HDL-SR-83-9

August 1183

FL U/DIGS

.1j

Basic Componentsand Applications

by James W. Joyce D

U.S. Army Electronics Researchand Development Command

Harry Diamond Laboratories

* * Adelphi, Maryland 20783

Approved for public release; distribution unlimited.

U s83 10 24 053

The findingo In this report are not to be Cunetruid as an official D•eprtmefntof the Army position unlese so designated by other authorized documents.

Citation of manufacturers' or trade names don not constitute an officialIndorsement or approval of the use thereof.

Destroy this report when it Is no longer needed. Do not return it to theorgttor.

Pruvylus editions of this repoit wereissued as HDL.SR.T74 (October 1977)and HDL-SR-79. (September 1979).

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HDL-SR-83-9 lA. flTLEK (and Subtitle) Zrp rPaoTaPn oa

Fluldics-Basic Components and Applications Special ReportS. PERFORMING oRal REPORT NUMBER

7. AUTH0R(o) G. CONTRACT OR GRANT NUMBER(*)

James W. Joyce PRON: 1 F3ROOO1O01 FA9

a. PERiORMING ORGANIZATION NAME AND ADDRESS WC PROGRAM ELEMNT. PROJECT, TASKAREA I WORKUITNMIRHarry Diamond Laboratories A9 XUI UMR

2800 Powder Mill Road Program element: 61 102AAdeiphl, MD 20783

11. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATEU.S. Army Materiel Development August 1983and Readiness Command 1S. NUMBER OF PAGES

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19.' SUPPLEMENTARY NOTES

Previous editions of this report were Issued as IADL-SR-77-6 (October 1977) and HDL-SR-79-6(September 1979).

DA Proj: 1 L161 102AH44 HDL Project: A41334 DRCMS Code: 611 1021-440011It. KEY WOROS (Continue an toVM9@ side Itfnecessay and identify by block nutua e)

Fluidics Proportional amplifiers Fluid controlFluerIcs Sensors Laminar proportional amplifierBistable devices Laminar flow Lamintdr jet angular rate sensor

i2l. AuSTRACr (Clow~how m moerse ah N ad sawmo d Ideatifr by' block rnumabor)

Since Its discovery at Harry Diamond Laboratories In 1959, fluidics has gradually beendeveloped Into a viable technology. This report provides a description of fluidic components andsystems now In use or ready for use In many applications. The fluidic technology provid~es sens-Ing, computing, and controlling functions with fluid power through the Interactions Iof fluidstreams. Since fluidics can perform these functions without mechanical moving parts that willwear out, It has the advantages of simplicity and reliability. Other advantages discussed are thelow cost, environmental Insensitivity, and safety of fluidic systems.

DD43 mIOO I NOV55" ISOU3L UNCLASSIFIED1SECURITY CLAWSPICATfOR OF THIS P'AgE (mome Does Xntered)

*..............2...

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20. Abstract (Cont'd)

Commercial applications of fluldics are found in the aerospace Industry, industrial control,medicine, and personal-use items. The first aerospace application in production in the UnitedStates was for the thrust-reverser control for a DC-10 airplane. In industry, fluidics has been ap-plied to air-conditioning controls, machine controls, process controls, and production-line con-trols. More than 100 different applications have been identified In these areas,

One of the first commercial applications of fluidics was for life-support medical equipment.Several medical devices now on the market Incorporate some degree of fluidic control. Personal.use fluidic products Include pulsating showerheads, lawn sprinklers, and oral irrigators.

For military use, fluidics has been successfully applied to a fluidic generator to convertpneumatic energy into electrical energy, a fluidic stability augmentation system for helicopters,and a pressure-regulating system for aircraft. Currently under development are rate sensing cir.

cults for roll rate control of cannon-launched guided projectiles and missiles, and a fluidiccapillary pyrometer for continuous temperature measurements in high-temperature processcontrol.

,A ession ?For

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Availability Codes

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Contents

Page

1. INTRO DUCTIO N .............................................................................................................................. 5

2. FLUIDIC CO M PO NENTS .............................................................................................................. 5

2.1 Fluidic Sensors and Interface Devices .................................................................. 62.2 Fluidic Amplifiers .................................................. 7

2.2.1 Jet-Deflection Amplifiers .......................................................................................... 82.2.2 Wall-Attachm ent Amplifiers ...................................................................................... 92.2.3 Impact Modulation Amplifiers ........................................ 102.2.4 Flow Mode Control Amplifiers ........................................ 102.2.5 Vortex Flow Amplifiers ............................................................................................. 11

3. ADVANTAG ES O F FLUIDICS .................................................................................................... 11

4. CO M M ERCIAL APPLICATIO NS O F FLUIDICS ....................................................................... 12

4.1 Aerospace ............................................................................................................................... 124.2 Industrial Control ................................................. 124.3 M edicine ................................................................................................................................ 15

S 4.4 Personal-Use Item s ............................................................................................................ 15

5. M ILITARY APPLICATIO NS O F FLUIDICS ................................................................................ 16

6. CONCLUSIO NS ............................................................................................................................. 18

LITERATURE CITED ................................................................................................................................ 20BIBLIOGRAPHY ..................................................................................................................................... 21

Figuresbe.S..-

1. Turbulent and lam inar jets ........................................................................... I'll.. .... ... ......... 62. Fluidic hardware .................................... ........ . ....... 63. Som e typical C form at configurations ............................................................................................. 74. Silhouette of fluidic LJARS .............................................................................................................. 75. Schem atic diagram of basic fluidic am plifier device ........................................................................ 86. Jet-deflection fluidic proportional am plifier .............................................................................. 87. Silhouette of HDL standard LPA ....................................................................................................... 98. W all-attachm ent fluidic bistable am plifier ........................................................................................ 99. Transverse Impact m odulator ....................................................................................................... 10

10. Flow m ode control amplifier ......................................................................................................... 10

3

Contents (Cont'd)

