US3362421A - Bounded free jet fluid amplifier with turbulent attachment - Google Patents

Description

Jan. 9, 1968 R. R. SCHAFFER BOUNDED FREE JET FLUID AMPLIFIER WITH TURBULENT ATTACHMENT Filed May 28 1963 I 3 Sheets-Sheet l v FIG. 1

FIG.4

' JA/I ENTOR I ROBERT R. SCH FER BY 347 g ATTORNEY Jan. 9, 1968 R. R. SCHAFFER 3,362,421

BOUNDED FREE JET FLUID AMPLIFIER WITH TURBULENT ATTACHMENT Filed May 28, 1963 3 Sheets-Sheet 2 i L TURBULENT LAMINAR CORE v TURBULENT--\- Jan. 9, 1968 R. R. SCHAFFER 3,362,

BOUNDED FREE JET FLUID AMPLIFIER WITH TURBULENT ATTACHMENT Filed May 28, 1963 5 Sheets-Sheet 5 PRIOR ART ARRANGEMENTS DOFL AMPLIFIER United States Patent O 3,362,421 BOUNDED FREE JET FLUID AMPLIFIER WITH TURBULENT ATTACHMENT Robert R. Schaifer, Endicott, N.Y., assignor to International Business Machines Corporation, New York,

N.Y., a corporation of New York Filed May 28, 1963, Ser. No. 283,875 9 Claims. (Cl. 137-81.5)

This invention relates to fluid jet amplifiers, and more particularly to one wherein a laminar free jet stream normally discharges into a substantially coaxially aligned outlet but, when rendered turbulent by a control pressure signal, is caused to attach to a side wall and be discharged from an outlet associated with such wall.

There has been considerable interest in recent years in fluid amplifiers of various types. In the January 1963 issue of Control Engineering magazine, at pages 88 through 93, there is a comprehensive discussion of the so-called DOFL (Diamond Ordnance Fuze Laboratories) amplifier and also of a so-called turbulence amplifier.

In the DOFL amplifier, a turbulent fluid jet issues from an inlet and is deflected by a control jet of lesser energy toward a nearby wall. As the jet is deflected toward the wall, ambient fluid is entrained, causing a reduced pressure between the jet and the wall. This, in turn, causes the jet to move toward and then to lock on to said wall and create a separation bubble in the boundary control region adjacent the exit end of the inlet. The stream will remain thus locked to said wall even after the control pulse dies. The stream is switched away from such wall by inflating the separation bubble until the stream is literally forced away from such wall.

On the other hand, in the turbulence amplifier, fluid at a very low constant supply pressure flows from a supply tube across an air gap into a coaxially aligned receiving tube so long as the stream is laminan'However, a relatively small fluid or acoustical control pressure signal will cause the laminar stream to explode into a turbulent cone and thus substantially reduce the output pressure obtained in the receiving tube. The turbulence amplifier is essentially a threedimensional device with but a single outlet (i.e., the receiving tube) wherein a high outlet pressure denotes the absence of a control signal and a low pressure denotes the presence of such signal.

Thus, one disadvantage of the turbulence amplifier is that itis basically a NOR device with but a single outlet; and another disadvantage is its relatively slow response time. On the other hand, one of the serious disadvantages of the DOFL type amplifiers is their need for a highvolume high-pressure fluid source; and another disadvantage is that inflation of the separation bubble to switch the stream requires not only fluid pressure but also a certain volume of fluid, thus retarding response time.

It is therefore one object of this invention to provide an improved two-dimensional pure fluid amplifier wherein a power stream can be converted from a laminar state into turbulent attachment along a Wall thereby to provide discrete outputs in more than one distinct outlet.

Another object is to provide an improved fluid amplifier providing discrete outputs for both logical NOR and logical OR conditions.

A further object is to provide an improved two-dimensional fluid amplifier wherein a normally laminar stream is rendered turbulent by an appropriate fluid or acoustical control pressure signal to cause diversion of the stream into a corresponding selected outlet.

Another object is to provide an improved pure fluid amplifier of the turbulent attachment type which is capable of operating reliably at lower supply pressures than heretofore possible.

