US3503410A - Fluid amplifier - Google Patents

Description

March 31, 1970 G. B. RICHARDS FLUID AMPLIFIER 3 Sheets-Sheet 1 Filed March 16, 1967 zWVWfOF. e 5 54/4 57/ 6'! [bag March 31, 1970 G. B. RICHARDS FLUID AMPLIFIER Filed March 16, 1967 March 31, 1970 I G. B. RICHARDS FLUID AMPLIFIER 3 Sheets-Sheet 5 Filed March 16, 196'? lllllllnulll lllll l ll n lllullllllh NIL W United States Patent O 3,503,410 FLUID AMPLIFIER George B. Richards, P.O. Box 278, Highland Park, Ill. 60035 Filed Mar. 16, 1967, Ser. No. 623,740 Int. Cl. F15c N08 US. Cl. 137--81.5 19 Claims ABSTRACT OF THE DISCLOSURE A fluidic element employing a boundary layer self-attachment principle and/or the Coanada boundary layer wall-attachment principle in which the power jet is an nular and the control fluid exerts control pressure upon a generally annular or cylindrical surface of the power jet to cause the power jet to flow into either a central outlet or a surrounding annular outlet. Various embodiments and variations are presented.

CROSS-REFERENCE TO RELATED APPLICATION George B. Richards application Ser. No. 648,602 filed June 26, 1967 for Fluid Amplifier is a continuation-inpart of the present application.

BACKGROUND OF THE INVENTION Field The invention lies in the field of pure fluid (fluidic) devices, which employ no moving parts, in which a power jet is directed into one of two or more distinct outlets. The field is further refined to devices in which control is effected through pressure of a secondary fluid rather than through the momentum-exchange principle.

Prior art The following are examples of prior art of which applicant is aware: Carlson, Patent No. 3,039,490, June 19, 1962; Horton, Patent No. 3,122,165, Feb. 25, 1964; Horton et al., Patent No. 3,185,166, May 25, 1965; Lewis et al., Patent No. 3,276,423, Oct. 4, 1966.

Fluid Interaction Control Devices, by C. L. Mamzic, delivered at the Fifth National ISA Chemical and Petroleum Instrumentation Symposium, May 5, 1964;

Design GuidePure Fluid Devices, 0. Lew Wood, Machine Design, June 24, 1965;

Fluidics and Fluid Power, by Russ Henke, Machine Design, Nov. 25, 1965;

Focused-Jet Inverter, by Joseph M. Kirshner (paragraph 15.5.4, 238), Fluid Amplifiers, Copyright 1966;

Fluid Element Data Sheet pp. 5-60, Fluid Amplifier State of the Art, Volume I, Research and Development- Fuid Amplifiers and Logic, prepared under Contract No. NAS 8-5408 by General Electric Company, NASA Contractor Report NASA Cr-101, Oct. 1964;

Basic Requirements for an Analytical Approach to Pure Fluid Control Systems, by H. L. Fox and F. R. Goldschmied, Proceedings of the Fluid Amplification Symposium, May 1964, p. 293.

Some of this prior art relates to momentum-exchange devices, which are properly outside the field of the invention, but they are listed to permit a broader understanding of the improvements afforded through the invention.

No representation is made or intended that a search has been made or that no better art is available than that listed.

SUMMARY The fluidic device of this invention improves on those in the prior art by providing considerably faster response in switching, by providing increased stability for the same 3,503,410 Patented Mar. 31, 1970 control pressure when used as a monostable or bistable device, by providing greatly increased frequency of switching when used as an oscillator, and by providing for greatly increased amplification. The invention provides the capability for controlling power jets of greater density for the reason that approximately three times or more of the area of the power jet is exposed directly to the control pressure as compared with a planar device; this capability is further enhanced by the fact that the power jet of this invention needs to be deflected only about one-quarter or less the deflection required for a comparable planar device, and the angle of deflection is accordingly much smaller.

