US3738391A

US3738391A - Fluid pressure comparator

Info

Publication number: US3738391A
Application number: US00085685A
Authority: US
Inventors: R Adams
Original assignee: Moore Products Co
Current assignee: Moore Products Co
Priority date: 1970-10-30
Filing date: 1970-10-30
Publication date: 1973-06-12
Anticipated expiration: 1990-06-12

Abstract

A fluid pressure comparator is provided which imposes a minimal loading of either of the pressure signals and which at the same time provides a high degree of resolution in its output for relatively small pressure changes in the signal input. The comparator includes a chamber with a fluid inlet having a pair of delivery passageways for the fluids whose pressures are to be compared and a fluid outlet providing a resistance to flow greater than that of either of the delivery passageways. The passageways may be inclined with respect to the longitudinal axis of the chamber or opposed. The fluid exiting from fluid outlet may provide a directional signal and this signal may be utilized with a proportional diverting valve to provide a high capacity output signal. The space beyond the fluid outlet may be of such a nature that loss of sensitivity on account of dirt build up is avoided.

Description

United States Patent 1 Adams FLUID PRESSURE COMPARATOR [75] Inventor: Robert B. Adams, Tredyffrein Township, Chester County, Pa.

[73] Assignee: Moore Products Co., Spring House,

[22] Filed: Oct. 30, 1970 [21] Appl. No.: 85,685

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 828,638, May 28,

1969, abandoned.

[52] U.S. Cl. 137/823 [51] Int. Cl. F15c 1/14 [58] Field of Search 137/815 [56] References Cited UNITED STATES PATENTS 3,209,774 10/1965 Manion 137/815 3,216,439 11/1965 Manion.... 137/815 3,233,621 2/1966 Manion.... 137/815 3,411,520 11/1968 Bowles 137/815 3,457,934 7/1969 Kinner 137/815 3,267,946 8/1966 Adams et al.... 137/815 3,238,959 3/1966 Bowles 137/815 3,177,888 4/1965 Moore 137/815 11 3,738,391 [451 June 12,1973

Primary Examiner-Samuel Scott Attorney-Zachary T. Wobensmith, II

[57] ABSTRACT A fluid pressure comparator is provided which imposes a minimal loading of either of the pressure signals and which at the same time provides a high degree of resolution in its output for relatively small pressure changes in the signal input. The comparator includes a chamber with a fluid inlet having a pair of delivery passageways for the fluids whose pressures are to be compared and a fluid outlet providing a resistance to flow greater than that of either of the delivery passageways. The passageways may be inclined with respect to the longitudinal axis of the chamber or opposed. The fluid exiting from fluid outlet may provide a directional signal and this .signal may be utilized with a proportional diverting valve to provide a high capacity output signal. The space beyond the fluid outlet may be of such a nature that loss of sensitivity on account of dirt build up is avoided.

11 Claims, 8 Drawing Figures PATENTEU Jul 1 2 3am Q? 3 A TTORNE Y FLUID PRESSURE COMPARATOR CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation in part of my prior application filed May 28, 1969, Ser. No. 828,683, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fluid pressure comparators and more particularly to such comparators having no moving parts.

2. Description of the Prior Art It has heretofore been proposed to provide pressure comparators or differential pressure amplifiers for comparing the pressures between two fluid streams, for example Bowles, U. S. Pat. Nos. 3,272,212 and 3,238,959; Sieracki, U. S. Pat. No. 3,452,768 and Manion, US. Pat. No. 3,209,774. In all of these devices the major pressure drop occurs upstream of the region where the two streams interact with each other. As a result, all of these devices have a low degree of sensitivity and low impedance at the balance point.

Another structure which might be used for comparing fluid pressure is shown in Adams U. S. Pat. No. 3,187,763. It has been found that although this structure has good sensitivity to flow changes in the two streams to be compared that it exhibits very low sensitivity to pressure changes in these two streams.

Other structures have been proposed but these also have limitations.