3,362,421 Patented Jan. 9, 1968 Still another object is to provide an improved twodimensional multiple discrete output fluid jet amplifier which is sensitive to acoustical signals.

And still another object is to provide a two-dimensional fluid jet amplifier which operates at a low supply pressure and in which a fluid stream is switched responsively to a low pressure signal with negligible fluid flow.

According to these objects, there is provided an improved two-dimensional pure fluid jet amplifier wherein a laminar fluid stream normally flows from an inlet into a substantially coaxially aligned outlet. At the exit end of the inlet are two spaced side walls that lead to respective other outlets disposed at opposite sides of the aligned outlet. When a control pressure signal (fluid or acoustical) is supplied to a control port adjacent the exit end of the inlet and opening through a respective one of said walls, the fluid stream will be rendered turbulent and cause turbulent attachment of the stream to that wall opposite the control port to which the signal was supplied. The stream will remain attached to that particular side wall and produce an output in the associated outlet only as long as the control signal lasts. After the signal dies, the jet stream will resume its laminar state and once again discharge into the c-oaxially arranged outlet.

Means are provided to damp out and substantially eliminate fluctuations in the pressure of the fluid stream as its exits from the inlet. This intentionally raises the value of critical Reynolds number at which flow of stream fluid will change from laminar to turbulent, the Reynolds number being a measure of the ratio of fluid inertia forces to viscous forces. Raising the critical value of Reynolds number for a particular amplifier configuration permits the use of higher fluid pressures and stream velocities before turbulence will occur. The higher stream velocities, in turn, provide more rapid response times. (By way of contrast, in the DOFL amplifiers, efforts are directed toward reducing rather than raising the critical Reynolds number to assure the turbulence necessary for turbulent attachment with the smallest pressures and flow rates possible. However, the lowest Reynolds number permissible with DOFL amplifiers is considerably higher than the highest Reynolds number usable with the amplifiers embodying the invention.)

Moreover, unlike the DOFL amplifier and turbulence amplifier, only the outer layers of the stream are rendered turbulent by the pressure signal. The inner core remains laminar and hence in tact to provide a definite wall attachment and a higher percentage recovery of the supply fluid than is obtained with either the DOFL or turbulence amplifier.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the fluid amplifiers em bodying the invention, as illustrated in the accompanying drawings, wherein:

FIG. 1 is a front elevational view, partly broken away, of a fluid amplifier constructed according to one embodiment of the invention, for response to fluid pressure signals;

FIG. 2 is a section taken along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged view of a portion of FIG. 1, showing details of the flow-steadying vanes shown to smaller scale in FIG. 1;

FIG. 4 is a front elevational view, partly broken away, of a fluid amplifier constructed according to another embodiment of the invention and responsive to acoustical a well as fluid pressure signals;

FIG. 5 is an end view taken from the right-hand end of FIG. 4;

FIG. 6 is an enlarged view of the left-hand boundary layer control region of the amplifier shown in FIG. 4;

FIG. 7 is a schematic diagram showing the logic functions performed by the amplifier shown in FIGS. 4 and 5; and

FIGS. 8 and 9 are front elevational views of a turbulence amplifier and a DOFL amplifier, respectively, of types heretofore proposed and showing how their respective fluid streams respond to control signals, thereby more clearly to show the differences between such prior art amplifiers and those embodying the present invention.

Description The fluid amplifier devices embodying the invention are illustrated as comprising a photo-etched plate 19 secured by a photo-resistive bonding layer ill to a metal backing plate 12 to which all external fluid connections are made. The front face of the etched plate is sealed by an overlying piece of transparent, adhesively attached tape 13.

Referring to FIGS. 1 to 3, a stream of pressure fluid that may be in a turbulent state is supplied from a suitable source (not shown) via a supply pipe 14 to a wide elongated chamber 15 containing a plurality of parallel arranged flow-steadying ribs 16. These ribs co-operate with a long narrow straight stabilizing channel or inlet 17 to assure that a fluid stream will be discharged in a laminar state from the inlet into a chamber 18. This chamber is defined between side walls 19 and 20 that, as illustrated, diverge with very slight, almost negligible set back and at equal acute angles from the exit end of the inlet. Control ports 21 and 22 open through the side Walls 19 and 2t respectively, adjacent the exit end of the inlet 17. These ports 21 and 22 are respectively connected to control conduits 23 and 24 to which low energy pressure fluid signals are adapted to be supplied selectively from suitable sources (not shown) by selectively operable valves V to control switching of the fluid stream. As illustrated, each valve V is operable to selectively connect respective conduit 23 or 24 to atmosphere or to the pressure signal source.

