Sharkoon released the latest fan in its Silent Eagle "golf ball" series.
Wednesday Sharkoon revealed the 140-mm Silent Eagle 800 fan, the latest addition to its "Silent Eagle" case fan series. What makes this particular series unique is that the rotor blades have the surface texture of a golf ball. Although the fan certainly won't help with your golf swing, the small, round dimples are said to increase the amount of airflow by reducing drag. [as proven by The Mythbusters--Ed.]
"The Sharkoon Silent Eagle 800 rotates at 800 rpm, moving 93.85 cubic meters of air per hour while at a noise level of 12.4 decibels," the company said in a press release. "The power usage is rated at 0.1 amps and 12 volts. The white propeller and black frame case fan rotates in a rugged metal bearing and weighs 162 grams."
The company said that the fan can be connected to the power supply or motherboard. Also included with the fan is a 3pin/4pin adapter cable, a 3pin connector cable protected by a rubber hose, and a separate cable for monitoring the number of revolutions. To help with the noise reduction, four fan screws and rubber bolts are also supplied.
The Silent Eagle 800 is one of many models offered in the Silent Eagle series. Other than this 140-mm version, consumers can also purchase an illuminated LED model or the SE version which includes a modular cable system.
You're confusing up profile drag and lift-induced drag. Wikipedia will be able to explain them better than me, but the basic concept is that threre are two primary kinds of drag on a wing/propeller shaped object like a fan: Profile drag is the smaller of the two. It arises because you're pushing the blades through the air and overcoming the friction between the air and the blade's surface. You'd get profile drag even if the blades were flat and weren't pushing any air.
Lift-induced drag is caused by the blades "pushing" the air. The greater the angle of attack of the blades, the more air they push, and the higher the lift-induced drag. So if the blades were flat, you'd get zero lift induced drag (but still get profile drag), but in an actual fan with the blades angled, you'd get both profile drag and lift-induced drag (which is the larger of the two).
By adding dimples, you're not increasing air flow "because you are increasing the resistance", but rather the dimples decrease profile drag (because like a golf ball, the dimples make the air flow turbulent instead of laminar, so you reduce air resistance). The fact that resistance is reduced (not increased) was written in the last line of the first paragraph of the article. My guess is that lift-induced drag remains unchanged by the dimples. So there you go you'll get the same amount of airflow but need a less powerful motor to overcome the combined drag, leading to quieter running.
55 CFM. typical of 140mm fans at 800rpm. not too impressive. but quiet.