|Publication number||US3283767 A|
|Publication date||Nov 8, 1966|
|Filing date||May 31, 1963|
|Priority date||May 31, 1963|
|Publication number||US 3283767 A, US 3283767A, US-A-3283767, US3283767 A, US3283767A|
|Inventors||Wright Christopher P|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (2), Referenced by (12), Classifications (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Nov. 8, 1966 c. P. WRIGHT JET FLUID AMPLIFIER Filed May 31, 1963 FIG. 1
FIG. 4 FIG. 5 FIGS THREADS FIG. 10
//V|/E/V7 0/? CHRISTQPHER F2 WRIGHT MACHINING FIG FIG. 9
ATTORNEY United States Patent 3,283,767 JET FLUID AMPLIFIER Christopher P. Wright, Endweil, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed May 31, 1963, Ser. No. 284,717 4 Claims. (Cl. 13781.5)
The present invention relates generally to fluid logic and it has reference in particular to pure fluid jet amplifiers.
Fluid switches, amplifiers and the like have been developed 'wherein all mechanical elements are eliminated and a fluid stream to be call-ed the power stream is switched to one or the other of two or more outlets by directing the flow of one or more low energy streams of the same fluid known as control streams transversely against the power stream. This method of control permits small, low-pressure control streams to direct the path of a high energy power stream. By utilizing a setback in the power stream channel wall in the region of the control streams, the deflected power stream is caused to more positively lock on to the wall of the channel to which it is deflected and remain there even though the deflecting control stream is discontinued. However, this type of operation is closely dependent on the pressure of the source of the power stream, and below Reynolds numbers in a predetermined range, positive lock-on of the switched stream after the controlled stream is discontinued cannot be always relied upon, because the stream will attach only if turbulent and the critical point of turbulence can vary over a wide range of Reynolds numbers dependent upon pressure surges.
Generally stated, it is an object of the present invention to provide an improved and more reliable jet fluid amplifier.
More specifically, it is the object of the present invention to provide in a pure fluid amplifier for facilitating transition of the flow in outer layers of the jet stream from laminar t-o turbulent further upstream or sooner, so as to permit reliable proper switching action at lower values of supply pressures that may be lower than usual to reduce the power requirements of the device.
It is an important object of this invention to provide for using means such as surface irregularities in the nozzle of a power stream for generating a turbulent boundary layer in the power jet stream prior to acting on it with a control jet, so that the control jet is more elfective and turbulent reattachment of the power stream may be effected at a lower than usual value of Reynolds number.
Another object of this invention is to provide for introducing a sharp protrusion at the edge of a power stream immediately prior to acting on it by a control stream, so as to facilitate turbulent reattachment of the main stream under lower supply pressure conditions than are otherwise possible.
Yet another object of the invention is to provide for roughening the walls of a supply passage or nozzle in a jet fluid amplifier ahead of a control port so as to facilitate switching the power stream by producing turbulent flow of the power stream sooner or further upstream than otherwise possible.
It is also an object of the invention to provide in a fluid amplifier for using corrugation-s in the supply or inlet nozzle of a main stream ahead of a control nozzle to induce turbulence and make switching of the main stream by a control stream less critical.
Another important object of the invention is to provide for'using rand-om surface irregularities in an inlet port of a main or power jet just ahead of a control port in a fluid amplifier for generating a turbulent boundary layer in the main jet and facilitating proper switching of a main jet at much lower supply pressures than usual.
It is furthermore an imporant object of this invention to provide for using mechanical means for producing turbulent reattachment of a power stream in a fluid device with the use of less setback and at a lower Reynolds number than heretofore considered possible.
Yet another object of the present invention is to provide for improving and making more reliable the operation of fluid amplifiers at low supply pressures.
The foregoing and other objects, features and advantages of the invention will be apparent from the following and more particular description of the preferred embodiments of the invention as illustrated in the accompanying drawings.
In the drawings:
FIG. 1 is a plan view of a pure fluid amplifier of the general type previously proposed;
FIG. 2 is an enlarged partial plan view of the amplifier of FIG. 1 showing the transition of a laminar jet stream to turbulent flow under low pressure conditions;
FIG. 3 is an enlarged partial plan view of a control amplifier modified in accordance with the invention to show the turbulence eifect of corrugations in the throat on the power stream flow under low pressure conditions;
The following FIGURES 4-10 illustrate diflerent modifications of the invention as disclosed in FIG. 3;
FIG. 4 is a partial isometric view of a portion of the throat wall incorporating the use of a trip wire on the wall for producing turbulence;
FIG. 5 is a diagrammatic representation of a portion of the wall in the throat of the main nozzle illustrating the use of spikes of sharp protrusions to produce eddies in the boundary layer, which propagate turbulence;
FIG. 6 is a diagrammatic representation of a throat nozzle illustrating the use of a suddent constriction to produce eddies;
FIG. 7 is a diagrammatic showing of a portion of the throat surface illustrating the use of particles of sand or the like to produce eddies;
FIG. 8 is a diagrammatic representation of a portion of a throat showing the use of machined. marks on the surface of the throat;
FIG. 9 is a diagrammatic representation of a portion of a throat showing the use of the abrasions or scratches in the throat for producing eddies; and,
FIG. 10 is a diagrammatic representation of a portion of the throat showing the utilization of threads for producing eddies.