If the fluid stream flows along wall 19, for example, it will discharge primarily via a duct 25 into an outlet pipe 26 connected to plate 12. Similarly, if the fluid stream flows along Wall Ztl, it will be discharged primarily via a duct 27 into an outlet pipe 28 connected to plate 12. However, the fluid stream will normally discharge into a duct 29 that is connected to an outlet pipe 30 and is arranged substantially coaxially with the inlet 17 and substantially midway between the ducts 25 and 27.

Operation Assume initially that fluid i supplied to the supply pipe 14 and is discharged from inlet 17 at a substantially constant pressure and in a laminar state by the combined action of the flow-steadying ribs 16 and stabilizing inlet. Assume further that fluid at the same pressure (such as atmospheric) is being supplied to both control conduits 23, 24.

Under these conditions, the laminar stream issuing from inlet 17 will remain laminar and discharge into the substantially coaxially arranged duct 29, as indicated by the flow lines in FIG. 1.

If pressure fluid is now supplied to control conduit 24 to provide a low energy pressure pulse signal therein, this signal will render the outer shear layer of the fluid stream turbulent but permit the inner core of the stream to remain substantially laminar. The interaction of this side-injected pressure signal with the stream will create a pressure imbalance across the stream, with lower pressure being on the side of the stream opposite the control signal. As a result of this imbalance, the stream will start to move toward the wall 19. This, in turn, will cause some fluid to be entrained between wall 19 and the stream, and develop a low pressure in the boundary layer control region 19 adjacent said wall. Thereafter, as the turbulent shear layer of the stream interacts with wall 19, the

lstream will move progressively leftward until the stream attaches to said wall due to the turbulent attachment feature characteristic of the DOFL fluid amplifiers. However, unlike the DOFL amplifiers, the stream will not remain locked on to wall 19 after the control pulse signal dies.

As soon as the control pressure signal that had agitated the fluid stream into turbulence dies or is terminated, the fluid stream particles leaving the inlet 17 will remain laminar and once again discharge into central duct 29. Thus the stream will effectively leave the side wall 19 because lock-on to such wall can occur only if and so long as the stream remains in a turbulent state.

In similar manner, by supplying a pressure pulse signal to control conduit 23, the stream can be switched to the right hand duct 27. But the stream will stay switched into duct 27 only as long as the signal lasts.

It will thus be seen that the fluid amplifier embodying the invention is a two-dimensional device capable of providing discrete outputs in any one of three distinct outlets 26, 28 or 30. While no pressure signal is supplied to either control conduit 23 or 24, the fluid stream will remain laminar and discharge into outlet pipe 30 to denote this NOR condition. On the other hand, so long as a signal is being supplied to either control conduit 23 or 24, agitation and turbulent attachment of the fluid stream to the opposite side wall will occur. Thus, an output in outlet 26 or 28 will denote that an OR condition exists; i.e., that control conduit 24 or 23, respectively, is pulsed.

It has been found, in the models tested, that when a fluid pressure signal is simultaneously supplied to both control conduits 23 and 24, the opposing unbalancing effects cancel out; and hence the stream will continue to discharge into the central duct 29. If a fluid pressure signal is supplied to one control conduit, such as 24, and then after turbulent attachment to wall 19 a signal is concurrently also supplied to the other control conduit 23, it has been found by actual test that turbulent attachment of the stream will cease, and it will discharge into central duct 29.

It is to be noted that auxiliary escape ports 31 and 32 are provided at the downstream ends of the side walls 19 and 20, respectively. These escape ports 31 and 32 bleed off any excess pressure fluid when the fluid stream is diverted into the respective outlets 26 and 28 and prevent impedances in said outlets from causing separation of the jet from the side wall.

