US2666618A

US2666618A - Rotary throttle blade design

Info

Publication number: US2666618A
Application number: US107490A
Authority: US
Inventors: John S Jaquith
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1949-07-29
Filing date: 1949-07-29
Publication date: 1954-01-19
Anticipated expiration: 1971-01-19

Description

Jan. 19, 1954 J. s. JAQUITH 2,666,618

ROTARY THROTTLE BLADE DESIGN Filed July 29, 1949 FIGB V ,6

@MA l "w I6 l v A INVENTOR. 6 JoH/v s. Mau/TH y BY 'Y I8 Patented Jan, 19, 1,954

UNITED STATE-is PArsNrorFlcE ROTARY THROTTLE BLADE DESIGN John S. Jaquith, Caldwell, N. J., assignor to Bcndix Aviation Corporatio corporation of Delaware Application July 29, 1949 Serial No. 107,490 2 oiarms. (o1. 25a-rs) The present invention relates to throttles for rotary turbines, and more specifically to the contour and design of the throttle blades.

The invention finds particular utility in high velocity aircraft and in accessories therefor, such as ram airrdriven power supplies, for example, Where it is desired to .throttle and control the ram flow propelling a rotor.

in installations of the type where a plurality of circularly disposed fixed vanes guide a ram air stream against the buckets of a turbine wheel to turn said wheel, anda rotary throttle is actuated by a motor to control the ingress of said stream to said vanes, for example, the design of the contour of the throttle blades is of paramount importance, for these are 'subject to sudden, and often, unpredictable load reversals, .high frictional drag, compressib'ility effects, 'shock wave loads, and other aerodynamic disturbances characteristic of transonic land supersonic speed.

In conventionalrctary throttling valves, the blades thereof are usually in the form of triangular prisms, i. e., in cross section the blade is substantially triangular in form having a base portion adjacent the nozzle block and 'sides that converge inwardly toward each 'other to meet at the apex of the triangle. Thus, the blade is `provided with` a relatively sharp edge that splits 'or divides the incoming airstream and causes it 'to flow over the side surfaces of the blades.

When the throttle valve is in open position the air stream passes from the yside surfaces of the blade into the throat ofthe nozzles, i. e., the spaces between the stators of the nozzle block. Since the area of the throat of the nozzles is substantially less than the area dened betweentwo adjacent apices of theblades, it is apparent that as the airstream enters the throat its velocity is increased with a result that the pressure of thev aix-stream decreases. Ihis phenomena is referred to in the art as Bernoulli eifect."

In instances where vthe stators ofthe nozzle block defining the nozzles are symmetrically disposed about an axis parallel to the airstream, in the open position of thethrottle, the airstream splits or 'divides and passes into the nozzle'throat Without materially I affecting the blades ofthe throttle. However, it has been found that where the stators are unsymmetrical so as to denne curved or 'sinuous nozzles, the pressure of the air stream acting on the sloping sides of-the blade are unequal and therefore produce an .unbalf anced force tending to rotate throttle.

Moreover, vit 'fhas been mfound heretofore that in the operation'o'f :adevice `of Vthe above-,indi-l n, 'Teterbora N. J., a

J2 cated character, as the motor actuates `the throttle from full open to full fclosed position, the load `due .to Bernoull-i effect will in some instances suddenly reverse itself in some intermediate posi- Y tion proximate -to the two-third open position,

thereby causing .instability at the point of re versal and irregularity `of the throttle operation, and necessitating a driving system free of backlash, and accordingly, more complicated `and expensive, to overcome this condition.

It is, therefore, vone of the objects -of the pres ent invention to provide a novel type -of throttle blade wherein the foregoing ydisadvantages are substantially eliminated and to do so by novel and effective means.

Another object .of the .invention is to provide a novel type blade fora rotary ram air throttle, and upon which the throttle l'o'ad due to Bernouli-i effect will be reduced to -aminimum `Still another object of the inventionA is to pro-y vide a blade for a rotary ram air throttle free of instability due to the reversing of the load thereon by maintaining the load always in one direction.

Still another object of the invention is to provide a novel type of throttle blade .for a rotary ram air throttle which will permit the throttle to be actuated by relatively lighter and llowerpowered driving means.

The foregoing and other objects and advantages will appear more fully hereinafter from a Vconsideration of the detailed description which' tion is illustrated by way of example. It is to be' expressly understood, however, that the drawings are for the purpose of illustration only, and :are not to be construed as -dening the limits of the' invention. l f

Referring to the drawing wherein like reference characters :designate like parts,

Figure l shows a front View of a rotary throttle.

` Figure 2 is a section through one yof `the blades along the line 2-2 of Fig. 1.

Figure 3 isa schematic drawing showing the throttle blades in operating relation to the vanes and to the turbine wheel.