Page

11, V o rtex flow a m p lifie r ......................................................................................................................... 1112. Fluidic thrust-reverser control system ........................................................................................... 13

13. Fluidic air-conditioning controller ........................................... 1414. Fluidic dIverter valve ................. ..................... ............... ............................. 1415 . F lu id ic co ntro lle r .............................................................................................................................. 1516. Fluidic pulsating showerhead ................................................ 1517. Fluidic generator ...... .......................................... ...... 1618, Fluidic single-axIs stability augmentation system ........... . ................................ ...... 16

"19. Fluidic pressure-regulating system ............................................. 1720. Fluidic rate-sensing hardw are ....................................................................................................... 172 1. FC P ha rdw a re .................................................................................................................................. 19

Table

1. Conventional versus Fluidic Reliability Comparison ..................................................................... 12

4I

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4.fN

1. INTRODUCTION presented, and the inherent advantages of fluidicsare discussed. Finally, the applications of fluidics

The technology known as fluidics provides are highlighted with some specific examples.sensing, computing, and controlling functions withfluid power through the Interaction of fluid (liquid orgas) streams, Consequently, fluidics can perform 2. FLUIDIC COMPONENTSthese functions without mechanical moving parts.The Inherent advantages of fluidics are, therefore, A wide variety of fluidic components is nowsimplicity and reliability, since there are no moving available "off the shelf." As might be expected, theparts to wear out. components of today are vastly improved over their

counterparts of the early 1960's. Figure 2 il-Fluldlcs-origInally called fluid amplifica- lustrates the giant strides made in component

tlion-was discovered in 1959 by a group of scien- packaging by comparing an early 1960's prototypetlists at the U.S. Army Harry Diamond Laboratories unit to a current equivalent off-the-shelf compo-(HDL). During the first 10 years of its existence, nent. Manufacturing techniques have Improved,there was a tendency to try to use fluidics in size has been reduced, and unit cost has beenanything and everything, without giving adequate lowered. In addition, Integrated subsystems haveattention to whether it offered any true advantages replaced breadboard circuits.over existing technologies. This period of trying toover-employ fluidics reached Its peak In the One of the most recent advances in circuit in-mid-1960's. Those days have now passed. Fluidics tegration techniques has been the adoption by HDLIs no longer a novelty; it can stand on Its own of a standard format, designated C format, formerits. fluidic laminates.1 This format permits optimal flex-

ibility within Its 3.3 by 3.3 cm (I.3 by 1.3 in.) area,Since 1970, a number of truly valid applica- and results In a vertical stacking of horizontally

tlions of fluldics have been realized. The areas of laminated elements to build fluidic circuits. Verticaluse include the aerospace Industry, medicine, stacking minimizes Interconnection distances andpersonal-use items, and factory automation, volumes, and thereby minimizes signal losses,Fluidics for military systems has also progressed to parasitic Impedances, and probability of leaks.the point where several systems are in advanced Some typical C format laminate configurations aredevelopment stages. In most cases, the reason for illustrated in figure 3.selecting fluidics has been a combination of low

* cost, high reliability, inherent safety, and the ability Fluidic components are generally classified asto operate in severe environments, sensors, amplifiers, or Interface devices. Sensors

translate a parameter of interest (for example,XAlmost all early (first-generation) fluidic angular rate, distance, or temperature) Into a

devices were operated In the turbulent-flow pressure/flow signal that can then be processed inregime. GInce the mld-1970's, the emphasis at HDL a control circuit. Amplifiers perform the logic andhas shifted to the use of laminar-flow (second- control functions. The Interface devices transformgeneration) fluidic components. Turbulent flow is the signals from the control section of the circuit tocharacterized by a "noisy" jet as Illustrated in an appropriate output (such as electrical display or

7. figure la (p 6); in contrast, laminar flow Is mechanical motion). Each of the categories ofcharacterized by a "quiet" well-defined jet (fig. 1 b). components may be either active or passive. AnTurbulent-flow devices are still used where higher active fluidic component is one that requires apower levels are required. Laminar-flow fluidic separate power source in addition to whatever in-devices are used primarily in signal applications put signals are applied to it. Passive components,where the ability to detect and process extremely on the other hand, operate on the signal powersmall pressure signals is essential. alone. Except for passive circuit components such

In the sections that follow, the basic concepts 1J. W. Joyce, A Catalog of Fluidic C Format Laminates,and components of fluldlu technology are Harry Diamond Laboratorle,; HDL.SR.83-2 (March 1983).

5

Figure 1. Turbulent and laminar jets,

c nas fluid resistors and capacitors, almost all fluidic

- components are active.

2.1 Fluidic Sensors and Interface Devices

Many types of sensors and interfacedevices are available off the shelf. Because of thewide variety of functions offered by these com-ponents, they are not discussed in detail here.

S~~L. M. Sierack12 presents a comprehensive, "albeit somewhat outdated, cataloging of fluidic

2L. M Sieracki, Handbook of Fluidic Sensors, Lorelei Ccip.,contract with Harry Diamond Laboratories, HDL-CR.77.787-1 Figure 2. Fluidic hardware: (a) early prototype and(May 1977). (b) current.

6

ro, 0 00 1 0 0 00 0ANGULAR RATE0000 00000 OF STRUCTURE

0000 Q0 080 0(

0 00

S0 0oooo_ LPA EXHAUST

000000o QOOoOOQ"0 0 0 008 0 0 80 o00 00oo -N ; ..