Referring particularly to FIG. 1, the numeral 10 designates a body or plate of plastic or the like of which a bistable fluid amplifier is formed by machining or by an etching process in a manner well known in the art. As shown, a supply port 12 connected to a source of fluid' pressure has an inlet passage, throat or nozzle 14 which opens into a receiving chamber or areception region 16 defined by divergent side walls 17 and 18 on either side of a main or power stream 13 of jet fluid emitted from the nozzle 14; Control ports 20- and 2 2 are disposed on opposite sides of the throat 14, and are connected to the reception region 16 by means. of control nozzles 24 and 26 which are substantially transverse of the passage of the main power stream. 13 emitted from the throat 14;. Substantially, in line with the divergent. walls 17 and 18,.
As is well known in the art, the inlet port 12 may be" connected to a source of fluid under pressure for emitting.
a stream 13 of fluid such as air through the nozzle 14 into the reception region 16. The walls 17 and 18 are set back adjacent the exit of the nozzle 14 so as to provide for producing a turbulent boundary layer condition as the stream leaves the throat 14. Boundary turbulence causes a lower pressure area and a separation bubble 19 to a form adjacent one wall or the other and results in the locking on or turbulent reattachment of the power stream 13 to the wall 18, for example, so that the associated outlet port 34 receives a relatively large flow of fluid. Switching of the stream to the other outlet port 32 is produced by a control jet from the control port on the side to which the power stream is attached, which inflates the separation bubble 19, enlarges it and drives it downstream, releasing the power stream from the one wall and causing a pressure differential which creates a lower pres sure area adjacent wall 17 and permits turbulent reattachment to cause the power stream to lock on the other Wall 17 so as to supply a major portion of the fluid to the other outlet port 32.
As shown in FIG. 2, when the walls of the nozzle 14 are smooth, the stream 13 therefrom has substantially smooth or laminar flow for an appreciable distance from the nozzle 14. Typical dimensions of the nozzle may be, for example, .030 inch wide and .040 inch deep. With normal supply pressures on the order of /2 pound per square inch, boundary layer turbulence of the main stream occurs soon enough for the main stream to lock onto the adjacent wall 18. Switching to the other wall 17 is effected by a control stream from passage 26. Turbulence normally occurs at a predetermined value of Reynolds number in the region of 3000 when supply pressures are on the order of /2 pound per square inch of greater, and air is supplied at a rate of approximately 3500 cubic centimeters per minute. However, when the supply pressures are lower than normal, the transition point of laminar to turbulent flow occurs too far downstream of the main jet for turbulent reattachment to the walls to be effective, so that reliable switching of the main stream is not attained.
Referring to FIG. 3, it will be seen that the throat of the nozzle 14 is provided with a mechanical means such as a plurality of corrugations adjacent its entrance into the reception region 16. These corrugations 15 tend to induce boundary turbulence in the outer layer of the otherwise laminar flow stream from the nozzle, so that the necessary transition from laminar to turbulent flow in the outer layers of the power stream occurs sooner or further upstream, and turbulent reattachment of the power stream to the wall 18 occurs soon enough for the attachment to be effective and lock the stream to wall 18, even at supply pressures that would otherwise be too low to effect turbulent reattachment.
The power stream 13 is switched by a control jet from control nozzle 26 which inflates the separation bubble 19, increases the pressure therein, and moves it downstream until the power stream 13 separates from the wall 18 and transfers to wall 17 because of the change in pressures on opposite sides of the stream. It has been found that by utilizing corrugations and the like that turbulent reattachment may be effected for 21 Reynolds number on the order of 2000 or less, for supply pressures as low as one quarter of a pound per square inch.
Rferring to FIG. 4, the reference numeral 40 designates other mechanical means such as a trip wire or the like secured to the surface wall of the throat 14 by soldering, welding or brazing for producing eddies as is indicated by the curved arrows on the downstream side side of the wire, which initiate the formation of a turbulent boundary layer in the power stream, thus expediting control of the power stream by a control stream at lower values of Reynolds numbers.
Referring to FIG. 5, the numeral 42 designates a sharp protrusion such as a spike located, for example, in one or both of the side Walls of the nozzle 14, which is likewise effective to produce eddies as indicated by the curved arrow on the downstream or outlet side of the protrusion, thus expediting the formation of a turbulent boundary layer and effective control of the power stream at lower than normal values of supply pressure.
Referring to FIG. 6, it will be seen that a sudden reduction in the size of the nozzle 14 to a smaller passage 14a produces a sharp entrance constriction 44 which is likewise effective to produce eddies in the boundary layers of the power stream and expedite the formation of a turbulent boundary condition which facilitates turbulent reattachment of the stream at lower values of supply pressure under the control of a control stream.