The power jet in the modulated annular jet fluidic ele ment of this invention permits a fluid particle in the power jet to travel in a straight line as compared with the circuitous route required in a focused jet device, for example. This feature reduces the overall losses through the modulated annular element. The two or more axisymmetric outlet ports, a first circular and having its major axis common with the longitudinal axis of the entire element, together with the one or more additional outlet ports represented as successive annuli surrounding said first circular outlet port, require the least deviation from straight line travel of a particle of liquid in a power stream for switching.

The aspect ratio, or the relationship of the power stream annulus diameter to the thickness of a section of this annulus, may be less than unity. The aspect ratio is independent of design considerations other than the quality and the quantity of fluid in the power stream.

The internal and external control annuli provide adequate space for the use of a plurality of control duct connections.

The annular power jet design eliminates the top and bottom plate effect upon the power jet flow.

The design is such that no transition takes place from square to round ducts, which results in a low noise level.

The configuration is such that the envelope dimensions are the smallest possible for a fluid amplifier of the boundary layer self-attachment and/or Coanda wall-attachment class.

Embodiments of the invention themselves to molding in plastics as well as fabrication by the welding of standard metal tubing and tubing fittings with relatively low cost.

These and other advantages are achieve through employment of the boundary layer attachment effect (selfattachrnent and/or wall-attachment) in a fluidic element using an annular power jet which is controlled by a secondary fluid exerting control pressure in an annular area to accomplish switching of the power jet between two or more distinct outlets. The resultant high-speed switching permits more eflicient use as a fluid control element or as a logic element for a computer or numerical control. High-speed switching together with high pressure recovery permit use as a building block in the field of viscous fluid control, for example, and often eliminate the necessity for employment of interface elements.

The various objects of the invention are to provide an improved fluidic device for achieving the various advantages heretofore and hereinafter stated or implied.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of one embodiment of a fluidic device according to the present invention, with parts broken away and in section to illustrate the annular form of the power jet, showing the power jet converging and directed to a central outlet;

FIGURE 2 is a schematic longitudinal sectional view of the fluidic device of FIGURE 1;

FIGURE 3 is a schematic longitudinal sectional view of a second embodiment of fluidic device according to this invention, arranged as a monostable element;

FIGURE 4 is a schematic longitudinal sectional view of a third embodiment of fluidic device according to the present invention, arranged as a bistable element;

FIGURE 5 is a sectional view taken along line 55 of FIGURE 4, illustrating the annular form of the power jet at the point of discharge into the interaction area;

FIGURE 6 is a sectional view taken at the point of discharge of a rectangular power jet into the interaction area of a conventional planar fluidic device, showing a power jet of approximately the same volume as that of FIGURE 5 and illustrating the greatly reduced control pressure area as compared with the annular power jet of FIGURE 5; and

FIGURE 7 is a schematic longitudinal sectional view of a fourth embodiment of fluidic device according to the present invention, arranged as an oscillator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fluidic device of FIGURES l and 2 is generally designated by the reference numeral 10. It comprises a generally tubular outer housing or casing 12 having a tubular inlet portion 14 at one end, and a tubular outlet portion 16 at the other end. The inlet and outlet portions may be arranged at 90 to the central portion as shown, but this is not required, since the inlet and outlet may be arranged in any aligned or angular relationship to one another. The inlet portion 14 has a power jet inlet 18, and the outlet portion 16 has a power jet outlet 20.

A control tube 22 has its inner end portion 24 fixedly secured in radially spaced relation within an inlet section 26 of the tubular casing 12. The outer end portion 28 of the control tube 22 extends out of the tubular casing 12, and the casing is sealed about its juncture with the outer surface of the control tube. An annular passage 30 is formed between the control tube portion 24 and the opposed inner walls of the tubular casing 12 to form an annular power jet. An annular power jet nozzle 32 is formed at the downstream end of the control tube 24. It will be seen that the portion of the fluidic device upstream of the power jet nozzle 32 comprises the inlet section 26.

