US3566898A

US3566898A - Flueric vortex proportional amplifier

Info

Publication number: US3566898A
Authority: US
Inventors: Kenneth R Scudder; John F Burke; John L Dunn
Original assignee: US Department of Army
Current assignee: US Department of Army
Priority date: 1968-12-20
Filing date: 1968-12-20
Publication date: 1971-03-02
Anticipated expiration: 1988-03-02

Abstract

A flueric vortex proportional amplifier having two concentric rings contained between a top plate and a bottom plate with fluid supply inputs providing a source of fluid between the concentric rings. The inner ring is of a porous material construction such that restricted fluid flow through the porous inner ring causes a nearly uniform pressure to be built up between the two rings to assure substantially irrotational radial flow within the chamber formed by the inner porous ring and the top and bottom plates. Concentric with the vortex chamber and in each end plate is a fluid output drain having an airfoil positioned therein and extending from the drain wall to the center of the drain with the chord of the airfoil being parallel with the axis of the drain. Downstream of the airfoil and in an expanded section of the drain, two normal splitters divide the drain into four equal outputs. The two outputs directly under the airfoil are the amplifier outputs. Two tangential control nozzles are positioned within the chamber with the output slots thereof facing in opposed tangential directions.

Description

United States Patent [72] Inventors Kenneth R. Scudder Saint Leonard; John F. Burke, Beltsville, Md.; John L. Dunn, Fairfax, Va.

[21] Appl. No. 785,544

[22] Filed Dec. 20, 1968 [45] Patented Mar. 2, 19 71 [73] Assignee the United States of America as represented by the Secretary of the Army [54] FLUERIC VORTEX PROPORTIONAL AMPLIFIER 5 Claims, 4 Drawing Figs.

Primary Examiner-Samuel Scott Attorneysl-larry M. Saragovitz, Edward J Kelly, Herbert Ber] and J D. Edgerton ABSTRACT: A flueric vortex proportional amplifier having two concentric rings contained between a top plate and a bottom plate with fluid supply inputs providing a source of fluid between the concentric rings. The inner ring is of a porous material construction such that restricted fluid flow through the porous inner ring causes a nearly uniform pressure to be built up between the two rings to assure substantially irrotational radial flow within the chamber formed by the inner porous ring and the top and bottom plates. Concentric with the vortex chamber and in each end plate is a fluid output drain having an airfoil positioned therein and extending from the drain wall to the center of the drain with the chord of the airfoil being parallel with the axis of the drain. Downstream of the airfoil and in an expanded section of the drain, two normal splitters divide the drain into four equal outputs. The two outputs directly under the airfoil are the amplifier outputs. Two tangential control nozzles are positioned withinthe chamber with the output slots thereof facing in opposed tangential directions.

' PATENTEUHAR 21am E 3566398 INVENTORS KENNETH R. SCUDDER JOHN F. BURKE JOHNL. DUNN ATTORNEYS F LUERIC VORTEX PROPORTIONAL AMPLIFIER BACKGROUND OF THE INVENTION This invention relates generally to pure fluid devices for amplifying a fluid pressure input, and more particularly to a flueric vortex proportional amplifier having a substantially linear push-pull output.

The state of the art of pure fluid devices has been considerably advanced since the basic fluid amplifiers were built and tested at the Harry Diamond Laboratories in 1959. One example of the extent to which the-state of the art has advanced is in the development of an all-fluid no-moving parts attitude control system for a missile which takes the error signals of an attitude-sensing device and modulates and amplifies these signals to ultimately control the attitude of the missile. Since the control system is designed to be all fluidoperated and without moving parts, the output from the attitude-sensing device must be in the form of fluid signals and an amplifier associated therewith must be a pure fluid device in order for the sensor and amplifier to be compatible with the rest of the system.

One type of pure fluid attitude sensor that has been used to supply the error signals for a missile control system is the fluid angular rate sensor disclosed by Scudder et al. in patent application Ser. No. 524,358, now U.S. Pat. No. 3,365,955, issued Jan. 30, 1968, and assigned to the assignee of the instant application. The Scudder et al. rotation sensor is a vortex rate sensor having a fluid output which operates on the principles of vortex motion. It is essential in a pure fluid system that the amplifier associated with such a pure fluid rotation sensor having a fluid output also be a pure fluid device which is compatible to the rate sensor and the overall fluid system.

