US3080711A - Penshape exhaust nozzle for supersonic engine - Google Patents

Description

Maul 12, 1963 .1. F. CONNORS 3,080,711

BENSHAPE EXHAUST NOZZLE FOR SUPERSONIC ENGINE Filed Jan. s, 1960 4 Sheets-Sheet 1 INVENTOR JAMES F. CONN ORS ATTORNEY March 12, 1963 J. F. CONNORS PENSHAPE EXHAUST NOZZLE FOR SUPERSONIC ENGINE Filed Jan. 6, 1960 4 Sheets-Sheet 2 INVENTOR JAMES F. CONNORS ATTORNEY March 1 1963 J. F. coN

PENSHAPE EXHAUST NOZZLE FOR SUPERSONIC ENGINE Filed J 6 196 4 Sheets-s 5 ATTORNEY March 12, 1963 J. F. CONNORS 3,080,711

PENSQHAPE EXHAUST NOZZLE FOR SUPERSONIC ENGINE Filed Jan. 6, 1960 4 Sheets-Sheet 4 FIG .9

FIG]

u. i I g INVENTOR JAMES F. CONNORS ATTORNEY Stats The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to internal external expansion exhaust nozzles for supersonic air-breathing and rocket-type jet engines.

I Previous to the present invention, conventional nozzle configurations consisted of the convergent-divergent nozzle, the plug-type nozzle, and the ejector nozzle. Each of these three nozzles has serious disadvantages. The convergent-divergent nozzle exhibits good performance at design conditions, but the oil-design characteristics indicate severe thrust losses at less than the design pressure' ratio. In the over-expanded nozzle condition, the local pressures along, the-expansion surface drop below ambient pressure, thereby creating drag on the nozzle while the plug-type nozzle geometry utilizes external ex- ;p ansion and maintains, atleast in quiescent air, a high level at performance independent of the pressure ratio. It appears .to have an extremely difficult cooling problem because of the large centerbody which is completely .su-bmerged in the= hot gases emitted. in the jet stream. External stream effects and base. drag due to high lip ,angles are excessive with this type of geometry. The .ejector nozzle gives good performance but tends to be heavy and requires additional ducting of secondary or tertiary air around the engine} The present inventiomconcerns a novel exhaust nozzle having circular end projections more particularly defined asa penshape exhaust nozzlehaving excellent offdcsign characteristics. The instant invention also admits of eacil'y' controllable throat area modulation which is i eguired to-satisfy .a wide range of engine operating conditions; The thr oat area modulation is caused in the ,invntion by either a movable single or double-ramp structure situated. within the nozzle exit'or a movable f clamshellelement, situated at the lip of the nozzle exit. any means of the movable structures within the nozzle exit or tlieclarnshell element, the disadvantages present in the prior nozzle configurations have been eliminated.

An object of the invention is to provide a nozzle exit [capable of attaining high nozzle efljcie'ncies.

Another, object of the invention is a nozzle exit designed to obtain high thrust coefiicients over a wide range of nozzle pressure. ratios and fiightconditions.

rear

-mass flow decreases at a given outlet jconditionfi To'ac- An. additional .objectof .the. invention-is a nozzle that iuachieves the favorable externalexpansion of features of a plug nozzle withoutthe cooling diificulties of a submerged ;-central body.

A further objectof theinvention is an exhaust nozzle --with a exit wherein the afterbody lift drag is considerably panying' drawings in 'which:'

FIGS. 1a-1c diagrammatically shows the- Prandtl-j 'the desired throat area modulation. the clamshell element 21 can be actuated by' any conventional means, such as 22 shown.

Ice

Meyer flow expansion and its application to the penshape exhaust nozzle exit.

FIG. 2 is a penshape exhaust nozzle exit having a clamshell element.

FIG. 3 is a cross-section view of the exhaust nozzle shown in FIG. 2.

FIG. 4 is a cross-section view of a penshape exhaust nozzle having a variable ramp.

FIG. 5 is a pictorial view of the exhaust exit shown in FIG. 4 wherein the ramp is in a closed position.

FIG. 6 is a pictorial view of the exhaust nozzle shown in FIG. 4 having the ramp in an open position.