An outlet tube 34 has its inner portion 36 fixedly secured within the tubular casing 12 with its upstream end spaced substantially downstream of the power jet nozzle 32. The outer end portion 38 of the outlet tube member 34 extends beyond the tubular casing 12 as shown. The tubular casing 12 is sealed about its juncture with the outer surface of the outlet tube 34. An annular power jet passage 40 is provided between the outer portion 36 of the outlet tube 34 and the adjacent inner walls of the tubular casing 12. An internal tubular passage 42 through the outlet tube member 34 provides another outlet passage, With an inner outlet port 44 and an outer outlet port 46. The longitudinal portion of the tubular casing 12 between the power jet nozzle 32 and the inner port 44 of the outlet passage 42 comprises an interaction section 48 of the fluidic device 10. The end portion of the tubular casing 12 downstream of the outlet port 44 comprises an outlet section 50 of the fluidic device.

In this particular embodiment of the invention the annular power jet inlet passage 30 and the annular outlet passage 40 have the same radius for their annular centerlines and the radial thickness of the inlet passage 30- is less than the radial thickness of the outlet passage 40. The power jet may be any fluid, but for purposes of illustration it is considered to be a liquid such as water. The momentum of the power jet causes it to flow out of the outlet passage 40, unless the power jet is subjected to external influences. Thus the annular outlet 40 is referred to as the preferred outlet, and the tubular passage 42 is referred to as the secondary outlet.

The internal passage through the control tube 22 provides a control passage 52, having a control port 54 at its inner end and a control port 56 at its outer end. The control port 56 and the control passage 52 are adapted for being selectively closed by means of a suitable valve, such as the valve disc 58, shown in the open position in FIGURE 2 and in the closed position in FIG- URE 1.

An annular step 60 is provided at the juncture of the inlet section 26 with the interaction section 48 of the tubular casing 12, with the interaction section being larger in diameter. The power jet nozzle 32 is radially aligned with the step 60, as shown. A second control port 62 is formed through the wall of the interaction section 48 immediately downstream of the power jet nozzle 32 and the step 60. A suitable valve is provided for selectively opening or closing the control port 62, such as the valve disc 64, shown in the closed position in FIGURE 2 and in the open position in FIGURE 1.

The annular step 60 is of suflicient depth to accommodate formation of an annular separation bubble 66 where the power jet flow is spaced from the wall as it is ejected from the power jet nozzle 32 into the interaction section 48 when the control port 62 is closed and the control port 56 open, as illustrated in FIGURE 2. The separation bubble 66 is a low pressure area caused by entrainment of the air by the outer surface of the power jet stream, which air cannot be replenished with the control port 62 closed. The internal surface of the power jet in the interaction section also entrains air, but this air is replenished, inasmuch as the control port 56 is open, thus providing pressure of a secondary fluid, air. Hence, the pressure against the internal surface of the power jet is greater, and the pressure differential causes the power jet to diverge and to attach to the inner wall of the interaction section 48 downstream of the annular separation bubble 66. This separation bubble formation and downstream wall atachment is the Coanda boundary layer wall-attachment effect, described quite adequately in the C. L. Mamzic and O. Lew Wood publications listed in the background section of this specification. Thus, with the control port 56 open and the control port 62 closed as shown in FIGURE 2, the entire power jet flows in annular form along the inner wall of the tubular casing 12 out the preferred outlet passage 40 and the preferred outlet port 20.

It should be noted that the control pressure force on the power jet causing it to diverge, as shown in FIGURE 2, is exerted in an annular area represented as a section of a cylinder, providing much more effective control pressure area than is reasonably possible with conventional planar fluidic devices as disclosed in the prior art.