00oooo 0od-'o0o

Figure 3. Some typical C formet configurations.

sensors-both ott-the-shelf items and those still in /\research and development at the time th~e survey/ '

-* was made. Some of the parameters that can besensed fluidically Include

* angular rate and acceleration,* jerk"- d (angular acceleration)/dt,* position,0 strain,* speed, Figure 4. Silhouette of fluidic LJARS.* concentrationldensity,* sound level,* flow rate, The most often used Interface devices in-* pressure, and clude those that produce mechanical or electrical

*• temperature. outputs, Others yield pressure/flow outputs in a dif--* ferent medium or at a significantly different (usuallyAmong the most commonly used sensors for in- higher) level than that of the control circuit. Ex-dustrial applications is a family of noncontact posl- amples of the latter type of interface device aretion sensors. These devices sense the distance to low-pressure piloted spool or diaphragm valves inan object (analog type) or simply the absence or which the pilot signals are supplied by the fluidic

Spresence of an object (digital type). For military control circuit. The high pressures controlled by, (and civilian) control systems, one of the sensors the spool or diaphragm valve may be used to ac-

with the greatest potential is the laminar jet angular tuate a cylinder or other mechanical device.rate sensor (LJARS). 3 The LJARS can replace ex-

•,pensive mechanical rate gyroscopes in many ap- 2.2 Fluidic Amplifiersplications. A silhouette of a typical LJARS is shownin figure 4. Most fluidlc amplifiers have at least four

•.• .....3T. Ml. Drzewtecki and F. M,. Manton, Fluierlcs 40; The basic functional parts. These include (1) a supply' ~Laminar Jet Angular Rate Sensor, Harry Diamond Laboratories, port, (2) one or more control ports, (3) one or more

HDL.TM-79-7 (December 1979). output ports, and (4) an interaction region. These

7

are illustrated In figure 5, These sections may be 2.2.1 Jet-Deflection Amplifierscompared, respectively, to the cathode, controlgrid, plate, and interelectrode region of a vacuum In jet-deflection (or beam-deflection)tube. Many amplifiers also contain vents to isolate amplifiers, one or more contro! ports are con-the effects of output loading from control flow structed perpendicular to the supply jet (fig. 6). Thecharacteristics. The sound of air escaping from direction of the supply jet is thus altered by flow is-such vents gives many fluidic amplifiers their suing from the control port. This type of controlcharacteristic hiss or whistle. results in proportional or analog performance,

since the jet deflection is continuously varied (over

VENT a limited range) from one output receiver to theother.

SUPPLY

SUPPLY4 INTERACTION OUTPUTMREGION

CONTROL CONTROL

S~~CONTROL -•

CNR VENT VENT

Figure 5. Schematic diagram of basic fluidic amplifierdevice.

The supply jet in the fluidic amplifierpasses into the interaction region where it isdirected toward the output port(s) or receiver(s). OUTPUT OUTPUTControl flow injected into the interaction region AP 0determines the direction and distribution of the"supply flow, which in turn affects the flow reachingthe receiver(s). The amount of pressure or flow SUPPLYrecovery available in a receiver is determined bythe internal shape of the device. Useful ampllfica-tion occurs inasmuch as change in output energies CONTROL"can be achieved with smaller changes in controlenergies.

In general, a fluidic amplifier may becategorized in either of two ways: by the function it VENTperforms or by the fluid phenomenon that is thebasis for its operation, Categorized by function, am-plifiers are either analog (proportional) or digital (bi-stable). Identifying amplifiers by fluid phenomenaproduces the following major categories:

o jet deflection, OUTPUT OUTPUTo wall attachment,

o impact modulation,o flow mode control, and* vortex flow. Figure 8. Jet-deflection fluidic proportional amplifier,

8

. ,= ,2 .X

In all early forms of the analog jet- levels that are more easily and economicallyinteraction amplifier, the flow was turbulent. This transduced. This in turn has increased the numbercondition imposed limitations on the signal-to-noise of fluidic sensors that can now be used successful.levels and dynamic ranges available with such ly. A number of fluidic LPA gain blocks for suchamplifiers. More recent research work at HDL has uses have been documented by Drzewiecki.6

produced the laminar proportional amplifier(LPA). 4 ,5 Typically, an LPA exhibits a pressure gain Not only can the LPA be used as an analogof about 10, a dynamic range of over 1000, and a device, but also LPA's with positive feedback canbandwidth ranging from 100 to 1000 Hz, depending be used to perform most of the common digitalon the supply pressure. The addition of the LPA to logic functions, as Mon 7 has demonstrated. Prelim-the inventory of available fluidic components has inary test results Indicate that power consumptionincreased the potential uses for fluidic systems can be reduced by a factor of 10 or more if LPA'swhere analog control is required. A silhouette of are substituted for equivalent turbulent digital logicthe standard HDL LPA showing the normalized (in elements.terms of the nozzle width, b.) critical parameters isIllustrated in figure 7. 2.2.2 Wall-Attachment Amplifiers

A typical two-dimensional wall-0--0 b attachment amplifier is depicted In figure 8. This

-�f first-generation device has a supply nozzle, controlK50 ports, two walls set back from the supply nozzle,

I SUPPLY

1.15 8.l00 bil CONTROLCOTL

MODEL 3.1.1.8

Figure 7. Silhouette of HDL standard LPA.

Of particular significance has been the OUTPUT OUTPUT

ability of the ILPA to take low-level pressure output Fiue. altocmnfudcbeal mpfersignals from fluidic sensors and amplify them to Fiue8Walttcmn udibltlempfe.

4.M. Manion and G. Mon, Fluerics 33. Design and Staging 6T, M. Orzewiecki, Fluerics 42: Some Commonly Usedof Laminar Proportional Amplifiers, Harry Diamond Laminar Fluidic Gain Blocks, Harry Diamond Laboratories, HDL.Laboratories, HDL-TR- 1608 (September 1972). TM-82- 10 (September 1,982).

ST. M. Drzewieoki, Fluerics 38.: A Computer-Aided Design 7G. Mon, Basic Design Concepts of Laminar Fluid/c DigitalAnalysis for the Static and Dynamic Port Characteristics of Logic Elements Using Laminar Proportional Amplifiers withLaminar Proportional Amplifiers, Harry Diamond Laboratories, Positive Feedback, Trans. ASME. J. Dyn. Sys. Meas. Control,HDL- TR- 1758 (June 1976). 101, 1 (March 1979), 77-80.

