Coanda effect


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Coanda effect

or

wall-attachment effect,

the tendency of a moving fluid, either liquid or gas, to attach itself to a surface and flow along it. As a fluid moves across a surface a certain amount of friction (called "skin friction") occurs between the fluid and the surface, which tends to slow the moving fluid. This resistance to the flow of the fluid pulls the fluid towards the surface, causing it stick to the surface. Thus, a fluid emerging from a nozzle tends to follow a nearby curved surface—even to the point of bending around corners—if the curvature of the surface or the angle the surface makes with the stream is not too sharp. Discovered in 1930 by Henri Coanda, a Romanian aircraft engineer, the phenomenon has many practical applications in fluidicsfluidics,
branch of engineering and technology concerned with the development of equivalents of various electronic circuits using movements of fluid rather than movements of electric charge.
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 and aerodynamicsaerodynamics,
study of gases in motion. As the principal application of aerodynamics is the design of aircraft, air is the gas with which the science is most concerned. Although aerodynamics is primarily concerned with flight, its principles are also used in designing automobile
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.

Coanda effect

[kō′an·də i′fekt]
(fluid mechanics)
The tendency of a gas or liquid coming out of a jet to travel close to the wall contour even if the wall's direction of curvature is away from the jet's axis; a factor in the operation of a fluidic element.

Coanda effect

Coanda effect
The effect of a jet of air blowing out from an airfoil, or another shape, and reacting with air passing. The air tends to stick to the solid surface even if it curves away, avoiding separation or stall.
References in periodicals archive ?
Coanda effect was realized which prevents direct throw of cold and hot air to the occupied zone.
This pressure creates a high-velocity jet of air dispersed out of six slots around the barrel, generating the Coanda effect, which allows hair to curl automatically around the barrel to style.
One of the most important factors in improving efficiency of tunnel ventilation systems is minimizing the Coanda effect. "Coanda effect" refers to the tendency of the air steam produced by each jet fan to be drawn to nearby walls, leading to increased friction and significantly increasing the energy required to move the air.
In the region above the backflow, the smoke adheres to the left wall surface, namely the boundary layer attachment or the Coanda effect (Zhuang et al.
The abstract of a paper published in Environmental Science and Technology reads in part, "Lidar and point sampler measurements show that, as long as the intervention takes place within the zone where the Coanda effect holds the jet to the surface lie., within about 70 m in this case], then quite modest surface-mounted baffles can rapidly lift the jet away from the ground."
Thus, the inlets have been located at the ceiling and a Coanda effect was expected.
Williams is engineering a new noise-attenuating inlet for the nacelle, along with a passive thrust-vectoring system that will use the Coanda effect to deflect thrust 23 deg.
It is designed to release a high level of plasmacluster ions at 20 degrees upward angle that is varied along every part of the interior of the car by the Coanda effect. It functions at a low power consumption of 1.3W and is known for its long service life where the ion generating device needs to be changed every 19,000 operating hours.
The supply of inlet jets creates plane jets to both sides of the beam that normally attach to the ceiling, utilizing the Coanda effect. Figure 2 shows the operation principle of an active chilled beam.
The YC-15 introduced a number of innovative features, such as externally blown flaps, which used double-slotted flaps to direct part of the jet exhaust downwards, while the rest of the exhaust passed through and downward over the flaps, introducing the Coanda effect. It was also the first military aircraft with a supercritical airfoil.
The new product features an air compression chamber that makes use of the Coanda effect principle to collect air as it leaves the blowers and compress it into a concentrated stream, which covers the entire door opening.