When the control port 56 is closed and the control port 62 is opened, as illustrated in FIGURE 1, the annular separation bubble 66 is eliminated through replenishment of air entering the control port 62, and at the same time, the pressure within the power jet is reduced, since the entrained air cannot be replenished through the now closed control port 56. The pressure within the jet cannot be fully replenished by reverse flow into the outlet passage 42 because the entrained air flowing along with the power jet reduces the flow area, reducing the pressure by the Bernoulli effect. Furthermore, a dynamic pressure loss occurs, since air flowing into the outlet passage 42 must reverse its direction when encountering the entrained air boundary layer. The pressure differential causes the power jet to start to converge. This further reduces the flow area and further increases the pressure differential across the power jet. The effect is cumulative, so that the power jet completely converges in a very short time, a few milliseconds or less if the power jet is a liquid such as water. If the power jet is gaseous, the time of convergence is very much faster. After the jet has converged, the entire power jet flows into the inner outlet port 44 and out the secondary outlet passage 42. This is the condition illustrated in FIGURE 1. In this condition the converging jet adheres to itself, and a separation bubble 68 is formed immediately upstream of the point of convergence. This is not the conventional Coanda wall-attachment effect but might be referred to as a boundary layer self-attachment effect.

As explained, with the parts proportioned generally as shown in FIGURE 2, the outlet 20 is the preferred outlet, and the outlet 46 is the secondary outlet. The power jet will continue to flow out the preferred outlet 20 even if the control port 56 is subsequently closed, as long as the control port 62 remains closed. If both control ports are then simultaneously opened, the power jet will still continue to flow out the preferred outlet 20, since the diameter of the outlet port 44 is smaller than the inner diameter of the annular power jet nozzle 32, and the length of the interaction section 48 is not sufiicient to permit the jet to deteriorate.

On the other hand, if the power jet is flowing out the secondary outlet 46 with the control port 56 closed and the control port 62 open, as in FIGURE 1, the power jet will tend to diverge if the control port 56 is subsequently opened, even if the control port 62 remains open, because the fluid ejected from the nozzle 32 tends to follow a straight line unless it is caused to converge or diverge because of a pressure diiferential. Hence, the power jet will switch to the primary outlet 20, although not as fast and without the positive action which occurs if the control port 62 is closed.

Although the outlet port 20 is the preferred outlet in the configuration of FIGURE 2, the flow will continue out the secondary outlet 46 as shown in FIGURE 1 even if the control port 62 is subsequently closed as long as the control port 56 remains closed. This is because sufiicient replenishment air will flow in the primary outlet 20 so that a pressure differential still remains, although reduced, keeping the power jet in converged form. However, if the control port 56 is then opened, the power jet flow will almost instantly switch from the secondary outlet 46 to the primary outlet 20 because the pressure differential is suddenly reversed due to replenishment of entrained air within the annular jet through the control passage 52; the jet will immediately attach to the wall of the interaction section 48 because of the Coanda effect.

The longitudinal position of the outlet tube 34 may be made adjustable externally in order to vary the axial length of the interaction section 43. This may be accomplished, for example, by providing a suitable threaded, sealed connection (not shown) between the outlet tube 34 and its juncture with the casing 12 such the outlet tube may be turned in or out to change the axial position of the inner outlet port 44. Such adjustability may be provided to accommodate power jets of differing viscosity, rates of flow, and pressures. Furthermore, by increasing the axial length of the interaction section 48 sufiiciently, the outlet passage 42 can be made the preferred outlet and the annular outlet passage 40 the secondary outlet; this results from the inherent tendency of a free annular jet to converge at a sufficient distance downstream of the ejection nozzle. It should be under stood that adjustment of the length of the interaction chamber may be made while the device is in operation to accomplish these results.