*.4, ... . . . . .o o

.¶¶, ~ * ~ ** ** .~ * ,- . -,,..kZ. ._.

and output receivers. The Coanda effect.-a tur. Another configuration of this type ofbulent jet's property of attaching itself to a device is known as the summing impact modulatorwall--causes this device to be bistable. The issu- (SIM). In the SIM, one of the two opposed jets IsIng turbulent jet attaches to one of the walls maintained constant, and the other is varied todownstream of the control ports and subsequently cause the impact plane to shift. The SIM producesflows Into the corresponding output receiver. The an analog output.jet will remain attached to this wall until a sufficientpressure signal is applied to the control port on that 2.2.4 Flow Mode Control Amplifiersside. This signal will inject enough fluid into the low-pressure bubble formed by the attached jet to raise This class of fluidic amplifiers makesthe pressure at that point and switch the jet to the use of the laminar-turbulent flow phenomenon. Inopposite wall. In this manner of operation, digital such devices, the supply jet will be laminar in theperformance is achieved. When one output absence of any control signal, and flow will bereceiver Is "on," the other is "off." Variations In directed toward an output port, as depicted inthe geometrical configurations of this basic device figure 10a. Because the flow is laminar, a signifi-yield elements that can produce most of the com- cant portion of the jet will reach the output receivermon digital logic functions-flip-flop, AND, and produce an output signal. It the jet is disturbed,

2 OR/NOR, and so on. In addition, an oscillator can such as by the injection of transverse control flow* be made by providing a feedback loop from each (fig. 10b), the jet changes from laminar to turbulent* output re-elver to its corresponding control port. flow, and virtually no flow reaches the output

receiver. Thus, when the control signal Is applied,2.2.3 Impact Mcdulation Amplifiers there is no output signal. In essence, this

device-known as as turbulence amplifier-is anWhen two opposed round supply nozzles OR/NOR gate. In addition to pressure/flow, the con-

direct jets along the same axis at one another, an trol signal may be acoustic; this phenomenon is theimpact plane is formed at some point between the basis for a class of fluidic acoustic sensors.two nozzles. This is the basis for the performanceof impact modulator devices. As one jet is weak- (a)ened relative to the other, the Impact plane will SUPPLY OUTPUT

* move toward the weakened jet nozzle. Oneresulting configuration that uses this phenomenon (* . - = .Is the transverse impact modulator shown In figure9. Here, the two opposed jets have an orifice platebetween them. If the Impact plane Is Initially to theright of the orifice plate, It tends to seal oft theorifice, and a positive pressure at the output Is CONTROLrealized. However, as control flow Is injected, thejet on the left is weakened, the impact plane movesto the left side of the orifice plate, and the pressureat the output drops to ambient or slightly below. (b)Thus, a digital logic function Is achieved at theoutput. SUPPLY OUTPUT

* ~~VENT OUTPUT OTUORIFICE PLATE- A MATLN

SUPPLY SUPPLY

CONTROLTRANSVERSEJET CONTROL Figure 10. Flow mode control amplifier: (a) without control

Figure 9. Transverse Impact modulator. signal and (b) with control signal applied.

10

-T ,- *

2.2.5 Vortex Flow Amplifiers 3. ADVANTAGES OF FLUIDICS

In the vortex flow device, flow from the The fact that the basic elements J fluidics, aspower nozzle Is directed .radially inward in a described in section 2, contain no moving mechani.shallow cylindrical chamber, as shown In figure 11. cal parts and require no electricity leads toIn the absence of any control flow, the supply flow numerous inherent advantages of this technologycontinues radially Inward toward the outlet, or for controls applications Among these advantagesdrain, at the center of the chamber, If the control are the following.flow Is Injected tangentially, the supply flow andcontrol flow combine to produce a swirl-type flowpattern which becomes a foced vortex field, rho High reliability: Since there are no movingpressure gradient across the chamber produced by parts to wear out, the normal wear-out types of

pressurefailures are essentially nonexistent. Some specificthis forced vortex field alters the magnitude and the"pattern of the supply flow. Specifically, as control examples of proven high reliability of fluidic sys-flow Is Increased, the supply flow Is decreased, so tems are discussed later in this report.that the device acts as a throttling valve. This sameprinciple Is the basis for the operation of the vortex h lowcs In most uses f ouidcisyseangular rate sensor. Here, no control flow Is In- have a ower Initial cost than competitivetroduced; Instead, the swirl Is Imparted by the equivalents. In addition, the high reliability and low

maintenance of fluidics, combined with low Initial- angular rotation (about the axis of the drain) of the costnre in e tth are it-chamber itself. Differential pressure signals from treme ly l n ot a re d with thatives .an angle-of-attack detector In the drain (or in the tremely low when compared with alternatives.chamber near the drain) correspono to the angularvelocit of th esrEnvironmental Insensitivity: Fluidic com-v o sponents and systems can be designed so that the

(a) "effects of environmental stresses (shock, vibration,SUPPLY aczeleration, temperature, altitude, etc) are"" ~FLOW

minimal. Fluidics also has superior tolerance to theeffects of nuclear or electromagnetic radiation.

. Safety: Fluidic systems require no special-•;j OUTL.. :explosion proofing, since they are Inherently safe,

VORTEX OUTLET This advantage makes fluidic systems particularlyCHAMBER ORIFICE desirable for applications such as munitions

loading or process controllers Involving coirosive(b) SUPPLY CONTROL or explosive chemicals,

FLOW - FLOW

In addition to the four major advantages citedabove, fluidics offers a wide variety of sensingfunctions, some of which are unique. Fluidicsystems are generally small and lightweight com-

OUTLET pared to most other competitive control systems,ORIFICE And the speed of operation, while nowhere near as

fast as electronics, is nevertheless considerablyFigure 11. Vortex flow amplifier: (a) without control flow and faster than mechanical or conventional moving-(b) with control flow, part pneumatic/hydraulic systems.