The operation of a vortex rate sensor can be easily understood by considering a relatively flat cylindrical chamber having a relatively small central drain or output passage therein to which fluid under pressure such as air is supplied at or near the circumference of the chamber. The chamber is provided normally with an annular ring or coupler made of a porous material such that fluid flowing through the coupler will have only a radial component of velocity. When the rate sensor is rotated in a plane perpendicular to its axis, a tangential component of velocity is imposed on the fluid as it leaves the coupler whereby vortex flow is produced in the chamber and helical flow is produced in the drain. Because of the conservation of angular momentum, the tangential velocity of the flow and consequently the velocity of the fluid in the vortex increases as the fluid reaches the drain, thereby providing an amplification factor for the sensor. By appropriately sensing the flow parameters in the drain, particularly the changes in the helical angle, the angular rate of the sensor can be determined.

The beforementioned Scudder et al. US. Pat. No. 3,365,955 discloses an improved fluid readout means for a vortex rate sensor which consists basically of a slotted cylinder positioned in the drain of the rate sensor, with its axis transverse to the drain axis. The slots are located in the upstream portion of the cylinder and are at a very small radius from the drain axis. As the helical angle of the flow through the drain changes, due to change in rotation of the rate sensor, the static pressure at the slots changes, and the pickoff produces a fluid output signal which is proportional to the angular rate of rotation of the sensor. Increased sensitivity of the readout means could be achieved by introducing an airfoil section upstream of and in close proximity with the slotted cylinder.

It is essential that the amplifier utilized in conjunction with a pure fluid angular rate sensor, such as that disclosed in the Scudder et al. patent, be of a pure fluid nature having an input compatible with the output of the rate sensor and an output of a pure fluid nature. It is desirable that such an amplifier have a low pressure gain and a high flow gain and that the inputs of the amplifier be a match for the high-impedance output of a rate sensor such as thatdisclosed in the Scudder et al. patent while the the outputs of the amplifier be a match for a low-impedance device. It is further desirable that the output of the amplifier be of a substantially linear push-pull type.

At this point, it would be useful to consider briefly the properties of vortex sink flow, so that the invention can be more readily understood.

Vortex motion can be divided into two distinct types of motion, the forced vortex and the free vortex. The forced vortex occurs when all particles of the fluid have the same angular velocity and, therefore, the tangential velocity, V,, is directly proportional to the radius. This is equivalent to solid body or wheellike rotation and is sometimes referred to as rotational flow. As the radius increases, the tangential velocity increases linearly. In the free vortex where the flow is irrotational, the tangential velocity V, varies inversely with the radius. Also, the centrifugal force decreases with increasing radius. Both of these vortex conditions occur naturally in real vortex motion with certain limitations.

In free inviscid vortex motion conservation of angular momentum is assumed. When the total pressure considered in a vortex, it is seen that free vortex flow cannot occur in practice for very small radii. For example in the incompressible case and for the free vortex V, k/r

where k is a constant.

Now P is a constant and P cannot in practice become negative; therefore, the tangential velocity, V,, cannot exceed the maximum velocity given by The real vortex motion then has both forced vortex motion near its axis and free vortex motion at some distance from its axis. Separating these two regions is a transition region where the tangential velocity reaches a maximum. This tangential velocity distribution is characteristic for all real vortex devices. The maximum tangential velocity, V,, occurs at a small radius from the center which defines a circle called the limit circle. For maximum amplification, therefore, it is desirable to position a pickoff in the vicinity of the limit circle so that the maximum tangential velocity can be sensed.

Fluid amplifiers are well known in the prior art, but such devices although useful in many applications, have not been wholly satisfactory for utilization in a pure fluid system, where it is desirable to have no moving parts and no electronic com: ponents.

SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a new and improved flueric vortex proportional amplifier.

Another object of the invention is to provide a new and improved vortex proportional amplifier having no moving parts.

Still another object of the present invention is to provide a new and improved flueric vortex proportional amplifier that produces fluid output signals which are a match for a low impedance device.

One other object of this invention is the provision of a new and improved flueric vortex proportional amplifier with inputs which are a match for a high impedance device.

A still further object of the present invention is the provision of a new and improved flueric vortex proportional amplifier for amplification of high impedance outputs of a vortex rate sensor.

Still another object of the present invention is the provision of a new and improved flueric vortex proportional amplifier having a high flow gain and a low pressure gain.

One further object of the present invention is the provision.