FIG. 7 is a partly-sectioned pictorial view of a pensha'pe exhaust nozzle exit having a two-dimensional variable ramp.

FIG. 8 is a cross-section taken along line 8-8 0t FIG. 7.

FIG. 9 is an end view of FIG. 7.

Referring now to the drawings wherein like reference characters designate like or corresponding parts throughout the several views. The design approach of the penshape nozzle exit is illustrated in FIGS. la-lc. The well known Prandtl-Meyer theory for determining flow ex,- pansion around a corner, as shown in FIG. 1a, is the basis for calculating the nozzle contours. If the flow is expanded all externally, as seen in the nozzle exitof FIG. 1b, the focal point of the wayesf is located at one end of the sonic line M=1, where M represents jg located on opposite surfaces. Thisftechnique permits lower base angles on the cowl, particularly for extremely high pressure ratios. Thus, from a known flow. field, nozzle contours for an arbitrary cross-sectional" shape of the jet stream tube can be determined by tracing strfea'rn lines back to the throat or sonic area. In FIGS. lalc, the angle zx is the Mach angle at Mach M FIG. 2 shows the exhaust nozzle 23 with a clarnshell element 21 which serves as a varying lip and'thus achieves As seen in FIGQQ,

The nozzlejis readily cooled by bringing cooling air into [the area bounded by the outer shell or surface 17 of the nozzle 23, and the inner surface 18 and exits through opening 20.

v 7 As can be seen in FIG. 3, the exhaust from the .afterburner enters to the left of the exhaust nozzle 23, and when the afterburner is on, the temperature increasesand count for the corresponding decrease in'xde'nsity and to avoid decrease in mass flow, it is necessary toopenfthe lthroat area by moving the clamshell element 21.] By

having such modulation the exhaust stream will be "continually split about two focal points and the drag Will be kept minimum throughout varying operati on- .ditions. a w.

- shaped member 28 beingis actuated from anopen positron in the exhaust nozzle 2.3 wherein said member 28 -1s flush with the expansion surface 48, as seen in'FIG..6,

to a closed'position, as senin FI G.-5r estricting the-clichtive throat area. Cooling air is readily admitted between the area bounded by the inner surface 18 and the outer shell 17 of the nozzle 23; the cooling air exiting through an opening 20, in the outer shell 17.

The penshape nozzles shown in FIGS. 26 may be more particularly defined as comprising an outer shell or outer surface 17 which coacts with inner surface 18 to form a penshape exhaust nozzle 23. The forward end 19 of outer surface 17 and the forward end 24 of inner surface 18 are of generally circular cross section, although not limited thereto, and concentric about longitudinal centerline or axis 25 of the exhaust nozzle 23. In the penshape nozzle shown in FIG. 3 the inner surface 18 and outer surface 17 cooperate to form in part a solid portion 45. The forward end 24 of inner surface 18 defines an exhaust gas passage 42 which is substantially cylindrical and concentric about centerline axis 25. Inner surface 18 and inner surface 18" converge toward each other downstream of front end 24 to form a converging exhaust passage, the passage terminating as a tipped minimum area nozzle throat 43 near the middle portion 46 of nozzle 23. The nozzle throat 43 is substantially, maximally positioned, diametrically opposite the longest straight portion 44 of the outer shell 17, and is tipped with respect to centerline 25 and longest straight portion 44 so that the extension of throat plane 43 defines acute angle a therewith and the downstream portions thereof. Surface 18" terminates as an exit lip 47 downstream of middle portion 46. The rearward or downstream expansion surface 48 of inner surface 18 diverges with respect to the exit lip 47 and terminates downstream of the throat 43 as inner surface point portion 49. Downstream of the throat 43, straight portion 44 terminates in outer end portion 51 which has a common trailing end 52 with inner surface point portion 49. In other words, the straight portion 44 terminates as a trailing end 52 in cooperation with downstream inner surface 49 of inner surface 18. Inner surface 18 also includes connecting portions 53 and 54 which smoothly join the inner surface 18' to the inner surface 18" and which connecting portions also smoothly join exit lip 47 with end 52. By virtue of this construction, inner surface 18 defines gas passage 42 concentric about centerline 25 at its forward end, eccentric to centerline 25 at its middle portion 46 diametrically positioned with respect to straight portion 44 and then defining a divergent gas expansion surface with respect to lip 47 terminating in a substantially elliptic gas outlet 55, thus providing penshape nozzle 23. For the penshape configuration shown in FIGS. 2 and 3, the throat area and plane location thereof is varied by actuation of a clamshell member 21. The downstream surface 48 of inner surface 18 which includes the surface of tear-shaped member 28 of the configuration shown in FIGS. 4-6 is selectively varied by actuation of the tear-shaped member actuating means 29. Outer surface 17 has surface 56 converging longitudinally toward centerline 25 to join with surface 18" and terminates as lip 47 and defines substantially pointed boattail 57. The convergence of surface 56 is of equal or greater angularity than the convergence of surface 48. Connecting portions 58 and 59 of outer surface 17 join exit lip 47 to end 52 as best shown in FIGS. 2, and 6 so that outer surface 17 and inner surface 18 coact to define substantially elliptical exhaust gas outlet edge 55.