Most of the fluid amplifiers and fluid pressure comparators heretofore available have been subject to loss of sensitivity because of dirt build up on the walls, beyond the fluid interaction chamber from contaminating particles in the supply fluid. This is particularly true where the fluid is air which has been compressed in a mechanical air compressor, the contaminating particles including oil particles and particularly burned oil particles, and water vapor.

SUMMARY OF THE INVENTION In accordance with the invention a device is provided for comparing two fluid pressures which imposes a minimal loading of either of the pressure signals and at the same time provides a high degree of resolution in its output for relatively small signal.

In accordance with the invention, also, a fluid pressure comparator is provided which is simple in construction, effective in its operation and is essentially free from maintenance problems.

In accordance with the invention, also, a fluid pressure comparator is provided with relatively high input impedance and high resolution in the active range at and near the balance point.

In accordance with the invention, also, a device is provided for comparing two fluid pressures which imposes a minimal loading of either of the pressure signals, at the same time provides a high degree of resolution in its output for relatively small changes in the input signal pressure and avoids loss of sensitivity due to interior dirt build up.

In accordance with the invention, also, a fluid pressure comparator is provided which is simple in construction, effective in its operation and is essentially pressure changes in the input free from maintenance problems, particularly those attendant upon the use of compressed air from mechanical air compressors.

Other objects and advantageous features of the invention will be apparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part thereof, in which:

FIG. 1 is a plan view, enlarged, of a perferred form of comparator in accordance with the invention, parts being broken away to show the details of construction;

FIG. 2 is a sectional view taken approximately on the line 22 of FIG. 1;

FIG. 3, is a plan view, enlarged, of a preferred form of comparator in accordance with the invention, parts being broken away to show the details of construction;

FIG. 4 is a sectional view taken approximately on the line 4-4 of FIG. 3;

FIG. 5 is a view similar to FIG. 1 showing another preferred form of comparator in accordance with the invention;

FIG. 6 is a sectional view taken approximately on the line 66 of FIG. 5;

FIG. 7 is a plan view of a fluidic relay employing the comparator of the present invention; and

FIG. 8 is a sectional view taken approximately on the line 8-8 of FIG. 7.

It should, of course, be understood that the description and drawings herein are illustrative merely, and that various modifications and changes can be made in the structure disclosed without departing from the spirit of the invention.

Like numerals refer to like parts throughout the several views.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to FIGS. 1 and 2 of the drawings, the comparator 10 there shown includes a top cover plate 11, an intermediate plate 12 which serves as a body portion, and a bottom cover plate 13, the plates l1, l2 and 13 being secured together in any desired manner, such as by screws 14.

The body portion 12 has a transverse passageway therein consisting of aligned and meeting passageways l7 and 18. The passageway 17 has a fluid inlet connection 19 for the application in the passageway 17 of one of the fluid pressures to be compared.

The passageway 18 has a fluid inlet connection 20 for the application in the passageway 18 of the other of the fluid pressures to be compared.

The

passageways

17 and 18 communicate through a fluid inlet opening 21 with a fluid interaction chamber 22 in the body portion 12 whose longitudinal axis is perpendicular to the axis of passageways l7 and 18. The chamber 22 has opposite diverging

side walls

23 and 24 which extend from the inlet opening 21 to

transverse end walls

25 and 26 which termite at an outlet opening 27. The outlet opening 27 is longitudinally axially aligned with the inlet opening 21. The outlet opening 27 is preferably smaller in area than the inlet opening 21 and the passageways l7 and 18 so as to interpose a greater resistance to flow than that provided by the opening 21, or either of the

passageways

17 and 18.

The body portion 12, beyond the outlet opening 27 has diverging wall portions 28 and 29 which terminate at transversely extending

end walls

30 and 31 with an open space 33 therebeyond.

In use, fluid pressures to be compared are applied through the

fluid inlets

19 and 20, are effective in the

passageways

17 and 18, and the resultant is effective as a flow through the inlet opening 21 into the chamber 22.