The embodiment of FIGURE 3 is a monostable fluidic device. This device is generally designated by the reference numeral 70 and includes an outer casing 72, a control tube '74, and an outlet tube 76; these correspond to the casing 12, the control tube 22, and the outlet tube 34, respectively, of the embodiment of FIGURES l and 2. The device includes an inlet section 78, an interaction section 80, and an outlet section 82. The power jet enters the casing 72 through an inlet port 84 and leaves the device through either a primary outlet 86 or a secondary outlet 88. The power jet takes an annular form as it passes through an annular passage 90 in the inlet section 78 and is ejected in annular form into the interaction section from an annular power jet nOZZle 92 at the juncture between the inlet section and the interaction section. A control port 94 is formed at the outward end of the control tube 74 and is adapted to be selectively opened or closed by suitable valve means such as a valve member 96. When the valve member 96 is closed as shown in FIGURE 3, the annular power jet entering the interaction section 80 is forced to converge, and a separation bubble 98 is formed immediately upstream of the point of convergence. The converging jet thus adheres to itself through the boundary layer self-attachment effect. The converged jet flows into an inner outlet 100 in the outlet tube 76 and thence out the secondary outlet 88.

If the control port 94 is opened, the air pressure within the power jet is replenished, and the separation bubble 98 disappears. Since the pressure differential thus disappears, the momentum of the jet causes it to diverge and to fiow into an annular outlet passage 102 and out the primary outlet 86. A relatively deep step 103 is formed at the juncture of the inlet section 78 and the interaction section 80. The depth of the step is such that the wall of the interaction chamber is spaced radially outwardly a sutficient amount to prevent the power jet from attaching to the wall; in other words, there is no Coanda wallattachment in this embodiment of the invention.

The fluidic device 70 of FIGURE 3 is monostable because the power jet will always flow out of the preferred outlet 86 unless the control port 94 is closed. No additional control port is required for controlling the path of the power jet. Switching between the preferred outlet 86 and the secondary outlet 88 and vice versa is accomplished in milliseconds, depending upon the nature of the fluid of the power jet, by opening and closing the control port 94.

It will be understood that the length of the interaction chamber 80 may be made adjustable (not illustrated) in the manner indicated in connection with the embodiment of FIGURES 1 and 2 for the purposes explained in connection with that embodiment.

A third embodiment of fluidic device according to the present invention is illustrated in FIGURE 4. This device, which is generally designated by the reference numeral 110, is a bistable or flip-flop element. It includes an outer casing 112, a heavy-walled control tube 114, and an outlet tube 116. The casing is provided with a power jet inlet port 118 and a power jet outlet port 120. Another outlet port 122 is formed at the outer end of the outlet tube 116. A control port 123 at the outer end of the control tube 114 controls secondary control flow in an axial passage 124 connected to a radial control passage 125. A second control port 126 is formed through the wall of the casing 112 immediately downstream of a step 127. Flow into the control port 123 is controlled by means of a valve 128, and flow through the control port 126 is controlled by means of a valve 130.

The power jet enters the device through the inlet port 118 and is rendered annular in an annular passage 132 between the outer surface of the control tube 114 and the inner surface of the casing 112. As in the case with the previous embodiments, the device comprises an inlet section 134, an interaction section 136, and an outlet section 138. The axial length of the interaction chamber 136 may be adjustable (not shown) for the purposes indicated in connection with the embodiments of FIG- URES l, 2, and 3.

The power jet is ejected into the interaction section 136 through an annular nozzle 140 formed at the juncture of the inlet section and the interaction section at the step 127. From here the power jet exits through a central outlet passage 142 through the outlet tube 116 and the outlet port 122, or it is directed into an annular outlet passage 144 and is ejected out the outlet When the control port 123 is closed and the control port 126 is open, as illustrated in FIGURE 4, the power jet converges and flows out the outlet 122. This results from the Coanda effect causing formation of an annular separation bubble 146 immediately downstream of a step 148 formed in the control tube 114 toward its inner end, radially inwardly from the power jet nozzle 140. Immediately downstream of the separation bubble 146 the power jet flow reattaches to the surface of a nose portion 150 at the inner end of the control tube and thus flows into an annular opening 152 formed at the end of the nose section 150 and the entrance to the central outlet passage 142. From here the flow continues to converge, forming a central separation bubble 154 immediately upstream of the point of convergence. This second separation bubble 154 is formed as a result of the boundary layer self-attachment effect referred to in connection with the first two embodiments.

