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PC Fan of the Future?
baptiste writes "While we marvel at the latest CPU release or new motherboard chipset, we still put the same old fans in the neon lit cases and then complain that it is too loud. Well, maybe someone has finally come up with the next generation PC fan. Y.S. Tech has announced a new fan which is driven at the blade tips by a magnetic motor in the housing. Without the motor in the middle they claim a 30% airflow improvement meaning, potenitally, you could get the same airflow of today's fans at a lower RPM meaning less noise. They also claim the fan tips result in the bulk of fan noise. In this design they are sort of enclosed, reducing noise further. There is also a PDF datasheet available."
The point is that airflow increases with rpm times the SQUARE of diameter, which means if you make the fan 2x as big, you can make it 4x slower. The original NeXT boxes used a big, slow-turning fan to keep noise down, and it was quite effective. PC's usually use 3 inch fans but with some case mods could probably be set up with 5 inch fans, which for the same airflow could quiet things down a lot.
Add to that a hard disk with a fluid bearing spindle motor (pdf) and you've got a rather civilized box on your desk. I'm using one of these drives now (Travelstar 30GN) and the difference between it and an old drive is wonderful. The quietness is like getting rid of a toothache.
Almost all Apples SILENT (Apple 2, Apple 3, Mac+, IIfx, iMac, Cube, iBook, Newton, etc.
That is almost the main engineering case design criteria and why so many fussy demanding people like artists, musicians, scientists (chemists, biologists) and even programmers continue to support apple products.
PeeCees are like load aircraft carriers or at least Vaccuum cleaners comapred to the majority of the most popular selling Apple Computers.
Did you know the Apple 2 had NO FAN at all?
Same with the Mac Plus... no FAN at all.
and most all the products since the IIfx have a variable speed fan that increases rotation only if truly needed... like the Wallstreet G3 laptops.
When Steve jobs created the NeXT workstation he designed every cable to be one long 10 foot single cable so that the machine (almost quiet) could be hidden insode a closet or put very far from your monitor! He hates noise of all kinds.
Hurray for quiet or semi-quiet hardware.
There may be good economic reasons to put the motor parts on the OD of the fan and that is good. But, all statements about the air flow and cooling capabilities are pure PR.
First, the velocity of the blades near the hub are too slow to put work into the air and therefore the air tends to leak backwards near the hub. This is why putting the motor in the hub area does not degrade fan performance.
Second, while the fastest parts of the fan (the blade tips) make most of the fan noise, changing their shape does the most to reduce the noise. The noise has nothing to do with the "motor parts" that reside in the blade tips in this design.
Third, the pressure generated by the fan is solely dependant on the fan design and has nothing to do with how the fan is powered.
Fourth, of course the torque is more effective at a larger radius, but this has nothing to do with efficiency.
Fifth, any increase in air flow has to do with the shape of the blades and the speed of the fan and can probably be improved a somewhat by blocking the hub a little.
Sixth, I do not see how the fan improves the efficiency of cooling anything. Increased air flow will cool anything better, according to how much horsepower do you want to put into your fan. And, it matters a whole lot where the parts to be cooled are in relation to the exit air stream, etc.etc.etc. Nothing but PR here.