Shown in FIGS. 7, 8, and 9 is another embodiment of an exhaust nozzle 32. The nozzle 32 has an outer shell 33 which encloses a double-ramp structure 34, said double-ramp structure 34 being an envelope having an airfoil profile. The trailing edge 38 of said double-ramp structure 34 comprises the trailing edge of said exit nozzle 32. A portion of said double-ramp structure 34 is flexible and extends from two hinges 35 that are adjacent the trailing edge 38 to two guide rods 41 adjacent t ,the leading edge whereby the guide rods 41 move eecording to the expansion and contraction of the section of the double-ramp structure 34. Said movable section of said double-ramp structure 34 is caused to contract or expand by any conventional means 36 placed within the area enveloped by the ramp structure 34. As the ramp structure 34 expands, the guide rods 41 move in a direction towards the trailing edge 38 and are kept parallel to one another at a constant distance by guide runners 37. As the ramp structure 34 contracts, said guide rods 41 move in a direction opposite from the trailing edge 38. The guide rods 41 may be spring loaded (not shown) so as to facilitate the return from the position when the ramp is expanded back to the position of said rods 41 when the ramps are in a contracted position.

It is pointed out that it is not necessary to use flexible ramps in this double-ramped structure. The same effect could be created through the use of fixed pivot pins and a slide joint using rigid ramps.

It can be seen in FIG. 8 that the exhausting gases are split into two separate streams by means of the airfoil shape ramp 34, the effect being created by two penshape nozzles, similar to the one shown in FIG. 4, mounted side by side. As has been previously pointed out, it is highly desirable to have a variable control of the throat area of the penshape exhaust nozzle. This is accomplished, as shown in FIGS. 7, 8, and 9 by means of the expandable air-foil shaped double-ramp structure 34, which structure creates a convergent-divergent effect on the exhaust gases and thus serves as an internal expansion surface.

As can be readily seen, the effect of the variable ramp nozzle is that there are two semi-circular jets and a backto-back nozzle effect. Side force components, therefore, at less than the design pressure ratio would be cancelled by this back-to-back nozzle approach. It should be noted that cooling air can be readily admitted to the interior of the ramp structure 34.

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

In the claims: 1. An exit nozzle comprising an exit lip, a trailing end, said end being diametrically and longitudinally positioned with respect to said lip,

an outer shell joining said lip and said end, said outer shell comprising a surface which is symmetricalwith respect to the longitudinal centerline of said shell, the symmetry occurring in planes which are perpendicular to the longitudinal centerline of said shell, said surface providing anexhaust outlet having a substantially elliptical edge and having said lip and said end at the limits of the major axis thereof,

an upstream inner surface disposed within said shell,

said inner surface effecting a convergent flow area terminating as a nozzle throat diametrically and longitudinally positioned with respect to said end, and

an expansion surface disposed in said shell downstream of said throat, said expansion surface comprising a concave central surface interconnecting said throat and said trailing end and symmetrical concave surfaces with respect to the shell centerline interconnecting the exhaust outlet elliptical edge of said outer shell with said concave central surface and said throat.