%11

4. COMMERCIAL APPLICATIONS OF the fluidic controls on the overall thrust-reverserFLUIDICS system is illustrated by the following data. From

maintenance data on the DC-10, the Boeing 747,The applications of fluidics are too numerous and the Lockheed L-1011 thrust reversers, the

to list completely. Consequently, this report only values for mean time between unscheduledaddresses several representative applications, removals (MTBUR) and total component flightboth civilian and military, from different fields, hours are presented in table 1.8 These values show

that the MTBUR for the thrust-reverser system us-In general, fluidics applications have been ing fluidics on the DC-10 Is more than double that of

realized in machine controls, process controls, the other two systems that use conventionalproduction-line controls, air-conditioning controls, pneumatically controlled actuators.aerospace systems, medical equipment, andpersonal-use items. Although only a limited numberof military fluidic systems are "in the field," several Table 1. Co mparson Reiabiitysystems are In advanced development stages and Comparison

offer high promise for eventual field use. Complete Componentthrust.reverser MTBUR total flight

4.1 Aerospace system hours

The first production aerospace fluidic ap- Conventional pneumaticplicatlon In the U.S. was for the thrust-reverser ac- Boeing-747 fan 4035 16,028,680tuator controls for the General Electric CF-6 engine thrust-reverserfor the McDonnell Douglas DC-10 aircraft. Thissystem was placed In revenue service in August Lockheed L.1011 3742 2,252,5891971. (The same control system on the same thrust-reverserengine Is also used on the European A300B Fu/dicAirbus.) The fluidic thrust-reverser hardware Isshown in figure 12. The fluidic system controls the McDonnell Douglasthrust-reverser actuator air motor speed after 90 DC-10 thrust-reverser 9510 6,114,618percent of the actuation stroke and also limits thetorque at the end of the stroke. To achieve thesefunctions, a fluidic operational amplifier, providing Other fluidic commercial applications inlag-lead compensation, accepts the appropriate aerospace Include the thrust-reverser and secon-speed or torque-limiting signal and drives a dary nozzle actuator control systems on the Con-mechanical servovalve that, In turn, actuates the corde SST and pressure ratio and variable Inletsnubbing valve and brake on the air motor as re- guide vane controls for the Rolls-Royce RB211quired to maintain proper control. The actuator and engine on the Lockheed L-101o1 fircraft.

controls must operate in the temperature rangefrom -40 to 177 C (-40 to 350 F). The supply gas 4.2 Industrial Controlfor the fluidic circuitry Is engine-compressor bleed

air at a maximum temperature of 315 C (600 F). Included in this category of fluidic applica-

tions are air-conditioning controls, machine con.Actual performance data for this systemhave demonstrated a mean time to failure (MTTF) trois, process controls, and production-line con-in excess of 600,000 hours. 8 This value is based on trols. Over 100 different applications have beenabout 5,500,000 hours of component operating Identified from these areas of use in the U.S. andtime. An indication of the impact of the reliability of abroad,

8W. T. Fleming and H. R. Gamble, Reliability Data for Fluidic Fluidic controllers for large-scale air-Systems, AiResearch Manufacturing Company of Arizona, con. conditioning systems (for example, in officetract with Harry Diamond Laboratories, HDL-CR-76-092.1 buildings) have been in service since the late(December 1976). 1960's. These units control the flow of air through

12

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fluldlo control module

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I,

9JFgr 2 lii hutrvre oto ytm a nu atcatao o hutrvre n b lii oto oue

-13

the complex ducting circuit of the air-conditioning ment and 12 logic elements to perform the controlsystem. One such controller is shown In figure 13. function. Fluidics was selected for this useThis particular unit uses three summing Impact because it could perform the required operationmodulators to achieve proportional control.9 Inputs more accurately and reliably than competitive ap-to the controller are pressure signals that represent proaches. Other machine-control applications In-parameters such as temperature and relative clude sequencing controls for turret lathes andhumidity. Another type of controller uses a three- sensinglcontrol systems for die protection,stage jet-Interaction fluidic proportional amplifier ina unit that gives positive assurance of fan operation An example of the use of fluidics In proc-In the forced-air system and, at the same time, ess controls Is the application of a fluidic divertereliminates the need for any pneumatic-electric in- valve (fig. 14) to control liquid level. These diverterterface. Over 100,000 fluidic ccntrollers for air- valves are wall-attachment devices with a singleconditioning systems have been sold and installed control port. Flow normally Issues out of one outputby several manufacturers, making this the most leg of the valve; when a control signal is applied,widely used application of a fluidic system. the flow is diverted to the opposite leg, This type of

valve was Installed in a paper and pulp plant In, .~. 1964 to control the level In a white water (paper

stock with a 0.5-percent consistency) chest. 1 Thevalve, which is still In operation, maintains the prop.er level by adding waste condensate water when-ever the chest level Is low. The only maintenancerequired on this valve has been an occasional"cleaning of the control tube to remove pulpdeposits.

" <,

Figure 13, Fluidic air-conditioning controller.

Figure 14. Fluidic diverter valve.