The initial portion of the flow path in chamber 22 is determined by the momentum interaction between the jets issuing from

fluid passageways

17 and 18. The tangent of the angle between the longitudinal axis and the initial flow path is proportional to the ratio of the difference in pressures supplying the passageways l7 and 18, and the total momentum of the flow as it enters chamber 22. There is a significant advantage obtained by designing the device so that under all operating conditions (i.e. all pressure levels) the momentum of the flow is ltept very small at this point in that this makes the jet angle large. The momentum of this flow is kept small at all operating conditions by sizing the discharge passageway 27 smaller than either of the

passageways

17 and 18, and inlet 21.

The initial angle of the path of flow in chamber 22, established by momentum interaction, is further increased by the attraction of one or the other of chamber sidewalls 23 or 24.

The diverging and converging

wall portions

23, 25 and 24, 26 further magnify and reverse the angle of the stream as it approaches the outlet opening 27. The angle of the stream is decreased by the action of the pressure drop through the exit 27 but experience has shown that the final angle of the emergent stream is of the same order of magnitude as the angle established in the chamber 22 by momentum interaction and side wall attraction and, for small pressure differences, the

angle is far greater than if the total pressure drop had occurred at the junction of the streams at the opening 21 as in Bowles, U. S. Pat. Nos. 3,238,959, and 3,272,212; Sieracki, U. S. Pat. No.'3,452,768 and Manion U. S. Pat. No. 3,209,774.

If the pressure difference between the passageways l7 and 18 is great, some of the fluid from the higher pressure location may flow into the lower pressure location so that it is the algebraic sum of the flows in the

passageways

17 and 18 which exits through the-openings 2 1 and 27.

It has been observed that the structure, in accordance with the present invention, presents an impedance to input pressures to be compared which is much higher when these two pressures are near each other than when they are at substantially different values. Furthermore, the highest value of this impedance is substantially higher than can be accounted for by computatiori from the simple cross sections of the passageways presented to these fluid streams. This phenomenon has not been observed in any of the prior art, including Adams, U. S. Pat. No. 3,187,763; Bowles, U. S.

Pat. Nos. 3,238,959 and 3,272,212 and Manion U. S.

11a, 12a and 13a being secured together in any desired manner such as by screws 14.

The body portion has a transverse passageway therein consisting of aligned and meeting

passageways

17 and 18. The passageway 17 has a fluid inlet connection 19 for the application in the passageway 17 of one of the fluid pressures to be compared.

The

passageways

17 and 18 communicate through a fluid inlet opening 21, preferably having sharp inlet corners, with a fluid interaction chamber 22 in the body portion 12 whose longitudinal axis is perpendicular to the axis of passageways l7 and 18. The chamber 22 has opposite diverging

side walls

23 and 24 which extend from the inlet opening 21 to aligned

transverse end walls

25 and 26 which terminate at an outlet opening 27. The outlet opening 27 is longitudinally axially aligned with the inlet opening 21. The outlet opening 27 preferably has sharp inlet corners, short

parallel walls

34 and 35, is preferably smaller in area than the inlet opening 21 and the

passageways

17 and 18 so as to interpose a greater resistance to flow than that provided by the opening 21, or either of the passageways l7 and 18.

The top cover plate 11a, body portion 120 and bottom cover plate 13a, commencing at outlet opening 27, have diverging

side wall portions

28a and 29a with an included angle of the order of 120 and which extend to opposite aligned transverse walls 30a and 31a and from which opposite

parallel side walls

36 and 37 extend.

The top cover plate 11a provides a top wall for the chamber 22. Commencing at the

walls

25 and 26 and downstream thereof it is offset upwardly a distance at least as great as the height of the chamber 22; v

The bottom cover plate 13a provides a wall for the chamber 22. Commencing at the

walls

25 and 26 and downstream thereof it is offset downwardly a distance at least as great as the height of the chamber 22.

A delivery space 48 is thus provided beyond the outlet opening 27.

A fluid divider 50 can be provided between thetop and bottom wall plates 11a and 13a and at the discharge end of the space 48 to separate

delivery passageways

51 and 52. I

The rear terminus 53 of the plates lland 13a and divider 50 can be curved for the reception of a turbine wheel 55 rotatable by direction of impact of fluid from the

passageways

51 and 52. i

In use, fluid pressures to be compared are applied through the

fluid inlets

19 and 20, are effective in the aligned and meeting passageways l7 and 18, and the resultant is effective as a flow through the inlet opening 21 into the chamber 22.

