Henri COANDA
Coanda Effect
Henri
Coanda
https://1lib.sk/book/5809396/788564/coanda-effect.html
Coanda Effect
Noor A Ahmed
US2052869
-- Device for Deflecting
a Stream of Elastic Fluid Projected into an Elastic
Fluid
Henri Coanda (Sept. 1, 1936)
It is an observed fact that when a stream or sheet of fluid issues through a suitable orifice, into another fluid, it will carry along with it a portion of the surrounding fluid, if its velocity is sufficient. In particular, if a sheet of gas at high velocity issues into an atmosphere of another gas of any kind, this will produce, at the point of discharge of the said sheet of gas, a suction effect, thus drawing forward the adjacent gas.
If, at the outlet of the fluid stream or sheet, there is set up an unbalancing effect on the flow of the surrounding fluid induced by said stream, the latter will move towards the side on which the flow of the surrounding fluid has been made more difficult.
It is thus evident that it will be possible, by a suitable checking of the surrounding fluid in one side of the orifice from which the fluid stream or sheet is discharged at high velocity, to act indirectly upon the direction of the issuing stream or sheet. In consequence, by the successive checking of the several layers of the fluid sheets on the proper side, if it is considered that the latter may be theoretically divided into layers to facilitate the demonstration, they may be made to follow any desired path.
Such is the object attained by the present invention, whose essential characteristic consists in the production of a determined unbalancing effect in the flow of the surrounding fluid induced by a sheet or stream of fluid which is discharged thereinto at high velocity.
For this purpose, the discharge orifices for the fluid each include, on the side toward which said sheet or stream is to be deflected, guiding means, for instance a flap which is suitably inclined according to the rate of flow and the velocity of the fluid, and said flap may be more or less extended and may be more or less inclined, according to the path which said stream is to be made to follow. On the other hand, by a proper knowledge of the physical constants of the surrounding fluid and of the fluid discharged into the same, it is possible to determine the optimum curve to be given to the means for guiding the stream, according to its rate of flow and velocity.
The invention further relates to the application of the said process for the deflection of fluid streams which penetrate with a high velocity into another fluid. In particular, it relates to its application to the change of direction of the direct reactions due to the abrupt discharges of one fluid into another, which reactions are even greatly increases by the fact that on the side which is not checked, the effect of suction is very greatly increased.
The accompanying diagrammatic drawing shows the direction of the streams of fluid which are discharged at high speed into another fluid through a nozzle, in the case of an equilibrium or lack of equilibrium of the facilities of withdrawal of the surrounding fluid at the sides of the stream.
Figure 1 shows the free discharge of a fluid stream 1, issuing from a nozzle, for instance, whose cross section has the form of a slot 2, also showing the induced flow of the surrounding fluid according to the arrows 3.
Figure 3 shows the checking of the surrounding fluid on one side of the stream by means of a flap 4 which prevents the flow of the surrounding air from space 5, and also the deflection, according to the arrows 3,of the issuing stream discharged from said nozzle.
Figure 3 represents the flap 4 which is extended according to a given outline, thus producing a strong suction, at 6, of a stream which is entirely turned about, according to the arrows 7. This will eliminate the impact upon the surrounding fluid, which occurs in front of a sheet of fluid discharged at high velocity into another fluid.
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Scientific
American (1980
"Applications of the Coanda Effect"
Imants Rebs