The device shown in FIGS. 4 to 6 differs from that shown and described in connection with FIGS. 1 to 3 in that an acoustical (rather than fluid) pressure signal is used to agitate the fluid stream into turbulence. More specifically, the device of FIGS. 4 to 6 includes a Helmholz resonator comprising cavity 40 with a resonant frequency determined by the relationship of the volume of the fluid in the cavity to the volume of fluid in the throat 41. An acoustical signal is adapted to be delivered to the resonator cavity 40 by suitable means,'such as an ear phone 42 (FIG. 5). Upon receipt of the acoustical signal, the resonator will produce a pressure wave that will act in much the same manner as a fluid pressure signal to render the outer layer of the fluid stream turbulent and cause it to shift to and attach to side wall 19, in the manner already described.

The resonator amplifies the tone of the signal supplied by the ear phone and helps to attenuate extraneous frequencies. Note that the acoustical pressure signal must be focused to strike the fluid stream after it emerges from inlet 17; otherwise, the stream will not be agitated into turbulence. For example, even if a large electrostatic speaker emits acoustical pressure waves of the proper f equency in the general vicinity of the amplifier device, if these waves are not focused to strike the fluid stream, the stream will not be rendered turbulent.

It has been found that the frequency range with greatest acoustic power and hence the most sensitivity is in the band from about 1.5 to 3.0 kilocycles. Resonance appears to occur in this band despite considerable variations in amplifier geometry.

The configuration illustrated in FIGS. 4 to 6 actually permits switching of the fluid stream to duct 25 either by supplying a fluid pressure signal to conduit 24 or supplying an acoustical pressure signal to the resonator cavity 40, as shown schematically in FIG. 7. It is to be noted that the fluid pressure signals propagate at the subsonic velocity corresponding to the fluid velocity, whereas acoustical pressure signals propagate at the speed of sound. Where acoustical signals are supplied, faster overall switching times will be achieved with a device comprising a plurality of fluid amplifiers because of the faster propagation of an acoustical signal from amplifier to amplifier.

It also should be noted that in both of the embodiments above described, the actual critical value of Reynolds number at which turbulence occurs will vary over a broad range that is dependent upon the particular geometry of the amplifier (i.e., widths, lengths and smoothness of ports, etc.) and also on flow steadiness. The flow-steadying ribs 16 and long narrow inlet 17 are provided to damp out pressure fluctuations to achieve a more nearly constant pressure for the fluid discharging from the inlet. This reduces the possibility of turbulence, and assures that turbulence will occur at a correspondingly higher value of Reynolds number that permits an increased stream velocity and hence more rapid response time.

A full appreciation of the advantages of the devices embodying the invention can best be understood by comparing them with the turbulence amplifier and DOFL amplifier forming part of the prior art.

In the turbulence amplifier, as shown in FIG. 8, a low energy fluid pressure signal 50 injected from signal pipe 51 interacts with a normally laminar fluid stream 52 that discharges from a long supply tube 53 and, after crossing a predetermined gap, normally enters a coaxially aligned receiving tube54. However, as a result of this interaction and after a certain time delay, the jet stream 52 literally explodes into a three-dimensional cone 55 having an apex at 56 at the upstream end of the cone. As a result of such explosion, the output signal in receiving tube 54 is eifectively lost.

Now, as the fluid pressure in the supply tube 53 and thus the critical value of the Reynolds number is raised, the apex 56 of the cone 55 will move leftward toward tube 53 until finally the jet stream is turbulent as soon as it leaves tube 53. On the other hand, acoustic sensitivity increases as the gap between the tubes 53, 54 increases up to an optimum value beyond which the jet stream begins to wander. Thus, with the turbulence amplifier, the fluid stream is normally laminar; but after a relatively long time following a fluid pressure or acoustical pressure signal, the stream is rendered turbulent by an explosive action that dissipates or scatters the stream fluid and renders it ineflectual.

0n the other hand, with the DOFL amplifier, as shown in FIG. 9, response times are relatively rapid but the device requires relatively high operating pressures and flow volumes, and hence its power requirements are undesirably high. To reduce the power requirements as much as possible, DOFL devices should be operated at a Reynolds number which is as low as possible and is preferably only a slight degree above the critical value. This provides, with the lowest possible pressures and flow, the turbulence necessary to assure the turbulence attachment and lock on characteristic of the DOFL devices.