The initial portionof the flow path in chamber 22 is determined by the momentum interaction between the jets issuing from

fluid passageways

17 and 18. The tangent of the angle between the longitudinal axis and the initial flow path is proportional to the ratio of the difference in pressures supplying the passageways l7 and 18, and the total momentum of the flow as it enters chamber 22. There is a significant advantage obtained by designing the device so that under all operating conditons (i.e. all pressure levels) the momentum of the flow is kept very small at this point in that this makes the jet angle large. The momentum of this flow is kept small at all operating conditions by sizing the discharge passageway 27 smaller than either of the passageways l7 and 18, and inlet 21.

The diverging

wall portions

23 and 24 and

transverse wall portions

25 and 26 further magnify and reverse the angle of the stream as it approaches the outlet opening 27. The angle of the stream is decreased by the action of the pressure drop through the exit 27 but experience has shown that the final angle of the emergent stream is of the same order of magnitude as the angle established in the chamber 22 by momentum interaction and side wall attraction and, for small pressure differences, the angle is far greater than if the total pressure drop had occurred at the junction of the streams at the opening 21.

if the pressure difference between the passageways l7 and 18 is great, some of the fluid from the higher pressure location may flow into the lower pressure location so that it is the algebraic sum of the flows in the passageways l7 and 18 which exit through the

opening

21 and 27.

The size and disposition of the delivery space 48 attendant upon the spacing of the contiguous wall portions 11a and 13a prevents dirt which may tend to adhere to and accumulate upon any bounding portion of the space 48 from adversely affecting the sensitivity.

The signals available at the space 48 may be utilized in any desired manner and for this purpose the reversible turbine wheel 55 may be utilized, the number of rotations of the shaft being recorded in a well known manner.

Referring now to FIGS. 5 and 6 the comparator 110 there shown has top and bottom cover plates 111 and 113 with an intermediate plate or body portion 112 therebetween, with the plates being held together such as by clamping screws 114.

Passageways

117 and 118 are provided in converging relation, intersecting at the inlet opening 121 of an in teraction chamber 122. The passageways 1.17 and 118 have

fluid inlet connections

119 and 120 for delivery thereto of the fluid pressures to be compared.

The interaction chamber 122 has opposite diverging

side walls

123 and 124 and converging side walls 125 and 126 with an outlet opening 127. The outlet opening 127 is axially aligned with the inlet opening 121 and is preferably smaller in area than the inlet opening 121 and either of the

passageways

117 and 118.

Beyond the outlet opening 127, diverging

walls

128 and 129 are provided, interrupted by'vents 134 which prevent fluid locking onto the

walls

128 and 129. The elimination of the vents 134 will provide bistable output action.

A turbine wheel 135 is provided, carried on a shaft 136 journaled in bearings 137, and is .rotatable in a direction determined by the direction of impact of fluid from the outlet opening 127.

The mode of operation is similar to that previously described, the direction of the fluid jet in the chamber 122 being at an angle determined by the momentum interaction and side wall attraction. The relatively small outlet opening 127 provides a large pressuredrop at this location compared to that at the

inlet passageways

117 and 118 with enhanced amplification.

If the ratio of the length of the

chamber

22 or 122 to the inlet opening 21 or 121 is increased the action can be made bistable. Bistable action can also be effected by decreasing the angle of divergence between the walls 28 and 29.

Referring now to FIGS. 7 and 8, the application of the comparator to a fluidic relay is there illustrated.

As shown in FIGS. 7 and 8, a comparator 210 is provided similar to those previously described having a top cover plate 211, a central body portion 212 and a bottom cover plate 213, held together in any desired manner.

The comparator 210 has a fluid pressure inlet connection 219 for a low capacity input signal. The fluid connection 219 is connected to a fluid passageway 217 which is in opposed relation to a fluid passageway 218.