If the control port 123 is opened and the control port 126 is closed, the power jet flow switches almost instantly from the outlet 122 to the outlet 120, as a result of the external Coanda effect and the elimination of the separation bubbles 146 and 154 when the pressure is replenished through the open control port 123.

The fluidic device 110 is bistable because neither outlet 120 nor outlet 122 is preferred. The flow will not switch if the one open control port is subsequently closed as long as the other control port remains closed, regardless of which outlet is being utilized. Hence, the flow will continue out the outlet 122 as shown in FIGURE 4 even though the control port 126 is subsequently closed, as long as the control port 123 remains closed. By the same token, the flow will continue out the outlet 120, when it is flowing out that outlet, even though the control port 123 is subsequently closed, as long as the control port 126 remains closed. Thus the flow will continue out one outlet indefinitely until the control port controlling the formation of a separation bubble is opened while the other control port is closed. In this case the flow switches almost instantaneously, in a matter of milliseconds or less, depending upon the viscosity and density of the fluid of the power jet. Here again the formation of and elimination of annular separation bubbles and annular pressure areas on opposite sides of the jet drastically increase the speed of switching, increase the stability of flow in one state or the other, and reduce the pressure required for adequate control.

The annular form of the power jet according to the present invention is compared with the rectangular form of the power jet in a conventional planar fluidic device in FIGURES and 6, respectively. Both of these cross-sectional views are taken at the point of ejection of the power jet into the interaction section of the respective fluidic elements, with the power jets being of approximately the same cross-sectional area and with the height of the rectangular jet approximately equal to the outside diameter of the annular jet. In this comparison the effective area subjected to control pressure is over three times as great with the annular power jet of FIGURE 5 as it is with the rectangular power jet of FIGURE 6. The relative difference varies, of course, with different configurations, but the effective control pressure area for an annular power jet is always must greater than the control pressure area for a conventional rectangular jet.

A fourth embodiment of fluidic device according tothis invention is illustrated in FIGURE 7 in the form of a fluidic oscillator, generally designated by the reference numeral 160. The fluidic oscillator 160 includes a casing 162, a heavy-walled control tube 164, and an outlet tube 166.

Power jet flow enters through an inlet port 168 and exits through either an outlet port 170 or an outlet port 172, the former formed in the casing 162 and the latter in the outlet tube 166. The device is divided into an inlet section 174, an interaction section 176, and an outlet section 178. An annular power jet nozzle 180 is formed at the inner end of the control tube 164 at the juncture between the inlet section and the interaction section. From the interaction section the flow passes into an inner outlet port 182 directing flow out the outlet 172, or into an annular outlet 184 directing flow out the outlet 170.

In this embodiment of the invention the control tube 164 is not provided with an external control port but instead has an axial control passage 186 connected to a closed control loop 188 which terminates with a dynamic inlet 190 located in radially spaced relation within the outlet port 182, making the outlet port 182 annular as shown.

When the power jet is started, it first flows through the annular passage 184 out the outlet 170. Entrainment of air within the jet reduces the air pressure and causes it to converge until it enters the annular outlet port 182 and thence out the outlet 172. As it converges further, a portion of the control jet enters the dynamic port 190 and flows into the control loop 188, such that a pressure wave front 192 travels in a counter-clockwise direction as shown in FIGURE 7. The pressure wave front provides pressure of a secondary fluid, in this instance partly air and partly water. As this pressure wave front completes the loop through the axial control passage 186 and is ejected into the interaction section 176 within the power jet, it temporarily satisfies a separation bubble 194 which was formed as a result of the boundary layer self-attachment principle. This increases the pressure within the ananular power jet so that the jet switches again to the outlet 170. At this point the cycle starts over again, causing the jet to converge until flow through the control loop causes it to diverge again. This oscillating action continues as long as the power jet flow continues. In this embodiment the control is thus achieved through the control loop 188 and the dynamic inlet 190 instead of through valve means as in the previous embodiments.