In the amplifier devices embodying the invention, power consumption can be kept small because the jet stream is essentially laminar, and hence the device operates at 21 Reynolds number below the critical value. However, if better response times are desired, they can be obtained by using the ribs 16 and long inlet 17 to raise the critical value of Reynolds number at which the stream goes turbulent. This permits fluid to be used at a higher supply pressure which, nevertheless, is below the higher critical value of Reynolds number obtained by using ribs 16 and the long inlet 17. In this way, response times are obtainable approaching those of the DOFL amplifiers and considerably better than those of the turbulent amplifiers.

In any event, whether or not these ribs 16 are used, the devices embodying the invention have been found by actual test to operate reliably and rapidly at lower supply pressures and flow rates than are possible with DOFL type devices. This can best be appreciated from the following example:

Assume that a DOFL amplifier operating with a supply or inlet pressure of /2 p.s.i. (lb. per square inch) has an inlet nozzle width L (FIG. 9) of .030 inch; that this provides a Reynolds number of 3,000, that is above the critical value; and hence that the stream is turbulent as it discharges from the inward nozzle. Assume further that, in the amplifiers according to the present invention, the substantially constant pressure of fluid as it emerges from the inlet 17 is /3 p.s.i.; that the inlet 17 has a width of .030 inch equal to that of the DOFL nozzle width L; that this provides a Reynolds number of 2,000, which is below the critical value; and hence that despite this relatively high pressure, the ribs 16 and long inlet 17 assure a laminar discharge at a steady pressure from the inlet.

The Reynolds number for fluid in a turbulent state is proportional to the product of the square root of the supply pressure and the supply nozzle width L. But when fluid is in a laminar state, the Reynolds number is directly proportional to the product of the supply or inlet pressure and width of inlet 17.

Hence, if it is desired to reduce the supply nozzle width L and width of inlet 17 to .015 inch (i.e., half its former width) to reduce pressure requirements and improve response times in the DOFL and present devices, respectively, then, in the DOFL device, the Reynolds number can be kept constant at 3,000 only by multiplying the inlet pressure by four; but in the devices embodying the invention, the Reynolds number can be kept constant at 2,000 merely by multiplying the inlet pressure by two. Thus, in the assumed example, in the DOFL device, the inlet pressure would have to be increased from /2 p.s.i. to 2 p.s.i.; whereas in the device embodying the invention, it would have to be increased only from /3 p.s.i. to /3 p.s.i.

This clearly demonstrates that fast response times can be achieved with relatively low supply pressures in the devices embodying the invention.

Moreover, the control signals need not be of the high energy level required for the DOFL devices. In the DOFL devices, there must be a control pressure signal and fluid flow in C (FIG. 9) s'uflicient to inflate or enlarge the separation bubble B and thus effectively switch the locked on stream from outlet X to outlet Y. But since there is no appreciable flow of the control signal fluid in the devices embodying the invention, relatively low energy control signals can be used to effect switching.

Furthermore, the time required to inflate the separation bubble B of the DOFL amplifier to separate the stream from one wall and release it for attachment to the opposite wall, constitutes the major fraction of the total switching time; whereas in the devices embodying the invention, the total switching time is merely the time required for moving the stream from the central outlet 30 and eifecting turbulent attachment to a wall.

Moreover, itshould be noted that, in either of the embodiments above described, the side walls 19 and 20 preferably diverge directly from the exit end. of the inlet 17 without appreciable set back. Actually the set back S (FIG. 6) is about one-fourth the width of inlet '17, and in no event need it exceed one-half such width. However,

with the DOFL type amplifiers, set back must be considerably greater to assure reliable lock on operation.

It might here be noted that the side walls 19 and 2% need not diverge angularly from the exit end of the inlet 17. These walls conceivably could be substantially parallel but spaced far enough to either side of the inlet 17 to assure, for a given width of inlet, three discrete outputs into the three distinct outlets 26, 28, 30 without cornmingling. In any event, the walls (whether divergent or not) are provided to limit lateral travel of the jet stream and so locate the stream relative to the outlets 26, 28 as to assure maximum pressure recovery.