Machine-control applications Include thecontrol of Industrial sewing-machine attachments. Another application of fluidics for processIn one such attachment, a fluidic control system controls is a set-point proportional controller that issenses the leading and trailing edges of a garment used to control the flow of steam in a fiber-texturingmoving through a sewing station.10 The system process.then controls the attachment to cut a continuousthread chain and/or binding flush with the edge of A good example of fluidics In production-the garment. The fluidic circuitry Includes interrupt- line controls Involves the use of the controllerible jet sensors that detect the edges of the gar- shown In figure 15. This controller unit is a fluidic

9J. A. Enright, The impact Modulator Meets the Market, air-gauging cOmparator circuit that detectsFlu/dics Quarterly, 3, 3 (1971). 11R. B. Adams, Some industrial Process Applications of

10ComIng Glass Works, Fluid/c Product Department, Fluid/cs, Fluidic State-of-the-Art Symposium, V(30 September toFlu/dice Case History, Data Sheet FCH-28 (1971). 3 October 1974), 91-117,

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variances from the user's preset quality standards. equipment. Consequently, many respirators haveThe controller can be used with a variety of been designed to operate directly from either ox-available sensors. With these sensor/controller ygen or air supplies that are commonly available incombinations, tolerances as low as 0.0001 In. hospitals. Such respirators thus become natural(0.0025 mm) can be readily and accurately candidates for fluidic controls,monitored. The output of the controller can beeither electric or pneumatic. Many of these in-line 4.4 Personal-Use Itemsfluidic control systems are being used by numerouscompanies in a variety of specific applications. One of the first fluidic personal-use items

to appear on the market was a pulsatingshowerhead (fig. 16). A manually controlled valve,operated by twisting the barrel of the showerheac,provides two modes of operation. One mode Is acontinuous steady stream, as in any conventionalshowerhead. In the other mode, a fluidic oscillatorproduces a pulsating flow out of each of two rec-tangular slots In the face of the showerhead. Thispulsating flow produces a massaging action.

Figure 15. Fludicc controller.

4.3 Medicine

Investigating the feasibility of usingfluidics in life-support medical equipment was oneof the first research and development effortsundertaken at HDL in the early 1960's. Because of Figure 16. Fluidic pulsating ehowerhead.the high reliability of fluidics, the technology wasconsidered a strong contender for items such as Other personal-use fluidic products In-pulsatile extracorporeal blood pumps and respira- clude a family of fluidic lawn sprinklers and oral ir-tors, both of which Involve controlling the move- rigators. In the former, the back and forth action ofment of fluids. Today, several medical devices on the sprinkler to sweep an area of the lawn Isthe market Incorporate some degree of fluidic achieved without mechanical moving parts. Thecontrol. oral irrigator is similar to the showerhead in that it

provides a pulsating flow to massage the gums andThe leading candidate for fluidic controls enhance the rinsing action.

to date has been respirators, In which fluidic con-trols have been used In several different types. The Most recently, fluidic windshield washerschief advantages of fluidics In respirators are in- first app,:~rd as standard equipment on two 1979creased reliability over conventional pneumatic automobile models. Today, the vast majority of newcontrols and Inherent safety. Respirators are, of cars mnade In this country are equipped with fluidiccourse, normally used in areas where high oxygen windr,hield washers. A single fluidic oscillator (orlevels require explosion-proofing of any electrical two oscillators on some larger cars) replaces the

15

conventional two-nozzle configuration. With the turn of the aircraft In a particular axis. The fluidicfluidic washer, the wiper blades are no longer signal from the rate sensor Is amplified by severalresponsible for distributing water because the jet-interaction fluidic porportional amplifiers,oscillator output sprays the entire windshield sur- shaped dynamically by passive fluidic RC-networksface In a fan-like pattern. In addition, the oscillator and then converted Into mechanical motion bynozzle produces droplets that are larger than those means of conventional hydraulic servoactuators,from the conventional system and are consequent- The SAS uses the on-board hydraulic power supplyly less affected by wind. to operate the fluidic circuitry. This system is low-

cost, easy to maintain, and more reliable than elec.trohydraulic or electromechanical equivalents.

5. MILITARY APPLICATIONS OF FLUIDICS

Maintenance and logistics costs are extremelyhigh In a military system's life cycle, and almost allsuch systems must operate through environmentalextremes; hence, a military system has to be rug-ged. As a result, the military is interested in fluidlcsbecause of its reliability and environmental Insen-sitivity. Low initial cost, another military concern,can be realized by the use of fluidic systems.

The fluidic generator (fig. 17), an Interfacedevice that converts pneumatic energy into elec-trical energy, has been type classified in a Navysystem. In this application, the fluidic generator in-gests ram air and converts It to electrical energy to Figure 17. Fluidic generator.supply the total electrical power requirements of abomblet dispenser system. The aircraft must be fly-ing above a specified velocity In order for thegenerator to operate; therefore, no electrical powerIs available below the specified velocity. Hence,fluidics Is used as an environmental safety systemby allowing the pilot to activate the dispenser only ifthe aircraft is flying at or above the specified veloci-ty range. The Army recognized the potential of us-ing the fluidic generator as an Inexpensive meansof furnishing the total power requirements of anelectronic fuze. In addition, safety Is enhanced,since no power Is generated unless the projectile isin flight. These advantages have led to the selec-tion of the fluidic generator for the Army's MultipleLaunch Rocket System.

Within the military, the Army and Navy have Figure 18. Fluldic single.axis stability augmentationcosponsored a development program for a fluidic system.stability augmentation system (SAS) for helicop-ters. The SAS assists the pilot by providing rota- A series of flight tests for the fluidic SAS on thetional damping about one or more axes. A single- Army's OH-58 helicopter (using a two-axis SAS)axis fluidic SAS is shown in figure 18. The SAS uses and the Navy's TH-57 helicopter (using a single-a vortex angular rate sensor that senses the rate of axis SAS) produced over 12,000 hours of total air-

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craft flight time.1 2 From these tests, the measured The first development program based onmean time between failures (MTBF) for the fluidic second-generation fluidics Involved stabilizing theSAS was 4,557 flight hours. Since the failures ex- gun tube on a tank. The resulting two-axis stabiliza.perienced during these tests of prototype SAS's tion system used the LJARS together with LPA gainare considered to be about 90-percent correctable, blocks as the heart of the sensing and controllingthe estimated MTBF for final production units Is circuitry, 13 This system was successfully demon-"about 25,000 to 50,000 flight hours, Investigations strated on an M48A5 tank In April 1979. Overall per-