Briefly, in accordance with one embodiment of this invention, these and other objects are attained by a flueric vortex proportional amplifier having a vortex chamber with a circular cross-sectional area and a centrally located axis, means for introducing pressurized fluid into said chamber with substantially only a radial component of velocity, first control means in the chamber for inducing a counterclockwise tangential component of velocity to the fluid in response to a first input control signal, second control means in the chamber for inducing a clockwise tangential component of velocity to the fluid in response to a second input control signal, and substantially linear push-pull output means for sensing the direction and magnitude of the tangential components of velocity induced by the first and second control means.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention and many of the attendant advantages thereof will be readily appreciated as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a top plan view, partly in section, of a flueric vortex proportional amplifier;

FIG. 2 is a cross-sectional view taken along lines 2-2 of FIG.

FIG. 3 is a cross-sectional view of a portion of the drain tube of a flueric vortex proportional amplifier which shows an airfoil section in combination with a splitter and multiple-flow output means; and

FIG. 4 is a plan view, partly in section, taken along the lines 4-4 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, wherein like reference characters designate identical or corresponding parts throughout the several views, and more particularly to FIGS. 1 and 2 thereof, wherein there is shown a flueric vortex proportional amplifier generally indicated by the reference numeral 10. Amplifier is essentially a relatively flat, hollow, cylindrical chamber that includes a circular top wall 11, a circular bottom wall 12, in spaced parallel relation thereto, and an annular sidewall 13 secured in a fluidtight relation to the top and bottom walls, by any suitable means such as the screws 14. An annular porous ring or coupler 15 is positioned within the chamber of the amplifier at a smaller radius than annular wall 13 and provides a manifold 16 between coupler 15 and annular wall 13. Top and bottom walls 11 and 12, respectively, and annular wall 13 may be constructed of any rigid material such as metal, glass, plastic, or the like, that is compatible with and impervious to the working fluid. Coupler 15 is preferably made of a sintered metal but may be made of any suitable porous material that allows fluid to pass through it with a minimum of restriction. I

Fluid under pressure from a source (not shown) enters amplifier 10 by means of one or more input nozzles 17 formed in the annular wall 13, and leaves the rate sensor by means of a centrally located drain tube 18 provided in the bottom plate 12. A second drain 19 may be provided in the top plate 11 if so desired.

Two

tangential nozzles

22 and 24 are provided within the vortex chamber adjacent to coupler 15 in diametrically opposed relationship. Control nozzle 22 has an elongated slot 26 therein extending substantially the height of coupler 15 so as to introduce an equally distributed fluid pressure input to the vortex chamber in a counterclockwise direction for inducing a counterclockwise tangential component of velocity to the fluid within the vortex chamber. Control nozzle 24 has an elongated slot 28 therein similar to slot 26 in control nozzle 22, but in an opposed tangential direction thereto for inducing a clockwise tangential component of velocity to the fluid within the vortex chamber. The

slots

26 and 28 extend substantially the height of the vortex chamber so as to provide an equally distributed control signal to the fluid within the vortex chamber.

An airfoil 30 is positioned within drain 18, as shown in FIGS. 2 and 3, reaching from the drain wall to the center of the drain with the chord of the airfoil being parallel with the axis of the drain. As shown in FIGS. 2, 3 and 4, two normal splitters are located downstream from the airfoil 30 and in an expanded section of the drain so as to divide the drain into four

equal outputs

44, 45, 46 and 47.

The supply fluid coming through the porous coupler 15 into the vortex chamber and out through the drain 18 is normally radial in the chamber and axial in the drain. Upon receiving a control signal from a pure fluid device such as the outputs of a vortex rate sensor, pressure slightly greater than the chamber pressure is supplied to the

control nozzles

22 and 24 to enter the chamber in a tangential manner through

slots

26 and 28. If a differential pressure is developed across the control nozzles, causing the flow rate of the nozzles to be unequal, a vortex is formed in the chamber and helical stream lines are formed in the drain. The helical stream lines change the angle of attack of the air foil 30 and a differential velocity across the airfoil is developed. The streams on each side of the airfoil converge at the trailing edge and the combined stream deflects toward the low velocity side thereof. The two normal splitters in the drain form two

channels

46 and 47 directly downstream from the airfoil and due to the stream deflection, the flow rate in the channels will differ in proportion to the differential pressure at the control nozzles. The vortex proportional amplifier will function without the airfoil. However, without the airfoil, the gain will be lower, but the signal to noise ratio may be higher. The vortex amplifier is capable of accepting the high impedance inputs from a vortex rate sensor to amplify the rate sensor output signals and produce an output which is a match for a low-impedance device. The flueric vortex proportional amplifier of the present invention hasthe obvious advantages of a push-pull output due to the airfoil and splitter arrangement in the drain 18. The device further exhibits the advantages of high flow gain and low pressure gain.