. VReferring now to the drawings and more partic-ularly to Figures 1 and 3, a rotary throttle, generallyindicatedl by the figure Ill comprises a series of blades l2- adapted by rotary motion tov As shown in Fig. 2, the blades are substantially in the form of a triangular prism having a base portion I9 that is designed to close the nozzle spaces I4 in the block i6 and an apex or edge 22 that is adapted to project into and split the air stream S so as to pass it over the sloping sides 24 and 2B of the blade I2. The side 24 of the blade I2 is so contoured that adjacent the base I9 it merges or blends into the base I9 to form a knife-like edge 28. On the other hand, the side 26 of the blade I2 terminates short of the base I9 in a step 3!! to the end that a flat surface 3l normally disposed to the base I9 is provided. Since this edge of the blade I2 cuts across the air stream entering the throat 2I during rotation of the valve in a closing direction, it is usually termed the leading edge of the blade. Thus, the blade I2 is provided at one edge of the base thereof with a flat surface 3I that is exposed to the pressure of the airstream flowing through throat 2l, while the opposed edge of the base is provided with a relatively sharp knife-like edge 28 that is exposed to the pressure of the airstream flowing through the next adjacent throat 2 I. Since the flat surface 3l is normal to the air stream, it is apparent the Bernoulli elect thereon will be greater than the Bernoulli effect on theknife-like edge 28, and thus a regulating load is placed on the blade I2.

As the blades I2 move from fully open position in the direction of the arrow A, the air stream strikes the tips of apices 22 of the blades and separates on either side of the blade I2, thereby creating a pressure distribution over the side surface 24 and the knife-like edge 28 on one side of the blade I2 and the side surface 2B and at surface 3i on the other side of the blade I2.

In normal operation with the throttle partially closed as shown in Figure 3, the velocity of the air stream S across the narrow throat 2| is relatively higher than the velocity across the remainder of face 26 and face 24. This effect causes the force on face 26 to be lower than the force on the corresponding portion of the sloping surface on the opposing side 24. The net component force on face 24 will thereby -tend to further close the throttle.

It will now be apparent to those skilled in the art that as the stream S passes over the blades I2, the pressure will always be greater on theV surface 24 containing a knife-like trailing edge, since said edge will present only a small area for Bernoulli effect to act upon. The leading edge 30 is of sufficient thickness so that the load, during movements of the throttle from open to closed position, will always over-balance Bernoulli effect in the opposite direction.

It is further apparent that by regulating the height 32 of the step 30, the differential in pres-y sure on the

surfaces

24 and 26 may be further regulated and controlled.

In this manner, the throttle is susceptible vof being driven by far less powered driving means than would ordinarily be employed without regulating the Bernoulli effect to aid the driving means. The step 30 in the leading edge of the blade negates the possibility that the load on the blade, due to Bernoullieffect, will reverse ltself while the blade is in an intermediate position between full open and full closed throttle.

This regulation of the `load uni-directionally re-I sults 1n a more stable and smoother throttle-' There are thus provided means for regulating the actlon of the Bernoullieect. QVQI the. blades.

of a rotary throttle controlling a ram air stream which are positive and reliable in operation, which improve the performance of the remaining components of the turbine, and which are simple and economical to manufacture.

While only one embodiment and one application of the invention has been illustrated and described, other changes and modifications of the form and relative arrangement of parts, which will now be apparent to those skilled in the art, may be made without departing from the spirit and scope of the invention.

What 'is claimed is:

1.. In the combination of a plurality of fixed, spaced stators defining sinuous inlet nozzles therebetween to receive and direct an airstream to a turbine wheel and a rotary throttle valve having a plurality of spaced blades, each blade being individual to and coacting with one stator and the inlet nozzle defined by that stator and the next adjacent stator in the direction of rotation of the turbine wheel, each blade effective on rotation of the throttle valve relative to the stator to move relative to its coacting inlet nozzle to vary the effective area thereof, an improved blade for the rotary throttle valve, said blade comprising a substantially prismatic body having a base adjacent its coacting stator and inlet nozzle and a relatively sharp apex extending into the airstream, the sloping surface between the apex and one side of the base terminating short of the base in a step having a first fiat surface normal to the' base and a second flat surface between the rst flat surface and the sloping surface and parallel to the base and the sloping surface between the apex and the other side of the base merging into the base to form a knife-like edge with the base.

2. In the combination of a plurality of xed; spaced stators defining sinuous inlet nozzles theref between to receive and direct an airstream to a turbinewheel and a rotary throttle valve having a plurality of spaced blades, each blade being individual to and coacting with one stator and the inlet nozzle defined by that stator and the next K adjacent stator. in the direction of rotation of tho turbine wheel, each blade effective on rot-ation of the throttle valve relative to the stator to move relative to its coacting inlet nozzle to vary the effective area thereof, an improved blade for the rotary throttle valve, comprising a body substantially triangular in cross section and having the base thereof adjacent its c-oacting stator andv inlet nozzle, a step formed on said body at one end of the base and having a first flat surface extending forwardly from and normal to the base and a second fiat surface extending normally from the first flat surface toward the opposite end of the base and parallel thereto, a knife-like edge formed on said body at the opposite end of the base,an'd side surfaces extending forwardly from the second flat'surface of said step and said knifelike. edge and converging toward each other to meet andform a relative sharp-edge for said body, said step forming the leading edge of said blade when said blade moves across the inlet nozzle to decrease the elective area thereof.

, A. l W JOHN s. JAQUiTH.

Y neferenqes Cited in the fue of this patent Number Name Y Date 801,345 Svoboda oct. 1o, 1905 $62611 Schulz @Ci-e190?-