* have shown that the electromechanlcal flight. formance of the fluidic system equalled or exceed.control equipment on the Army's Huey Cobra ed that of the electrohydraulic system currently inhelicopter has exhibited MTBF of about 140 flight use on the tank.hours. By comparison, the fluidic SAS prototypeMTBF is more than 30 times greater than that of From the results of the gun stabilization pro-the Huey Cobra system, which is considered to be g ra m the res ens ou are now bein ga mature one. These data, together with those from gram, fluidic rate sensing circuits are now beingthe DC-10, clearly demonstrate that fluidic systems developed for roll rate control of cannonmlaunchedare extremely reliable. guided projectiles and missiles. The complete ratesensing circuit consists of (1) an electrically driven

pump to supply air to the fluidic circuit, (2) anAnother fluidic application that has demon- LJARS with several (usually two or three) stages of

strated high reliability is the pressure-regulating LPA's, (3) a transducer to convert the fluidic outputsystem for the Navy's S-3A aircraft. The system, pressure signal to an electrical signal, and (4) anshown In figure 19, controls the coolant air for the electronic control unit to accept the transduceraircraft avionics. A similar regulating system is also signal and to process and scale It as required byused on the Navy's F-18 airpiane. the overall control system that is fed by this rate-

sensing circuit. Figure 20 shows typical hardwarefor this rate-sensing application.

Figure 19. Fluidic pressure-regulating system. Figure 20. Fluidic rate-sensing hardware.

12 L. J. Banaszak and W. J. Posingles, Hydrofluidic Stability 13 C. L. Abbott et al, A Study of Fluidic Uun StabilizationAugmentation System (HYSAS) Operational Suitability Systems for Combat Vehicles: Final Report, A/ResearchDemonstration, Applied Technology Laboratory, USAAMRDL- Manufacturing Co. of Arizona, contract with Harry DiamoncTR-77-31 (October 1977), Laboratories, HDL-CR-80-100-1 (April 1980).

17

Another fluidic device that uses second- military use, It has potentially even greater use Ingeneration fiuldics Is the fluidic capillary pyrometer the civilian sector for controlling high-temperature(FCP).14 The principle of operation for the FOP is processes, which will result In significant energyanalogous to the operation of an electronic savings and Improvement of the quality of theresistance thermometer. In this system, the sens. product.Ing probe contains a temperature-sensitive resistorIn the form of a capillary tube, A small flow of air (or Several servovalve manufacturers are now of-any gas) Is maintained through the tube. The fluid fering a more reliable product by using fluidics Inresistance of the capillary Is directly proportional to the first stage of two-stage valves. Two new, high-fluid viscosity, which, In turn, Is a function of performance aircraft-the Air Force F-16 and thetemperature. Therefore, If heat Is applied to the Navy F-18-are using these fluldically controlledcapillary, its resistance will change, yielding a servovalves In several of their subsystems.pressure output as a function of temperature.Typically, this pressure change Is quite small, mak-Ing conventional transduction Impractical. Conse- 6 CONCLUSIONSquently, the pressure changes are amplified usingan LPA gain block; the amplified signal can now beread on a pressure gauge, transduced to an elec- The technology known as fluidics is quietly ad-tronic readout, or interfaced into a control system, vancing Into commercial and military use. The ad.The probes can be made from any material that vantage of this techonology's high reliability hasTheprobscan survivebthe e maden irany w h tepa- been conclusively demonstrated from data on thecan survive the environm ent In w hich the tem pera- i -rv n s te on he D 10 a d he y r ul c -ture measurements are to be made. Successful airdriven system on the DC-oe and the hydraulical-tests of the FCP have been made In blast furnace ly driven system on helicopters. The advent of thecupolas (>1650 C), forging furnaces (>1425 C) laminar proportional amplifier has resulted inNaval boiler flames (>1650 C), molten Iron (>1540 fluidic systems with more precision control-C), and induction furnaces (2300 C). Figure 21 resulting in an Increase of potential use of thisQ, ad Iducton urnaes >230 Q.Figue 2 technology.shows typical FCP hardware, consisting of a probeand a control box that contains the fluidic circuitand readout. Although the FOP was developed for Fluidics has now been accepted as a viable

technology for military applications and for com-14R. M. PhIlippi and T. Negas, A Preliminary Industrial/F/ed mercial use. It is expected that the coming yearsEvaluation of the Fluid/c Capillary Pyrometer, ASME Publication will f me Idesprcad usao thi avningG0077,20h An/ersn/f Fu/e/c Sypoium(Nvemerwill find more widespread use of this advancingG00 177, 20th Anniversary of Fluidics Symposium (Novembertehogy1980). technology.

18

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FIgure 21. FCP hardware.

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Literature Cited

1. J. W. Joyce, A Catalog of Fluidic C Format 8. W. T. Fleming and H. R. Gamble, ReliabilityLaminates, Harry Diamond Laboratories, HDL. Data for Fluidic Systems, AiResearch Manufactur-SR-83-2 (March 1983). Ing Company of Arizona, contract with Harry Dla-

mond Laboratories, HDL-CR-76-092-1 (December2. L, M. Sleracki, Handbook of Fluidic Sensors, 1976).

Lorelei Corp., contract with Harry DiamondLaboratories, HDL-CR-77-787-1 (May 1977). 9. J. A. Enright, The impact Modulator Meets the

Market, Fluidics Quarterly, 3, 3 (1971).3. T. M. Drzewiecki and F. M. Manion, Fluerics

40: The Laminar Jet Angular Rate Sensor, Harry 10. Corning Glass Works, Fluidic Product Depart-Diamond Laboratories, HDL-TM-79-7 (December ment, Fluid/cs Case History, Data Sheet FCH-2B1979). (1971).

4. F. M. Manion and G. Mon, Fluerics 33: Design 11. R. B. Adams, Some Industrial Process Ap-and Staging of Laminar Proportional Amplifiers, plications of Fluid/cs, Fluidic State-of-the-Art Sym-Harry Diamond Laboratories, HDL-TR-1608 (Sep- poslum, V (30 September to 3 October 1974),tember 1972). 91-117.