In dealing with vortex sink flow as with any other kind of fluid flow, it is very important that edges and abrupt changes in the shape of the walls containing the fluid be avoided to reduce turbulence. For this reason, the entrance to the drain tube 18 in the vortex amplifier 10 is shown to have a smoothly curved edge 20 to reduce turbulent effects which, of course, result in the noise in the output signals from the amplifier.

Obviously, numerous modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

We claim:

1. A flueric vortex proportional amplifier comprising:

a vortex chamber having a circular cross-sectional area and a centrally located axis; means for introducing pressurized fluid into said chamber with substantially only a radial component of velocity; first control means in said chamber for inducing a clockwise tangential component of velocity to said fluid in response to a first input control signal; second control means in said chamber for inducing a counterclockwise tangential component of velocity to said fluid in response to a second input control signal,

substantially linear flueric push-pull output means for sensing the direction and magnitude of said tangential components of velocity induced by said first and second control means, said push-pull output means comprising a cylindrical drain passage located at the center of said chamber with the axis of said drain passage coinciding with the axis of said chamber;

double splitter means extending across said drain passage and dividing said passage into four equal output channels; the upstream edges of said splitter means being transverse to the axis of said drain passage; and

said splitter means producing a differential flow in said output channels in response to helical flow in said drain passage resulting from said induced clockwise or counterclockwise flow in said chamber.

2. The flueric vortex proportional amplifier according to claim 1 wherein said first and second control means comprise at least one pair of diametrically opposed control nozzles equidistant from said centrally located axis of said chamber, each of said nozzles having an elongated fluid outlet slot for providing ingress of a control fluid into said chamber with said slots facing in opposed tangential directions.

3. The flueric vortex proportional amplifier according to claim 2 wherein said push-pull output means comprises:

a symmetrical airfoil section possessing a high lift to drag ratio positioned in an expanded portion of said drain passage upstream of said splitter means; said airfoil section being transverse to the axis of said passage; said airfoil section cooperating with said splitter means to deflect said helical drain flow to produce a differential flow across said splitter means; and whereby said differential flow generates high flow output signals in said output channels proportional to said input control signals. 4. A flueric vortex proportional amplifier according to claim 3 wherein said vortexchamber comprises: spaced parallel circular top and bottom walls; an annular sidewall secured in fluidtight relation to said top and bottom walls; and v i an annular porous ring positioned between said top and .bottom walls and of a smaller diameter than said sidewall. 5. A flueric vortex proportional amplifier according to claim 4 wherein said slots in said control nozzles extend substantially the height of said porous ring.

Claims

1. A flueric vortex proportional amplifier comprising: a vortex chamber having a circular cross-sectional area and a centrally located axis; means for introducing pressurized fluid into said chamber with substantially only a radial component of velocity; first control means in said chamber for inducing a clockwise tangential component of velocity to said fluid in response to a first input control signal; second control means in said chamber for inducing a counterclockwise tangential component of velocity to said fluid in response to a second input control signal; substantially linear flueric push-pull output means for sensing the direction and magnitude of said tangential components of velocity induced by said first and second control means, said push-pull output means comprising a cylindrical drain passage located at the center of said chamber with the axis of said drain passage coinciding with the axis of said chamber; double splitter means extending across said drain passage and dividing said passage into four equal output channels; the upstream edges of said splitter means being transverse to the axis of said drain passage; and said splitter means producing a differential flow in said output channels in response to helical flow in said drain passage resulting from said induced clockwise or counterclockwise flow in said chamber.

3. The flueric vortex proportional amplifier according to claim 2 wherein said push-pull output means comprises: a symmetrical airfoil section possessing a high lift to drag ratio positioned in an expanded portion of said drain passage upstream of said splitter means; said airfoil section being transverse to the axis of said passage; said airfoil section cooperating with said splitter means to deflect said helical drain flow to produce a differential flow across said splitter means; and whereby said differential flow generates high flow output signals in said output channels proportional to said input control signals.

4. A flueric vortex proportional amplifier according to claim 3 wherein said vortex chamber comprises: spaced parallel circular top and bottom walls; an annular sidewall secured in fluidtight relation to said top and bottom walls; and an annular porous ring positioned between said top and bottom walls and of a smaller diameter than said sidewall.

5. A flueric vortex proportional amplifier according to claim 4 wherein said slots in said control nozzles extend substantially the height of said porous ring.