With a fluidic device 160 as shown in FIGURE 7, the oscillations are in the nature of 500 cycles per second when the power jet is comprised of Water. A comparable planar device with a water power jet can achieve only a fraction of this number of oscillations, in the nature of approximately cycles per second. If the power jet is gaseous, the oscillations will be in the order of 40,000 cycles per second as compared to approximately 10,000 cycles per second as might be expected with a comparable planar type fluidic oscillator using the same gaseous medium for the power jet.

As with the previous embodiments, the operational characteristics of the FIGURE 7 embodiment can be modified by providing suitable means (not shown) for externally changing the length of the internal section 176. In such an adjustable oscillator device the length of the interaction section 176 is set at an optimum value for a particular usage. Adjustment which shortens the length of the interaction changer, within limits, reduces the frequency of oscillations. Lengthening the interaction section increases the frequency, again within limits. By providing adjustability the oscillator device can also be adapted for use with different fluids.

It should be understood that while the word annular has been used to describe the form of the power jet in the foregoing description, this word is used in a broad sense to include not only areas of strictly circular crosssection but other tube-like shapes, such as those of generally oval or polygonal cross-section. Ordinarily the power jet takes a circular annular cross-sectional shape, but the invention is not so restricted. However, in every instance according to the present invention, the power jet is ejected into the interaction chamber in tube-like form with all elements of the flow initially parallel to the axis of symmetry, as distinguished from so-called focused jets of the prior art. It is intended that annular be construed in the sense indicated in both the specification and the claims.

I claim:

1. In a fluidic element, the improvement comprising means for forming a tube-like annular power jet of fluid confining a space within said jet for interaction of said fluid;

oscillatory control means actuated by said power jet for causing alternate convergence and divergence of the power jet,

a central outlet passage which receives the flow of said power jet when converged, and

a surrounding annular outlet passage which receives the flow of said power jet when diverged.

2. A fluidic element according to claim 1 in which said oscillatory control means comprises a two-ended passage having one end communicating with the space within said annular power jet and having its other end disposed as a dynamic inlet facing downstream in said central outlet passage.

3. In a fluidic element according to claim 1, the improvement comprising means for adjusting the distance between said power jet forming means and said outlet passages for changing the oscillatory operational characteristics of the fluidic element.

4. In a fluidic element having an inlet for receiving a power jet of fluid, the improvement comprising:

means including said power jet fluid for defining an enclosed space devoid of physical structure;

first control inlet means opening into said enclosed space for selective convergence of said power jet fluid into a solid stream by boundary layer selfattachment of said power jet fluid.

5. The combination according to claim 4 in which:

at least a portion of said enclosed space constitutes a hollow fluid interaction cavity;

and further in which said control inlet communicates with said enclosed space upstream of the point of convergence of said power jet.

6'. The combination according to claim 5 and further including:

a pluralitj of power fluid outlet ports positioned a predetermined distance downstream of the point of communication of said control inlet.

7. The'combination according to claim 6 and further including:

fluid forming means for projecting said power jet fluid into said enclosed space only in a direction parallel to the central axis of said enclosed space.

8. The combination according to claim 7 and further including:

control means for alternatively closing said first control inlet and coupling said first control inlet to a secondary fluid source, whereby closure of said control inlet causes a low pressure condition within said enclosed space by entrainment of said secondary fluid with said power jet fluid for converging said power jet fluid into a solid stream.

9. The combination according to claim 8 and further including:

wall means extending between said inlet and outlet means and spaced transversely outward of the path of said fluid power jet flow.

10. The combination according to claim 9 and further including:

control means comprising a second control inlet normally communicating with a tertiary control fluid source, for controlling selective attachment of said power jet fluid with said wall means.

