Jon
and Matt, I had no idea you could string a thought like that out -- man,
I'm impressed! So, do we like these new fans is what I wanna knw...
Jim Bounds
------------------------
On Tue, Jan 6, 2015 at 8:36 AM, Matt Colie wrote:
> This is a response to Jon Darcy's post of 05 January 2015
>
> Jon,
>
> You got the engineering correct with the cube and square relations, but
> what I believe you missed was the difference that the blade section can
> make.
> That relationship holds for the same fan in different speed/load cases.
> It breaks down with different fan designs and is really lost when radical
> changes like true section, twisted and tapered blades are introduced.
>
> If I still had access to a tunnel, I would love to run both fans and get
> some real numbers, but - alas - that is not likely. I can assure you that
> as I remember and look at old reports, that what we were able to do with
> NACA blade sections and careful manufacturing was to increase air flow
> through a system by a significant amount (one case I still have the report
> for was 25%) and the same shaft speed and about 10% lower torque and
> remarkably lower (not measured) noise. One should remember (as Harriers
> and helicopters will always server to remind us) that noise is also
> generated
> by using horsepower. Stamped sheet metal fans are very good for first
> cost and also at making noise, but that is the limit of the advantage that
> they
> have.
>
> I did work for Hayes Cooling until they augered in, and the difference
> between a stamped sheet metal fan and a molded blade can only be discounted
> by
> the purchasing group.
>
> Matt - the itinerant engineer
> --
> Matt & Mary Colie - Members GMCMI, GMCES
> '73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #268999 is a reply to message #268998] |
Tue, 06 January 2015 10:55 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Jim at the Co-op wrote on Tue, 06 January 2015 10:46... So, do we like these new fans is what I wanna know...
Jim Bounds
Jim, you are welcome to come over to the LazyDays rally in a couple weeks and take a look/listen at mine. I'll have a good drive under my belt by the time we get there and have a more definitive opinion. More importantly, the wife's ears are much more attuned to noise than mine.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
[Updated on: Tue, 06 January 2015 10:56] Report message to a moderator |
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #269001 is a reply to message #268935] |
Tue, 06 January 2015 11:00 |
rcjordan
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
Karma: 1
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JimB's already slated to install a couple ...he just doesn't know it yet.
Meanwhile, you sold out John's stock of fans, Kerry. New batch is to arrive soon.
SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #269019 is a reply to message #268935] |
Tue, 06 January 2015 12:41 |
rcjordan
Messages: 1913
Registered: October 2012
Location: Elizabeth City, North Car...
Karma: 1
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Senior Member |
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>it will be an improvement
Somewhere today, you posted about "reading a thread by people whose opinions you've come to respect." The same goes for the fans blades.
TLDR: Just do it.
SOLD 77 Royale Coachmen Side Dry Bath
76 Birchaven Coachmen Side Wet Bath
76 Eleganza
Elizabeth City, NC
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #269129 is a reply to message #268999] |
Wed, 07 January 2015 13:15 |
Chris Tyler
Messages: 458
Registered: September 2013
Location: Odessa FL
Karma: 7
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Senior Member |
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kerry pinkerton wrote on Tue, 06 January 2015 10:55Jim at the Co-op wrote on Tue, 06 January 2015 10:46... So, do we like these new fans is what I wanna know...
Jim Bounds
Jim, you are welcome to come over to the LazyDays rally in a couple weeks and take a look/listen at mine. I'll have a good drive under my belt by the time we get there and have a more definitive opinion. More importantly, the wife's ears are much more attuned to noise than mine.
any info on this Lazy Days Rally? It s in my backyard [basically] and I used toi be parts Mgr for them many moons ago
Just had Gall Bladder surgery...hopefully will be back up to speed. Would be nice to meet some people in person!
76 Glenbrook
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| Re: [GMCnet] John Biwersi's new direct replacement fan [message #269906 is a reply to message #268968] |
Sat, 17 January 2015 21:34 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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Matt Colie wrote on Tue, 06 January 2015 06:36This is a response to Jon Darcy's post of 05 January 2015
Jon,
You got the engineering correct with the cube and square relations, but what I believe you missed was the difference that the blade section can make. That relationship holds for the same fan in different speed/load cases. It breaks down with different fan designs and is really lost when radical changes like true section, twisted and tapered blades are introduced.
If I still had access to a tunnel, I would love to run both fans and get some real numbers, but - alas - that is not likely. I can assure you that as I remember and look at old reports, that what we were able to do with NACA blade sections and careful manufacturing was to increase air flow through a system by a significant amount (one case I still have the report for was 25%) and the same shaft speed and about 10% lower torque and remarkably lower (not measured) noise. One should remember (as Harriers and helicopters will always server to remind us) that noise is also generated by using horsepower. Stamped sheet metal fans are very good for first cost and also at making noise, but that is the limit of the advantage that they have.
I did work for Hayes Cooling until they augered in, and the difference between a stamped sheet metal fan and a molded blade can only be discounted by the purchasing group.
Matt - the itinerant engineer
When I was still in charge of trucks at GM, computer simulation of flow and noise characteristics had progressed to the point that the usual tradeoffs were no longer valid. We were able to match fans to each engine combo that outcooled and yet were more quiet than the old compromized designs of the 70's through 90's. This science has progressed to the point that you need a dedicated specialist who makes a career out of this. For us it will only come down to trial and error and hopefully we will stumble across something that is better than what we already have.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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