Dyson Announces Blade-less Fan, Explains Principle
The Japanese unit of Dyson Ltd announced a new electric fan, "Dyson Air Multiplier," Oct 16, 2009, in Tokyo.
The electric fan looks like a cylindrical column topped with a ring. At the first glance, I thought it has no fan. But there actually is a fan inside its body.
The Air Multiplier uses the fan to blow air into the ring, which is hollow inside. Then, the air comes from a narrow opening of the ring. Finally, 15 times as much air as is sent by the fan can be blown from a large area because of a viscous shear flow.
"When examining a hand dryer, we found that the amount of airflow increases by sending air at high speed because surrounding air is sucked in," said Dyson Chairman James Dyson. "And we came up with the idea of making an electric fan based on the same principle."
The mechanism of the Air Multiplier is as follows. The fan inside the body blows air at up to 20L/s into the hollow ring, whose cross-sectional shape looks like an aircraft wing. The air blown from an about 1.3mm gap that is found near the tip of the wing (inner side) flows along the surface of the wing at high speed, making the air pressure in its periphery negative. Therefore, surrounding air is sucked in.
"It is the same principle that provides lifting power to an aircraft," Dyson said.
To evenly send air into the ring, the nine blades of the fan are positioned at irregular intervals. Probably, it accelerates the speed in the circumferential direction in the ring so that air runs through the ring.
Dyson stressed three advantages of the new electric fan. First, it can evenly blow air unlike traditional electric fans. Second, it does not pose a risk of hurting human fingers. Third, it is very easy to do maintenance on the electric fan.
The maximum power consumption is 40W. The quantity of airflow can be steplessly adjusted. The Air Multiplier comes in two sizes, 25 and 30cm, and the two models weigh about 1.7 and 1.8kg, respectively.
The electric fan has a function to automatically move its head through an angle of 90°. And its elevation angle can be adjusted by up to 10°.
The expected prices of the 25 and 30cm models are ¥37,000 (approx US$408) and 39,000, respectively. Dyson Ltd will launch the Air Multiplier first in the southern hemisphere, where summer is coming. In Japan, it will be sold mainly at design shops at first and debut at mass merchandisers after the spring of 2010.