5. T. M. Drzewlecki, Fluerics 38: A Computer- 12. L. J. Banaszak and W. J. Posingles, Hydroflu-Aided Design Analysis for the Static and Dynamic idic Stability Augmentation System (H YSAS) Opera-"Port Characteristics of Laminar Proportional tional Suitability Demonstration, Applied Technol-Amplifiers, Harry Diamond Laboratories, HDL- ogy Laboratory, USAAMRDL-TR-77-31 (OctoberTR-1758 (June 1976). 1977).

6. T. M. Drzewleckl, Fluerics 42: Some Com- 13. C. L. Abbott et al, A Study of Fluidic Gunmonly Used Laminar Fluidic Gain Blocks, Harry Stabilization Systems for Combat Vehicles: FinalDiamond Laboratories, HDL-TM-82-10 (September Report, AiResearch Manufacturing Co. of Arizona,1982). contract with Harry Diamond Laboratories, HDL-

CR.80.100-1 (April 1980).7. G. Mon, Basic Design Concepts of Laminar

Fluidic Digital Logic Elements Using Laminar Pro- 14. R. M. Phillippi and T. Negas, A Preliminary in-portional Amplifiers with Positive Feedback, Trans. dustrial Field Evaluation of the Fluidic CapillaryASME, J. Dyn. Syst. Meas. Contro, 101, 1 (March Pyrometer, ASME Publication G00177, 20th An-"1979), 77-80. niversary of Fluidics Symposium (November 1980).

20

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Bibliography

Technical Reports Katz, S., and E. Hastle. Fluerics 31: The Transitionfrom Isothermal to Adiabatic Capacitance in Cylin-

Carter, V., and D. Marsh. Fluerlcs 23: A dr/ca/ Enclosures. Harry Diamond Laboratories,Bibliography. Supplement 1. Harry Diamond HDL-TM-71-35 (December 1971).Laboratories, HDL-TR-1597 (April 1972).

Keto, J. R. Fluerics 29: Transient Response ofCycon, M. F., and D. J. Schaffer. Design Guide for Some Flueric Components to Step Waves and Ap-Laminar Flow Fluidic Amplifiers and Sensors. Gar- pl/cation to Matching. Harry Diamond Laborato-rett Pneumatic Systems Division, contract with ries, HDL-TR-1531 (September 1970).Harry Diamond Laboratories, HDL-CR-82-288-1(April 1982). Kirshner, J. M. Fluerics 1: Basic Principles. Harry

Diamond Laboratories, HDL-TR-1418 (NovemberDeadwyler, R. Fluerics 26, Theory of Temperature 1968).and Pressure-Insensitive Fluid Oscillators. HarryDiamond Laboratories, HDL-TR-1422 (March Klrshner, J. M. Fluerics 35: Jet Dynamics and Its1969). Application to the Beam Deflection Amplifier. Harry

Diamond Laboratories, HDL-TR-1630 (July 1973).Drzewleckl, T, M. Fluerics 39: The Fluid Mechanicsof Fluid/cs. Harry Diamond Laboratories, HDL- Kirshner, J. M., and R. N. Gottron. Fluerics 28:TR-1798 (February 1977). State of the Art 1969. Harry Diamond Laboratories,

HDL-TR-1478 (December 1969).Drzewlecki, T. M. Fluerics 37: A General PlanarNozzle Discharge Coefficient Representation. Manion, F. M., and G. Mon. Fluerics 33: Design andHarry Diamond Laboratories, HDL-TM-74-5 (August Staging of Laminar Proportional Amplifiers. Harry1974). Diamond Laboratories, HDL-TR-1608 (September

Drzewleckl, T. M. Fluerics 34: Planar-Nozzle 1972).

Discharge Coefficients. Harry Diamond Laborato- Phillippi, R. M., et al. Design of a Fluidic Capillaryries, HDL-TM-72-33 (September 1973). Pyrometer for Contact Duty at Temperatures to

2750 C. 6th Symposium on Temperature, ItsFluidics State-of-the-Art Symposium, Proceedings. Measurements and Control (March 1982).Harry Diamond Laboratories (30 September to 3October 1974). Phillippi, R. M., and T. M. Drzewleckl. Fluerics 41:

Single-Sided Control Port Characteristics ofGaylord, W., and V. Carter. Fluerics 27: Flueric Laminar Proportional Amplifiers for Arbitrary InputTemperature-Sensing Oscillator Design. Harry Dla- Loading. Harry Diamond Laboratories, HDL-mond Laboratories, HDL-TR-1428 (April 1969). TR-1901 (February 1980).

Goto, J., and T. M. Drzewieckl. Fluerics 32: An Roffman, G. L., and S. Katz. Fluerics 15: Ex-Analytical Model for the Response of Flueric Wall- perimental Fluidic Analog Computation. Harry Dia-Attachment Amplifiers. Harry Diamond Laborato- mond Laboratories, HDL-TR-1292 (June 1965).ries, HDL-TR-1598 (June 1972).

Roundy, J. S. Manufacturing Techniques for Pro-Gottron, A. N., and S. D. Weinger. Fluerics 14: ducing High Quality Fluidic Laminates at Low Cost.Parameters Affecting the Noise in No-Moving-Parts Garret Pneumatic Systems Division, contract withFluid Devices. Harry Diamond Laboratories, HDL- Naval Air Systems Command, N00019-78-C-0365TR-1283 (April 1965). ' (September 1980).

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%

Spyropoulos, C. E. Fluerics 36: Large-Scale Model- Military StandardsIng of Laminar Flueric Devices. Harry DiamondLaboratories, HDL-TM-73-28 (February 1974). MIL-STD-1306A. Fluerics: Terminology and Sym-

bols. 8 December 1972.Toda, K., et al. Fluerics 30: The Matched Acoustic

Generator. Harry Diamond Laboratories, HDL- MIL-STD-1361A. Fluidics: Test Methods and In-TR-1574 (December 1971). strumentation. 28 September 1973.

4,

22

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