US3420253A

US3420253A - Fluid jet amplifier

Info

Publication number: US3420253A
Application number: US462762A
Authority: US
Inventors: William S Griffin
Original assignee: National Aeronautics and Space Administration NASA
Current assignee: National Aeronautics and Space Administration NASA
Priority date: 1965-06-09
Filing date: 1965-06-09
Publication date: 1969-01-07
Anticipated expiration: 1986-01-07

Description

Jan. 7, 1969 United States Patent O 3,420,253 FLUD JET AMPLIFER William S. Griffin, Lakewood, Ohio, assigner to the United States of America as represented by the administrator of the National Aeronautics and Space Administration Filed .lune 9, 1965, Ser. No. 462,762

ABSTRACT F THE DISCLOSURE A fiuid amplifier including a jet, an interaction region and a receiver. Vent means are provided for the interaction region. Receiver outlets are connected to the interaction region through a receiver intermediate passageway and a receiver inlet passageway which are out of alignment with one another. A vent passageway which is in alignment with the receiver intermediate passageway is provided to receive reverse fiuid flow from the receiver.

The invention described herein was made by an employee of the United States Government and may lbe manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The instant invention relates to fluid systems. More particularly, the instant invention relates to an improved fluid jet amplifier.

A fluid jet amplifier as described herein is a no moving parts device which is capable of amplifying fluid signal fiows and pressures in much the same manner as its electrical equivalent, the transistor, amplifies currents and voltages. A tiuid jet amplifier can utilize either a liquid, a gas, or a combination thereof.

Basically, a iiuid jet amplifier is a device wherein an input fiuid fiowing through a nozzle forms a jet which is caused to iiow through an interaction region or cavity wherein the jet may be defiected to one side or another of said region by means of pressures developed in the interaction region by the iiow fluids established therein and/or the use of control signals or nozzles located on either side of the jet. Introducing fiow at one of the control nozzles causes the cavity pressure on that side of the jet to be raised thus causing the jet to deiiect to the other side. Effectively capturing and utilizing the output flow from the iiuid jet amplifier is much more diicult than loading a transistor. The usual method consists of placing a pair of receivers immediately downstream of the interaction or cavity region.

In fluid jet amplifiers of the type described herein various problems have been encountered which can greatly effect its performance.

One problem involves the furnishing of a fiow restriction lbetween the control line and the cavities of the interaction region of a bistable amplifier. For a Coanda effect iiuid jet amplifier to be bistable in operation, some type of restriction must be provided. One method consists of placing an oril'ice restriction in the control lines leading to the interaction region. The volume in the control signal lines between the orifice restriction and the interaction region can be large in comparison to the volume of the cavities in the interaction region, can reduce switching speeds and cause transient instabilities to occur during switching. It has also been proposed to form the proper orifice restriction by having a control port of narrow width located in close proximity to the side wall of the main jet. However, for the amplifier to have high triggering sensitivity, the sidewalls must be set back from the main power nozzle a small and precisely controlled amount. Inasmuch as the performance of the amplifier is quite 3,420,253 Patented Jan. 7, 1969 ICC sensitive to the amount of the sidewall setback, small manufacturing errors can cause variations in the amplifier performance. Furthermore, a fairly large control signal flow may be demanded even in the absence of a control pressure signal. This quiescent control flow must be taken into account in the design of fluid jet amplifiers. Failure to take this control fiow into account can result in inadvertent switching of the amplifier.

Another problem is that the reverse fiow exiting from one of the receiver channels toward the interaction region can cause a change in the amplifiers performance. Such a situation is likely to occur if the receivers are connected to a moving piston or if they are connected to a large volume and the jet is suddenly switched from one side to another. Also, lblockage or restriction of the receiver output fiow can sometimes cause unstable operation. It has been proposed to put a plurality of bleeds in the load. However, this can cause great losses in power. Other proposed solutions include putting a cusp on the splitter in order to create a stabilizing vortex and drilling a hole in the receiver channel at a right angle to the plane of the amplifier. However, this latter method will also cause low power recovery.

It is therefore an object of the instant invention to reduce the sensitivity of a fiuid amplifier to receiver reverse flow.

It is another object of the instant invention to provide for a fluid amplifier that is stable under all load conditions.

It is still another object of the instant invention to provide for an improved duid amplifier that will maintain good pressure and flow recoveries and at the same time be stable under all load conditions.

It is still another object of the instant invention to provide for an improved fluid amplifier wherein the receiver reverse ow is prevented from changing the control pressure and fiow required to switch said amplifier.

It is yet still another object of the instant invention to eliminate using large safety factors in computation of control pressures and flows in fiuid amplifiers.