The

passageways

217 and 218 are connected through an inlet opening 221 to a fluid interaction chamber 222 having an outlet opening 227. A divider 40 is provided aligned with the longitudinal axis of the chamber 222 to direct fluid into either of the

control fluid passageways

41 and 42. Outwardly of the

passageways

41 and 42

vent passageways

43 and 44 are provided communicating with the atmosphere.

A fluidic amplifier 45 of any desired type is provided having a supply of fluid under pressure connected to a nozzle 46 for directing a jet of fuid. The nozzle 46 has the fluid control passageways 4 1 and 42 connected to opposite sides thereof for controlling the direction of fluid flow.

Beyond the nozzle 46, a divider separates a delivery passageway 56 for pressure utilization from a vent passageway 57. An additional vent passageway 47 is also provided at the outer side of the passageway 56.

The passageway 56 has a feedback fluid connection 58 connected thereto and to the passageway 218. The feedback connection 58 provides a negative feedback for enhanced linearity between the output and input relation.

If the negative feedback is one hundred percent the gain is reduced to one, with the output equal to the input but with enhanced precision and enhanced flow capacity.

Theadvantages in employing an amplifier with one hundred percent negative feedback is that the amplifier is capable of supplying much more energy in terms of flow than could be supplied by the input signal. Such an amplifier presents a very high input resistance and thereby does not impose any load on the input signal which might cause the signal to depart from its no-load value.

Accordingly with a high gain amplifier such as that of FIGS. 7 and 8 or any other suitable high gain amplifier with megative feedback to one of the two input connections of a comparator, such as those of FIGS. 1 to 6, inclusive, and a pressure signal applied to the other of the input connections, the output of the system will closely follow the applied input and be capable of supplying high flow without causing any droop of the input signal.

By introducing'slight asymmetry or bias either in the comparator or in the amplifier the negative feedback can bemade to supply all' the flow required'by the comparator so that the amplifying section will offer infinite resistance to the applied signal.

It will thus be seen that a comparator has been provided for attaining the objects of the invention.

1 claim: l. A fluid interaction device for comparing fiuid pressures which comprises I a chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying fluid pressures to be compared, fluid inlet means at the inlet end of said chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber, said chamber having a single outlet opening at said outlet end thereof discharging the algebraic sum of the flow in said connections, and means for amplifying the output from said outlet opening, said amplifying means including a fluid outlet, one of said fluid inlets being connected to said fluid outlet of said fluid amplifier in phased relation for negative feedback whereby the pressure supplied to said fluid outlet will follow closely the pressure applied to the other of said fluid inlets. 2. A fluid interaction device as defined in claim 1 in which said amplifying means includes a fluidic device. 3. A fluid interaction device as defined in claim 1 in which 7 means is provided for biasing the negative feedback action to supply to one of said fluid inlets all the fluid required for delivery through said outlet opening. 4. A fluid interaction device for comparing fluid pressures which comprises a chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying fluid pressures to be compared and the total fluid flow to said chamber, and fluid inlet means at the inlet end of said chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber, said chamber having a single flow passageway at said outlet end thereof through which said total flow passes and said passageway having a flow resistance greater than that of either of said fluid supply connections for limiting the pressure drop in said supply connections. 5. A fluid interaction device as defined in claim 4 in which said fluid passageways are in opposed and aligned relation to each other. 6. A fluid interaction device for comparing fluid pressures which comprises a chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying fluid pressures to be compared and the total fluid flow to said chamber, and fluid inlet means at the inlet end of said chamber communicating with both said fluid connectionsand including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber,

said chamber having a single flow passageway at said outlet end thereof through which said total flow passes, said passageway having an effective cross sectional area smaller than the effective cross sectional area of either of said fluid connections for limiting the pressure drop in said supply connections.