11. The combination according to claim 10 in which:

said power jet fluid normally flows into a predetermined one of said outlet ports, absent closure of either of said control inlets;

and further including adjustment means for varying said predetermined distance between at least one of said outlet ports and said first control inlet opening to shift said normal power jet fluid flow to a different one of said outlet ports.

12. The combination according to claim 11 in which:

said first control inlet communicates with said enclosed space in a downstream direction.

13. A fluid device, for utilizing a power jet of fluid, consisting essentially of:

fluid inlet means; a plurality of fluid outlet ports spaced a predetermined distance from said inlet means; and means including said power jet fluid for defining an enclosed space devoid of physical structure, intermediate said inlet means and said outlet means, having a central axis, said means further including a control inlet communicating with said enclosed space and alternatively providing and cutting off the flow of a secondary fluid to said enclosed space for selectively converging said power jet fluid from opposite sides of said central axis into a solid stream by a boundary layer self-attachment effect. 14. A fluidic device having an inlet, an interaction and an outlet zone, comprising:

inlet means within said inlet zone for developing an annular power jet and for projecting said annular power jet into said interaction zone, said annular power jet defining, within said interaction zone, a confined space devoid of physical structure; first control means including a control fluid conduit opening into said confined space for normally providing control fluid flow thereto to replace that entrained by said annular power jet but adapted for restricting control fluid flow to said confined space to selectively converge said annular power jet into a single stream by boundary layer self-attachment of the fluid of said annular power jet; and outlet means within said outlet zone comprising a plurality of separate outlet channels for collecting said power jet fluid flowing from said interaction zone. 15. In a fluidic element according to claim 14, the improvement comprising means for adjusting the distance between said power jet forming means and said outlet passages for changing the operational characteristics of the fluidic element. 16. In a fluidic element according to claim 14, the improvement comprising second control means for selectively applying and cutting ofl pressure of said secondary fluid to an external annular area of said power jet downstream of said inlet means; whereby said power jet converges when said second control means supplies pressure of said secondary fluid while said first control means cuts off pressure of said secondary fluid, and whereby said power jet diverges when said first control means supplies pressure of said secondary fluid while said second control means cuts off pressure of said secondary fluid. 17. In a fluidic element according to claim 14, the improvement comprising a central outlet passage which receives the entire flow of said power jet when said second control means supplies pressure of said secondary fluid while said first control means cuts oif pressure of said secondary fluid, and surrounding annular outlet passage which receives the entire flow of said power jet when said first control means applies pressure of said secondary fluid while said second control means cuts off pressure of said secondary fluid. 18. A fluidic device having an inlet, an interaction and an outlet zone, comprising:

inlet means within said inlet zone adapted for developing power jet fluid flow of predetermined crosssectional configuration with portions of said power jet fluid lying on opposite sides of a predetermined axis of said inlet means and for projecting said power jet fluid into said interaction zone with said predetermined cross-sectional configuration;

means within said interaction zone and including said power jet fluid for defining a confined space devoid of physical structure; control means including a control fluid inlet opening into said confined space for normally providing control fluid flow thereto to replace that entrained by said power jet fluid but adapted for restricting control fluid flow to said confined space to selectively converge said power jet fluid into a single stream by boundary layer self-attachment of said power jet fluid; an outlet means within said outlet zone comprising a lurality of separate outlet channels for collecting said power jet fluid flowing from said interaction zone. 19. The fluidic device of claim 18 and further including means for adjusting the distance between said inlet means and said outlet means for varying the operational characteristics of said fluidic device.

References Cited UNITED STATES PATENTS Carlson l3781.5 Bliss et al 13781.5 XR

Palmisano 1378l.5

Jones 137-815 XR Boothe l3781.5 Lewis et al. 137-81.5 XR Bjornsen et a1 13781.5 Swartz 13781.5

SAMUEL SCOTT, Primary Examiner

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