How the Dyson Bladeless Fan Works

In October 2009, James Dyson's consumer electronics company, famous for its line of vacuum cleaners, introduced a new device to the market called the Dyson Air Multiplier. The Air Multiplier was a fan with an unusual characteristic: no visible blades. It appeared to be just a shallow circular tube mounted on a pedestal.

Dyson has since expanded its family of air treatment products, which use the same bladeless fan technology and now include air purifying abilities. Some of them also work as humidifiers for dry rooms, and some work as both heaters and fans that move air.

But just looking at these devices, you wouldn't expect to feel a warm or cool breeze coming from them. There are no moving parts in sight. But when they're turned on, you feel blowing air. So how do they work? How can an open circle push air without fan blades?

As you might imagine, there are a few scientific principles at play here. There's also an electronic element. While the tube doesn't have any blades inside it, the pedestal of the fan contains a brushless electric motor that takes in air and feeds it into the circular tube. Air flows along the inside of the device until it reaches a slit inside the tube. This provides the basic airflow that creates the breeze you feel if you're in front of the fan.

According to Dyson, the breeze generated by these devices are more consistent and steadier than one from a standard fan with blades. Since there are no rotating blades, the breeze from the fan doesn't buffet you with short gusts of air.

What's the secret behind the technology?

Calling a Dyson Air Multiplier a fan without blades is perhaps a touch misleading. They do have blades; you just can't see them because they're hidden inside the pedestals. A motor rotates nine asymmetrically aligned blades to pull air into the device. According to Dyson, the newest iterations can project more than 77 gallons of air per second for cooling airflow.

The air flow is diverted through the back of the machine. But how does the fan multiply the amount of air coming into the pedestal of the device?

It boils down to physics. While it's true that the atmosphere is gaseous, gases obey the physical laws of fluid dynamics. As air flows through the slits in the circular tube and out through the front of the fan, air behind the fan is drawn through the tube as well. This is called inducement. The flowing air pushed by the motor induces the air behind the fan to follow.

Air surrounding the edges of the fan will also begin to flow in the direction of the breeze. This process is called entrainment. Through inducement and entrainment, Dyson claims its fans increase the output of airflow by 15 times the amount it takes in through the pedestal's motor.

Yet there's one problem that Dyson didn't quite overcome with its unique fan. Next you'll see why Dyson changed the design of its Air Multiplier when it came time to make a second version.

Despite its cutting-edge concept, the original Dyson Air Multiplier did have one notable flaw. It wasn't really very quiet. Dyson took note and decided to revamp the second generation of its fan.

Doing so required a steep investment by the company. Dyson dumped more than $60 million into research and assigned 65 engineers to the project. Together, they created 640 prototypes and filed hundreds of patents, tweaking each design a little more, to investigate the movement of air inside their funky fan.

As you can imagine, part of the noise problem originated from turbulence. The original Air Multiplier sucked air into its base, where it bounced around willy-nilly, creating chaos ... and noise. To pinpoint this noise, researchers placed the fan in a soundproof chamber with 10 microphones listening for every whir and buzz.

Then they built translucent prototypes and passed ultraviolet paint and smoke through the device. High-speed cameras provided frame-by-frame playback, offering visual clues to where air was bunching up and causing a ruckus.

Dyson's engineers addressed the turbulence problems by integrating Helmholtz cavities into the fan's base. If you've ever held a seashell to your ear or blown across the top of a glass bottle, you've experienced the effect of these cavities, in which sound bounces and skids across a hard surface.

Helmholtz cavities make noise, of course. Figure out exactly how these cavities work, and then you can control that noise. By adding Helmholtz cavities of sorts into the base of the Air Multiplier, engineers increased air pressure, and ultimately these cavities began to work as silencers.

Car manufacturers are very familiar with the principles of Helmholtz cavities. They manipulate them to their advantage when quieting exhaust systems. In the case of the Air Multiplier, engineers basically tuned the cavities to specifically mute sounds in the range of 1,000 Hertz, which humans tend to find especially aggravating.

Their efforts (and those heaping mountains of research cash) paid off. According to Dyson, the second-generation fan was 75 percent quieter than its predecessor. And because air moved more smoothly and efficiently through the entire Air Multiplier, Dyson was able to scale back on the motor. They say the newer motor required 40 percent less power.

For its quietness, the Noise Abatement Society awarded the second-generation Air Multiplier with a Quiet Mark award in 2014. The award goes to products that clamp down on unnecessary noise pollution.

Dyson has now expanded what the Air Multiplier can do far beyond merely blowing cool air. The Dyson Cool is a fan that stays true to its Air Multiplier roots. But new models also have HEPA filters in the base that, according to the company, create 50 percent cleaner air by trapping 99.95 percent of pollutants, including formaldehyde.

And shoppers have their choice of a device that can humidify, purify and cool a room or purify, heat and cool a room. This being the 21st century, many of these can be connected to your home Wi-Fi, and they can be compatible with your voice assistant.

None of this technology comes cheap, with prices starting about $400 for a fan with an air purifier. The more features the fan has, the higher the price, with some models costing around $1,000.

There's no question that the Dyson Air Multiplier is a striking invention. Its sleek design and innovative technology set the blogosphere abuzz when it launched. Perhaps in the future, none of our fans will have visible blades.

Originally Published: Oct 26, 2009

Contents

News