It is another object or" the instant invention to provide for a fluid amplifier that can be used with a piston type load.

It is another object of the instant invention to reduce the control flow required in the absence of controlled pressure signal in a fiuid amplifier.

It is still another object of the instant invention to provide a fiuid jet amplifier which requires low control signal pressures and fiows and which `does not require a small, precisely controlled wall offset at the beginning of the interaction region.

It is another object of the instant invention to provide for a tiuid amplifier having large deflection angles and a short interaction region length.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed ydescription when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein FIG. l is a schematic elevational section view of one embodiment of the instant invention and FG. 2 is an enlarged view of the portion of the device shown in FIG. 1 enclosed within the dotted line.

In accordance with this invention the aforesaid and other objects are achieved by `designing a fiuid amplifier wherein an effective orifice restriction is formed by the edge of the control port with the main jet stream. The control ports or nozzles are located upstream from the interaction region. In addition, the receiver channels are designed so that the mouth of the channels are displaced laterally and pointing away from the interaction region.

The receiver section of the amplier is further provided with a baffle wall to separate the receiver reverse flow from the entrainment ow to the interaction region of the iiuid jet ampliiier.

Referring now to the drawings wherein like reference numerals represent like parts there is shown in FIGS. 1 and 2 a uid amplifier comprising a substantially solid body 10. iIn the embodiment shown the solid body is fabricated from a transparent plastic. However, any other suitable material possessing suitable `strength Such as ceramics, opaque plastics, or metals may also be employed. The solid body 10 is provided with a plurality of channels or passage ways through which a fluid may flow. These passageways are either cut, etched or otherwise suitably formed therein. The completed fluid amplifier also includes a cover plate (not shown) which may be fabricated from any of the above-mentioned materials. The cover plate is fastened in a Huid-tight relationship to the solid body by means of screws (also not shown). However, any other type of sealing means such as cement may be employed. In FIG. l the holes 21 for receiving the screws or other similar fasteners are shown suitably spaced about the solid body.

The solid body member 10 is comprised basically of three parts. Namely a power and control inlet section, van interaction region, and a receiver section.

The power and control inlet section includes a primary fluid supply port 31 through which a compressor or pump (not shown) supplies a suitable regulated stream of uid into ra primary uid input chamber 32. A plurality of guide vanes 33 in the form of projections are located within the iiuid input chamber 32 to aid in directing and smoothing the stream of fluid into a power nozzle 34.

A pair of secondary

uid supply ports

41, 42 are located on either side of the main power nozzle 34. These

secondary ports

41, 42 introduce control signal pressures and flows into their respective connecting control port channels 43, `44. The control port channels 43, 44 in turn connect respectively to .a pair of

control inlets

45, 46 positioned adjacent to the main power nozzle 34 and the main power stream. Said

control inlets

45, 46 introduce control ow into the interaction region through an orifice restriction I51 formed by the edge of the

control inlets

45, 46 land the main jet power stream. The walls of the

orifices restriction

52, 53 are in substantial align-ment with the walls of the main power nozzle 34. The length of the orifice restriction l51 is sized so as to be either equal to or less than one half the width of the main power nozzle 34. This method of providing an orifice restriction enables control flow to be introduced into an interaction region with only a small control pressure and reduces the quiescent control iiow demanded by the interaction region when no control pressure is present. The interaction region or section includes an interaction region chamber 61. As shown in FIGS. 1 and 2 the interaction region chamber 61 is formed by a plurality of

sidewalls

62, 63, 64, 65 and a pair of interaction region backwalls 66, 67. Interaction region sidewalls 62, 63 are bent at an angle equal to the angular deiiection of the main power jet. A pair of interaction region vents 71, 72 are in communication with the interaction region chamber `61 and furnish entrainment ow at ambient pressure to the interaction region. These interaction region vents 71, 72 in turn exit by means of a pair of interaction region vent ports 73, 74 connected to exhaust pressure.

A receiver section or portion is located immediately downstream of the interaction chamber. The receiver portion includes a pointed divider member 81 located immediately downstream of the interaction region chamber 61. The divider member 81 includes a centrally disposed an axis substantially parallel to the interaction region sidewalls 62, 63. The receiver connecting inlet passages 84, 85 in turn exit into a pair of receiver

intermediate passage ways

86, 87 at a shallow angle (20 in FIG. 1). The receiver intermediate passages, 86, 87 are displaced laterally from the interaction region 61 and angled such that yany reverse flow from them will completely miss the interaction region 61. Because the reverse flow completely misses the interaction region 61, changes in interaction region performance as -a result of receiver reverse ow are reduced. By means of this angle between the receiver connecting inlet passages 84, 85 and the receiver

intermediate passages

86, 87, any receiver reverse ow can be directed away from the interaction region 61.