7. A fluid interaction device for comparing fluid pressures which comprises an interaction chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween,

a first and second fluid connection supplying fluid pressures to be compared and the total fluid flow to said interaction chamber,

fluid inlet means at the inlet end of said interaction chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to'said longitudinal axis of said chamber,

said interaction chamber being of flattened configuration bounded by a pair of spaced walls between the ends defining its narrow dimension and by another pair of spaced walls between its said ends de fining its greater dimensions,

said other pair of spaced walls having opposite diverging and succeeding converging portions for guiding fluid therealong and terminating at a single outlet passageway through which said total flow is delivered,

said interaction chamber at its narrow dimension being of predetermined height between said inlet end and said outlet end,

a fluid receiving chamber with which said outlet passageway is in comminication, and the height of said fluid receiving chamber being greater than twice the height of said interaction chamber. t 8. A fluid interaction device as defined in claim 7 .in which said fluid receiving chamber is of greater width than the maximum width of said interaction chamber. 9. A fluid interaction device as defined in claim 7 in which means is provided responsive to the direction of flow from said outlet passageway. 10. A fluid interaction device as defined in claim 7 in which said outlet passageway has a diverging discharge portion. 11. A fluid interaction device as defined in claim 10, in which a fluid divider is provided beyond said outlet passageway for directing the flow therefrom.

Claims

1. A fluid interaction device for comparing fluid pressures which comprises a chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying fluid pressures to be compared, fluid inlet means at the inlet end of said chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber, said chamber having a single outlet opening at said outlet end thereof discharging the algebraic sum of the flow in said connections, and means for amplifying the output from said outlet opening, said amplifying means including a fluid outlet, one of said fluid inlets being connected to said fluid outlet of said fluid amplifier in phased relation for negative feedback whereby the pressure supplied to said fluid outlet will follow closely the pressure applied to the other of said fluid inlets.

2. A fluid interaction device as defined in claim 1 in which said amplifying means includes a fluidic device.

3. A fluid interaction device as defined in claim 1 in which means is provided for biasing the negative feedback action to supply to one of said fluid inlets all the fluid required for delivery through said outlet opening.

4. A fluid interaction device for comparing fluid pressures which comprises a chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying fluid pressures to be compared and the total fluid flow to said chamber, and fluid inlet means at the inlet end of said chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber, said chamber having a single flow passageway at said outlet end thereof through which said total flow passes and said passageway having a flow resistance greater than that of either of said fluid supply connections for limiting the pressure drop in said supply connections.

5. A fluid interaction device as defined in claim 4 in which said fluid passageways are in opposed and aligned relation to each other.

6. A fluid interaction device for comparing fluid pressures which comprises a chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying flUid pressures to be compared and the total fluid flow to said chamber, and fluid inlet means at the inlet end of said chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber, said chamber having a single flow passageway at said outlet end thereof through which said total flow passes, said passageway having an effective cross sectional area smaller than the effective cross sectional area of either of said fluid connections for limiting the pressure drop in said supply connections.

7. A fluid interaction device for comparing fluid pressures which comprises an interaction chamber having an inlet end and an outlet end with the longitudinal axis of the chamber therebetween, a first and second fluid connection supplying fluid pressures to be compared and the total fluid flow to said interaction chamber, fluid inlet means at the inlet end of said interaction chamber communicating with both said fluid connections and including fluid passageways each with its longitudinal axis in intersecting relation with respect to said longitudinal axis of said chamber, said interaction chamber being of flattened configuration bounded by a pair of spaced walls between the ends defining its narrow dimension and by another pair of spaced walls between its said ends defining its greater dimensions, said other pair of spaced walls having opposite diverging and succeeding converging portions for guiding fluid therealong and terminating at a single outlet passageway through which said total flow is delivered, said interaction chamber at its narrow dimension being of predetermined height between said inlet end and said outlet end, a fluid receiving chamber with which said outlet passageway is in comminication, and the height of said fluid receiving chamber being greater than twice the height of said interaction chamber.

8. A fluid interaction device as defined in claim 7 in which said fluid receiving chamber is of greater width than the maximum width of said interaction chamber.

9. A fluid interaction device as defined in claim 7 in which means is provided responsive to the direction of flow from said outlet passageway.

10. A fluid interaction device as defined in claim 7 in which said outlet passageway has a diverging discharge portion.

11. A fluid interaction device as defined in claim 10, in which a fluid divider is provided beyond said outlet passageway for directing the flow therefrom.