Finally, it will be understood that in FIGS. 1 to 3, single control conduits 23 and 24 were shown at each side of the chamber 18, for sake of simplified illustration. However, multiple control conduits (even more than 22, 41, shown in FIGS. 4 and 6) may be ORd together to produce a pressure signal sufficient to render the outlet layer of the fluid stream turbulent if any one or any certain number of the plurality control conduits were pulsed.

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 foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A fluid logic device comprising means defining an inlet for receiving a fluid power stream, a wall adjacent one side of the exit end of the inlet and extending downstream from the inlet, one outlet into which the stream discharges so long as it remains laminar, another outlet into which the stream discharges while it is in turbulent attachment with said wall,

means for steadying the pressure of the stream fluid and assuring that the stream, even if initially turbulent, will be laminar before its discharge from said inlet to permit use of high stream fluid supply pressures that would otherwise cause the critical value of Reynolds number to be exceeded and the stream rendered turbulent, and

means for supplying a low energy pressure signal to the side of the stream opposite said wall as the stream discharges from said inlet to agitate the outer layers of the stream into turbulence and create a pressure imbalance that will cause turbulent attachment of the stream to said wall while said signal lasts.

2. A fluid logic device comprising means defining an inlet for receiving a fluid power stream, a wall adjacent one side of the exit end of the inlet and extending downstream from the inlet, one outlet into which the stream discharges so long as it remains laminar, another outlet into which the stream discharges while it is in turbulent attachment with said wall,

means for steadying the pressure of the stream fluid and assuring that the stream, even if initially turbulent, will be laminar before it discharges from said inlet to permit use of high stream fluid supply pressures that would otherwise cause the critical value of Reynolds number to be exceeded and the stream rendered turbulent, and

means for focusing a low energy acoustical pressure signal within a preselected frequency range on the side of the stream opposite said wall and just downstream of the inlet to agitate the stream into turbulence and create a pressure imbalance across the stream that will cause its turbulent attachment to said wall only while said signal lasts,

whereby when the signal ceases, the stream will revert to its completely laminar state and resume discharge into said one outlet.

3. A fluid logic device according to claim 2, wherein said means for supplying the acoustical pressure signal includes a Helmholz resonator, and the frequency of such signal is within the band of approximately 1.5 to 3.0 kilocycles.

4. A fluid logic device comprising means defining an inlet for receiving a fluid power stream, two walls disposed downstream of and at opposite sides of the exit end of the inlet, two spaced outlets into which the stream is selectively directed when caused to flow along one or the other of said walls, and two control ports each opening through a respective one of the walls adjacent the exit ends of the inlet, characterized by the provision of:

means for damping out pulsations in the pressure of the stream fluid and rendering the stream laminar, even if initially turbulent, prior to its discharge from the exit end of the inlet to cause it normally to flow in a laminar state between and to discharge into neither of said outlets and permit stream fluid to be supplied at higher supply pressures than otherwise possible Without exceeding the critical value of Reynolds numher at which turbulence occurs, and

means for supplying pressure pulse signals selectively to said control ports to agitate the stream into turbulence and create a pressure imbalance across the stream that will cause its turbulent attachment to that wall opposite the control port to which the signal was supplied and thus discharge primarily into the outlet associated with the last-mentioned wall.

5. A fluid logic device comprising means defining an inlet for receiving a fluid power stream, two oppositely disposed walls that diverge from the vicinity of the exit end of the inlet, two outlets into which the stream is selectively directed when caused to flow along one or the other of said walls, and two control ports each opening through a respective one of the walls adjacent the exit end of the inlet, characterized by the provision of:

means upstream of the inlet for render-ing the stream laminar prior to its discharge from the exit end of the inlet so that the stream, even if initially turbulent, will be laminar as it leaves said inlet,

another outlet into which the stream discharges after leaving the inlet and so long as flow remains laminar, and

means for supplying low energy pressure pulse signals selectively to said control ports to render the outer layers of the stream turbulent and create a pressure imbalance across the stream that will cause it to attach to that wall opposite the control port to which the signal was supplied and thus discharge primarily into the outlet associated with the last-mentioned wall.