Referring to FIG. 7, the reference numeral 46 designates a random roughness produced by a number of grains of sand or the like secured to the side walls of the throat or nozzle 14 by means of a suitable cement or the like, for purpose of producing a turbulent condition in the boundary layers of the stream similar to those produced by the corrugations of FIG. 3.
FIG. 8 illustrates another method of mechanically producing turbulence by roughening the surface of the nozzle 14 to produce turbulent boundary conditions in the power stream, such as by machine marks or cuts 48 on the surfaces of the throat.
FIG. 9 illustrates still another method of providing surface irregularities or roughness in the throat or nozzle 14 by means of scratches 50 produced by abrasion of the surface walls. Still another method of using surface roughness is effective to provide turbulent boundary layer conditions in the power stream is the provision of threads 52 as shown in FIG. 10.
Fluid amplifiers embodying the present invention may be readily produced by using an optical etching process with a suitable photopolymer. The body may, for example, comprise a layer of photopolymer used with an aluminum backing plate in a manner known in the art. The photopolymer is subjected to ultraviolet light through a suitable mask defining the desired flow pattern. This hardens the exposed regions and the masked areas may be removed or washed away by a sodium hydroxide solution or the like. Roughening of the throat areas may be readily produced by placing the desired roughness characteristics on the mask so that they are transferred to the body.
From the above description and the accompanying drawings, it will be seen that providing either random or uniform roughness or other mechanical means in the throat or nozzle of the power stream of a fluid amplifier facilitates the transition of a laminar to a turbulent flow in the boundary layers and enables turbulent reattachment of the power stream to take place at lower than usual supply pressures. In addition, by effecting more reliable switching of the power stream, better separation of the outlet ports is permitted. Spillover between the output ports is prevented and either the angle of divergence of the walls of the reception region may be varied and/or the distances between the power nozzle and the output ports may be varied without materally altering the efiiciency of the fluid amplifier. This means that manufacturing tolerances need not be so close, so that production of amplifiers is greatly expedited.
While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that the changes in form and detail may be made therein without departing from the spirit and scope of the invention.
What is claimed is:
1. In fluid control apparatus:
(a) a main nozzle connected to a source of fluid under pressure for producing a fluid power stream,
(b) a divergent wall disposed on at least one side of the power stream,
(c) an outlet port disposed adjacent said wall for receiving a portion of said stream,
(d) a control jet disposed on the other side of the stream for directing a transverse control stream to control said power stream, and
(e) means including a plurality of random surface protrusions on an inner wall of the nozzle adjacent the end thereof for inducing turbulence in the outer portions of the stream to insure turbulent reattachment and provide for control of the main stream by the control stream at lower supply pressures.
2. Fluid control apparatus comprising:
(a) a main power nozzle connected to a source of fluid under pressure for providing a main fluid power stream,
(b) divergent wall means disposed along opposite sides of said stream,
(c) an outlet passage disposed along each of said Wall means,
(d) transverse control ports located on the opposite sides of the stream adjacent the nozzle for directing control streams to alter pressure conditions on opposite sides of the main stream and deflect the main stream in a plane through the control ports, and
(e) means in the nozzle providing an abrupt projection into the power stream to induce turbulent boundary flow in outer portions of the laminar power stream before it is impinged on by the control stream for achieving turbulent reattachment of the power stream to one of said divergent side walls, at values of Reynolds numbers on the order of 2000 or less for power stream source pressure below /2 lb. per square inch.
3. A fluid control device comprising:
(a) a main nozzle connected to a source of fluid under pressure for producing a main fluid power stream, (b) a pair of divergent walls one on either side of the main stream defining a reception region,
(c) a pair of fluid outlet ports located one along each of said walls,
((1) a pair of control nozzles disposed one on each side of the main stream adjacent the end of the main nozzle for selectively directing a control stream into the reception region toward the main stream, and
(e) means providing a sharp constriction in the main nozzle adjacent the reception region to induce turbulence in the boundary layers of the main stream prior to entering the control stream portion of the reception region to produce turbulent reattachment of the main stream to their respective walls at a lower Reynolds number whereby the control streams are I rendered effective to control the power stream.
4. In a fluid control device:
(a) a main power nozzle connected to a source of fluid under pressure for providing a main flow power stream,
(b) a pair of divergent side walls defining a reception region adjacent the end of the nozzle,
(c) a pair of outlet ports disposed one along each of said side walls,
(d) a pair of control ports one on each side of the power stream connected to a source of fluid under pressure to provide control streams transversely of said main stream for shifting turbulent reattachment of the power stream to the Wall on the other side of the power stream, and
(e) one or more Wires disposed along the Walls of the main nozzle normal to the power stream and ahead of the control streams for inducing turbulent boundary flow therein whereby the control streams are rendered effective to change turbulent reattachment of the main stream from one side wall to the other at lower values of pressure of the power source.
References Cited by the Examiner UNITED STATES PATENTS 5/1965 Horton 137--8l.5 5/1965 Zilberforb et a1 1378l.5
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|International Classification||F15C1/00, F15C1/08|