2. An exhaust nozzle, according to claim '1, wherein the said lip has an inward curvature toward said trailing end.

3. A penshape exhaust nozzle comprising an outer surface,

said outer surface being substantially straight-on one longitudinal line thereof and extending for thefull exhaust nozzle length and terminating in a trailing end, a

said outer surface further having a curved surface diammetrically and longitudinally positioned with respect to said end converging gradually toward said straight surface and terminating in an exit lip substantially short of the trailing end, and

said outer surface still further having connecting surfaces joining said straight outer surface and said curved surface so that said outer surface has a substantially rearward elliptical edge outlet, and

an inner surface,

said inner surface defining an exhaust gas passage having a substantially circular cross section at its forward end and converging to a minimum area exit throat, said throat being diammetrically positioned with respect to said straight outer surface at a substantially maximum distance therefrom and terminating upstream of said trailing end,

said inner surface throat further having the plane thereof defining an acute angle to said straight outer surface with respect to said trailing end, and

said inner surface still further having an expansion surface rearward of said throat and converging toward said straight outer surface and terminating at said trailing end, said expansion surface also terminating in communication with the elliptical edge outlet and said throat.

4. Apparatus, according to claim 3, and including a member pivotally attached to said curved surface and being pivotable toward said straight outer surface thereby permitting selective variation of the exit throat area.

5. Apparatus, according to claim 4, and including actuating means to selectively pivot said pivotable member toward said straight outer surface.

6. Apparatus, according to claim 3, and including a movable member disposed in said expansion surface and being movable toward said exit lip thereby permitting selective variation of the exit throat area.

7. Apparatus, according to claim 6, and including actuating means to selectively move said movable member toward said lip.

References Cited in the file of this patent UNITED STATES PATENTS 2,683,962 Griflith July 20, 1954 2,788,635 Ford Apr. 16, 1957 2,802,333 Price et a1 Aug. 13, 1957 2,928,235 Johnson Mar. 15, 1960 2,939,274 Olson June 7, 1960 2,952,124 Pearson Sept. 13, 1960 2,956,759 Creasey et a1 Oct. 18, 1960 3,019,601 Sens Feb. 6, 1962

Claims (1)

1. AN EXIT NOZZLE COMPRISING AN EXIT LIP, A TRAILING END, SAID END BEING DIAMETRICALLY AND LONGITUDINALLY POSITIONED WITH RESPECT TO SAID LIP, AN OUTER SHELL JOINING SAID LIP AND SAID END, SAID OUTER SHELL COMPRISING A SURFACE WHICH IS SYMMETRICAL WITH RESPECT TO THE LONGITUDINAL CENTERLINE OF SAID SHELL, THE SYMMETRY OCCURRING IN PLANES WHICH ARE PERPENDICULAR TO THE LONGITUDINAL CENTERLINE OF SAID SHELL, SAID SURFACE PROVIDING AN EXHAUST OUTLET HAVING A SUBSTANTIALLY ELLIPTICAL EDGE AND HAVING SAID LIP AND SAID END AT THE LIMITS OF THE MAJOR AXIS THEREOF, AN UPSTREAM INNER SURFACE DISPOSED WITHIN SAID SHELL, SAID INNER SURFACE EFFECTING A CONVERGENT FLOW AREA TERMINATING AS A NOZZLE THROAT DIAMETRICALLY AND LONGITUDINALLY POSITIONED WITH RESPECT TO SAID END, AND AN EXPANSION SURFACE DISPOSED IN SAID SHELL DOWNSTREAM OF SAID THROAT, SAID EXPANSION SURFACE COMPRISING A CONCAVE CENTRAL SURFACE INTERCONNECTING SAID THROAT AND SAID TRAILING END AND SYMMETRICAL CONCAVE SURFACES WITH RESPECT TO THE SHELL CENTERLINE INTERCONNECTING THE EXHAST OUTLET ELLIPTICAL EDGE OF SAID OUTER SHELL WITH SAID CONCAVE CENTRAL SURFACE AND SAID THROAT.

Images