6. A fluid logic device comprising means defining an inlet for receiving a fluid power stream, two outlets arranged in divergent relation to the exit end of the inlet, a third outlet substantially aligned with the inlet and into which the stream discharges after leaving the inlet so long as its flow remains laminar, and control apertures adjacent the exit end of the inlet,

means for rendering the stream laminar and also damping out pressure fluctuations therein prior to its discharge from the exit end of the inlet, and

means for supplying pressure pulse signals selectively to said control apertures to render the outer shear layers of the stream turbulent and create a pressure imbalance across the stream so long as such signal lasts for causing the stream to discharge primarily through that one of the said two outlets remote from the pulsed control port only so long as said signal lasts, such that when the signal terminates, the stream will automatically resume its laminar state and discharge into said third outlet.

7. A two-dimensional fluid logic device comprising means defining a supply chamber for receiving a fluid stream in a turbulent state,

an elongated narrow inlet for converting the stream from turbulent to laminar flow by the time the stream discharges from the exit end of the inlet,

one outlet substantially coaxially aligned with the exit end of the inlet and into which thestream normally discharges, a plurality of other outlets disposed laterally adjacent said one outlet and into which the stream is selectively switchable when rendered turbulent,

Walls spaced laterally from the normal path of the stream each for directing the stream into a respective one of said other outlets While the stream flows along such Wall at least one control port adjacent the exit end of the inlet, and

means for conveying pressure signals to each such control port to act on the stream as it discharges from the inlet to render its outer layer turbulent and cause it to flow along a selected one of the Walls and discharge from a corresponding one of said other outlets only so long as the signal lasts, such that in the absence of such a signal the stream will remain laminar after leaving the inlet and will discharge into said one outlet.

8. A fluid logic device according to claim 7, including flow steadying ribs disposed in said supply chamber upstream of the inlet to damp out pulsations in the pressure of the stream fluid before it leaves the inlet, thereby to permit use of higher supply pressures than otherwise possible Without exceeding the critical value of Reynolds number at which turbulence occurs.

9. A fluid amplifier comprising a power nozzle for issu- References Cited UNITED STATES PATENTS 1,628,723 5/1927 Hall 137-815 X 2,132,961 10/1938 Morgan ..13839 X 3,001,539 9/1961 Hurvitz 13781.5 3,024,805 3/1962 Horton 13781.5 3,093,306 6/1963 Warren 137-8l.5 3,122,165 2/1964 Horton 13781.5 3,123,900 3/1964 Miller 13839 X 3,144,037 8/1964 Cargill et al. 137--81.5 3,182,674 5/1965 Horton 137-81.5

OTHER REFERENCES A New Solid State Pneumatic Amplifier for Logic Systems, Raymond N. Auget, Automatic Control, December 1962, pp. 24-28.

M. CARY NELSON, Primary Examiner.

S. SCOTT, Examiner.

Claims (1)

1. A FLUID LOGIC DEVICE COMPRISING MEANS DEFINING AN INLET FOR RECEIVING A FLUID POWER STREAM, A WALL ADJACENT ONE SIDE OF THE EXIT END OF THE INLET AND EXTENDING DOWNSTREAM FROM THE INLET, ONE OUTLET INTO WHICH THE STREAM DISCHARGES TO LONG AS IT REMAINS LAMINAR, ANOTHER OUTLET INTO WHICH THE STREAM DISCHARGES WHILE IT IS IN TURBULENT ATTACHMENT WITH SAID WALL, MEANS FOR STEADYING THE PRESSURE OF THE STREAM FLUID AND ASSURING THAT THE STREAM, EVEN IF INITIALLY TURBULENT, WILL BE LAMINAR BEFORE ITS DISCHARGE FROM SAID INLET TO PERMIT USE OF HIGH STREAM FLUID SUPPLY PRESSURE THAT WOULD OTHERWISE CAUSE THE CRITICAL VALVE OF REYNOLDS NUMBER TO BE EXCEEDED AND THE STREAM RENDERED TURBULENT, AND

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