To further prevent any receiver reverse flow from either returning to the interaction region chamber 61 `or interfering with entrainment iow to the interaction region 61, a pair of receiver vents 91, 92 are located on either side of the receiver connecting inlet passages 84, 85. The receiver vents 91, 92 are in the form of channels which are in substantial alignment with the reeciver intermediate passage ways and which terminate in

receiver vent ports

93, 94. Each area bounded by a receiver vent 91, 92, its adjacent receiver connecting inlet passage 84, `85 and its adjacent interaction region vent 71, 72 forms a

baie wall

95, 96. By means of the receiver Vent 91, 92 in cooperation with the

bafe wall

95, 96, any receiver reverse iiow will be prevented from travelling down into the receiver connecting inlet passageways 84, 85 or interfering with entrainment flow delivered to the interaction region. This flow pattern is shown schematically by arrows in the channels 'of FIG. 1. The receiver

intermediate passageways

86, 87 in turn exit into a pair of diffuser sections 88, 89 lwhich in turn exit into a plurality of

receiver outlets

101, 102, 103, 104, 105, 106 which may be connected into a plurality of arbitrarily chosen loads, such as the control ports of other iiuid jet ampliers, Volumes, pistons, bellows, or positive displacement motors.

An amplifier according to the instant invention has been built and tested. Execellent results were obtained with the following power nozzle (34), interaction region (61) land receiver dimensions:

Power nozzle width 31--D5 Spacing between interaction sidewalls 64, 65-2.2Dj

Length `of interaction region sidewalls 6-4, 65-2.2DJ

Length of exit portion of interaction region sidewalls Angle of receiver inlet passages 84, 85-20" Width of center vent port Y83-.813DJ Width of receiver inlet passages 84, 85-1.3Dj

Width of receiver intermediate passages 86, 87-1.3Dj

Width of interaction region vents 71, 72-J813D3 Width of

control ports

45, 46-.813DJ With an amplifier of the above-listed specifications, average control pressures and flows of 7 pecrent and 5 percent of supply pressures and flows, respectively, were required to switch the power jet. Increasing the control pressure by 60 percent enabled the power jet to be switched into a reverse iiowing receiver pressurized at 40 percent of the supply pressure to the main power noLzle 31.

The yaforesaid performance gures were obtained with an amplier having a throat width of .040 and a supply pressure of 1.0 p.s.i.g. The limits on range of pressures were determined by a maximum throat Mach number of .8 and a minimum throat Reynolds number (based on throat width, Dj) of 4000. The ratio of depth of the amplitiers channels to throat width was 1.5.

Obviously many modifications and Variations of the present invention are possible in the light of the above teachings. It is therefore to be understood, that within means in communication with the power inlet means for controllably deliecting said stream of uid under pressure, an orifice restriction in communication with the power inlet means and located downstream of the control inlet means, an interaction chamber in communication with the oriiice restriction and located downstream from said oriiice restriction, interaction region vent means in communication with the interaction region chamber for furnishing entrainment flow to said interaction chamber and receiver means positioned downstream of the interaction chamber, said receiver means including receiver vent means for providing a path thereby for receiver reverse flow.

2. The invention according to claim 1 wherein said power inlet means includes a power nozzle and wherein said orifice restriction is in substantial alignment with said power nozzle.

3. The invention according to claim 2 wherein the length of the oriiice restriction is one-half the width of the main power nozzle.

4, The invention according to claim 1 wherein said receiver means includes a receiver connecting inlet passage way in communication with the interaction chamber downstream of the interaction region vent means and an intermediate passage way for connecting the receiver inlet passage Way into a receiver outlet, said receiver inlet passage way being out of alignment with the receiver intermediate passage way and said receiver vent being in alignment with the receiver intermediate passage way.

5. The invention according to claim 4 wherein said receiver inlet passage way intersects the receiver intermediate passage way at an angle of approximately 20 degrees and wherein said receiver vent passage way and said receiver intermediate passage way form an angle of approximately 180 degrees.

References Cited UNITED STATES PATENTS 3,122,165 2/1964 Horton 137-815 3,187,763 6/1965 Adams 137-815 3,209,775 10/1965 Dexter et al 137-815 3,225,780 12/1965 Warren et al 137-815 3,261,372 7/1966 Burton 137-815 3,269,419 8/1966 Dexter 137-815 3,270,758 9/1966 Bauer 137-815 3,282,281 11/1966 Reader 137-815 FOREIGN PATENTS 1,329,569 5/ 1963 France.

SAMUEL SCOTT, Primary Examiner.