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An air multiplier, sometimes called bladeless fan, is a fan which blows air from a ring with no external blades. Its vanes are hidden in its pedestal and direct the collected airflow through a toroid, blowing a thin high-velocity smooth airflow from a continuous slot across the surface of the tube or toroid.
The first concept was created by Toshiba in 1981. Industrial designer James Dyson used the technique in a consumer fan, terming it the air multiplier. Mitsubishi also uses a similar set up too. 
There are some drones which make use of bladeless fans instead of the old setup. 
The design places fan blades inside the base. The air is drawn in by a compressor and directed up into a ring. It comes out of a slit around the ring and passes over a shape like that of an aircraft wing (Coandă effect). This design generates airflow up to 55 miles per hour (25 m/s).
The fan's pedestal contains a brushless electric motor that rotates nine asymmetrically aligned mixed-flow blades attached to a rotor. Usually, the upper frame of this fan is ring-shaped. The frame's cross-section curves at a 16-degree angle slope.
Air flows through the channel in the pedestal and upwards into the ring. Then the air is shot out through a 16-mm slit at the edge of the ring. This air flows smoothly, rather than turbulently as with a conventional fan. The curvature of the inner wall creates an area of negative pressure like an airplane wing to draw more air into the flow, hence "multiplying" it. This action is called entrainment. The ambient air surrounding the ring flows with the direction of the air exiting the slit (is "entrained" to it). Dyson claims that the fan's air output is at least 15 times greater than the air volume entering the pedestal.
The Spanish consumer advocate Organización de Consumidores y Usuarios tested Dyson's first Air Multiplier (AM01) and remarked on the further-reaching and steadier stream. It was found to use 40W and move 2,700 m3/h (95,000 cu ft/h) at its maximum setting. However, it was noisier and much more expensive (€300–€400 versus €20) than bladed fans. Another test found the AM01's power consumption to be variable between 2-3W and 31W.
Geek.com performed airflow, noise level, and power measurements on the AM06 and, aside from the first setting, was found to achieve similar levels of air speed and air volume moved per second while being quieter (2–10dB) and more energy efficient per volume of air moved (6–3×) depending on the setting. The highest setting reportedly produced 1,150 cu ft/min (1,950 m3/h) and 548 ft/min (2.78 m/s). The volume was on par with an $80 regular fan and about twice as much as a $15 fan, while the air speed was roughly on par with both. At this setting, the AM06 produced 10dB less noise than either regular fan and used 20W, versus 60W and 40W used by the regular models. It concludes that while "there is more to the air multiplier than a bit of fancy plastic", "this data probably won't convince anyone to buy a Dyson AM06". "The Dyson is for doctor’s offices, executive suites, and other places where air flow is nice to have, but design is paramount."
- "Dyson fan: was it invented 30 years ago?". Telegraph. Retrieved 2014-01-09.
- "Sir James Dyson explains his bladeless fan". YouTube. Retrieved 2014-01-09.
- "JT-S2AP-W-NE Mitsubishi Electric Smart Hand Dryer | Intelligent Hand Dryers Australia".
- "The Dyson of Drones - Yanko Design". 18 August 2017.
- "How Does the Dyson Air Multiplier Work?". Jameco. Retrieved 2017-01-27.
- "How the Dyson Bladeless Fan Works". HowStuffWorks. 26 October 2009. Retrieved 2017-01-27.
- "Air Multiplier, un ventilador sin aspas". www.ocu.org (in European Spanish). Organización de Consumidores y Usuarios. 16 July 2012. Retrieved 23 May 2020.
- Jeremy Cole (12 April 2013). "Power consumption of Dyson Air Multiplier (AM01)".
- Sal Cangeloso (10 April 2014). "Best desk fan: Dyson vs Vornado vs Honeywell". Archived from the original on 2020-04-26.