In addition to fixed and variable bleed devices provided for controlling the position of a terminal shock wave in a supersonic inlet, a plurality of free piston valves are disposed around the periphery of a cowling of a supersonic engine inlet. The free piston valves are disposed in dump passageways, each of which begin at a bleed port in the cowling that is located in the throat region of the inlet, where the diameter of the centerbody is near maximum, and terminates at an opening in the cowling adjacent a free piston valve. Each valve is controlled by reference pressure

Mitchell, G. A.

Sanders, B. W.

English

NASA Technical Reports Server

REPLY TO
ATTN OF: GP
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
WASHINGTON. D.C. 20546
APR 1 6 1974
TO: KSI/Scientific & Technical Information Division
Attn: Miss Winnie M. Morgan
FROM: GP/Office of Assistant General
Counsel for patent Matters
SUBJECT: Announcement of NASA-Owned U.S. Patents in STAR
In accordance with the procedures agreed upon by Code GP
and Code KSI, the attached NASA-owned U.S. Patent is being
forwarded for abstracting and announcement in NASA STAR.
The following information is provided:
U.S. Patent No. :
Government or
Corporate Employee
Supplementary Corporate
Source (if applicable)
NASA Patent case No.
NOTE - If this patent covers an invention made by a corporate
employee of a NASA Contractor, the following is applicable:
YES NO /Y7
Pursuant to Section 305 (a) of the National Aeronautics and
Space Act, the name of the Administrator of NASA appears on
the first page of the patent; however, the name of^_thfi_actual
inventor (author) appears at the heading of
the Specification, following the words "...wij
an invention of ..."
respect
n
CO
Bonnie L. Woerner
Enclosure
https://ntrs.nasa.gov/search.jsp?R=19740012533 2020-03-17T14:50:10+00:00Z
United States Patent
Mitchell et al.
Hi] 3,799,475
[45] Mar. 26, 1974
[54] AIRFLOW CONTROL SYSTEM FOR
SUPERSONIC INLETS
[75] Inventors: Glenn A. Mitchell, Berea; Bobby W.
Sanders, Brookpark, both of Ohio
[73] Assignee. The United States of America as
represented by the Administrator of
the National Aeronautics and Space
Administration, Washington, D.C.
[22] Filed: June 11, 1971
[21] Appl. No.: 152,328
[52] U.S. Cl 244/53 B, 137/15.1, 137/15.2
[51] Int. Cl B64d 33/02
[58] Field of Search 244/53 R, 53 B; 137/15.1,
137/15.2,511,514.5,514.7
[56]
2,755,040
3,007,481
References Cited
UNITED STATES PATENTS
7/1956 Pinkos et al 244/53 B
11/1961 Frost 137/116
3,067.578 12/1962
3,126,174 3/1964
3.495,605 2/1970
Goodall et al 60/35.6
Zetterstrom et al 244/53 B
Gunnarson et al 137/15.1
Primary Examiner—Duane A. Reger
Assistant Examiner—Barry L. Kelmachter
Attorney, Agent, or Firm—N. T. Musial; J. A. Mackin;
J. R. Manning
[57] ABSTRACT
In addition to fixed and variable bleed devices pro-
vided for controlling the position of a terminal shock
wave in a supersonic inlet, a plurality of free piston
valves are disposed around the periphery of a cowling
of a supersonic engine inlet. The free piston valves are
disposed in dump passageways, each of which begins
at a bleed port in the cowling that is located in the
throat region of the inlet where the diameter of the
centerbody is near maximum and terminates at an
opening in the cowling adjacent a free piston valve.
Each valve is controlled by a reference pressure.
12 Claims, 2 Drawing Figures
10 16
(NASA-Case-LEW-11188-1) AIEFLOW CONTJ80L
SYSTEM FOE SUPERSONIC INLETS Patent
j (NflSA) 6 p CSCL 01B
Unclas
00/02 33974
PATENTED m 2 61974 3.799,475
SHEET 1 OF 2
\
INVENTORS
GLENN A. MITCHELL
BOBBY W. SANDERS
BY
CW/w^—
ATTORNEYS
PATENTEOHAR261974 3.799.475
.SHEET 2 OF 2
a,
CvJ OJ
BY
INVENTORS
GLENN A. MITCHELL
BOBBY W. SANDERS
ATTORNEYS
. . „ . ' • • 3,799,475
* -• 1 . ' 2
AIRFLOW CONTROLSYSTEM FOR SUPERSONIC
 DESCRIPTION OF THE DRAWINGS
.ORIGIN OF THE INVENTS
The invention described herein was made by employ- 5 tion.
ees of the United States Government and may be man- FIG. 2 comprises two quarter axial sectional views of
ufactured and used by or for the Government of the a free piston valve embodied in the invention, FIG. la
United States of America for governmental purposes showing the valve in closed position and FIG. 2b
without the payment of any royalties thereon or there- showing the valve in opened position.
for
 '° DESCRIPTION OF A PREFERRED EMBODIMENT
BACKGROUND OF THE INVENTION Referring now to FIG. 1, there is shown a supersonic
The invention relates to air inlets for supersonic air- air inlet 10 including a centerbody 11 disposed in an
craft engines and is directed more particularly to shock annular cowling 12. The cowling is formed by annular
wave controlling apparatus adapted to prevent the ter- 15 inner wal1 14 and an outer wal1 13-
minal shock wave from being expelled out the front of T*16 desired position for the terminal shock wave as
the air inlet under certain operational conditions such shown at ls is at or near the throat of the air inlet
as a reduction in the amount of required diffuser air- where the diameter of the centerbody 11 is near maxi-
flow or the occurrence of gusts. Such expulsion of the mum-If 8usts or other conditions cause the shock wave
terminal shock wave can result in a complete loss of 20 1S to move ahead of the throat area> the shock wave
thrust and can actually result in a drag component. This may be exPe»ed from the front of the air inlet causing
obviously cannot be tolerated for an aircraft. an unstart condition. To inhibit or prevent the shock
In the prior art, a number of bleed systems have been wave 15 from beinS expelled, air bleeds 8 are provided
utilized in attempts to prevent expulsion of the terminal „ in the throat re8ion on the centerbody 11 and are
shock wave out of the air inlet. One of these methods 2S ducted *TOUZh hollow centerbody support struts 9 to
involves the use of fixed openings or bleeds communi- flxed ** bleed exits ln the Cow!ln8 "»' at 16 a"d a var"
cating with the space between the cowling and the cen- able air bleed system as provided in the cowling as at
terbody. Such arrangements are satisfactory only in a "\The vanable alr bleed system 17 may be of the guil-
very limited operating range. To increased stable op-
 30
 loUn
_
e
 ***_ ^
 shown. As explained previously neither
.. • . , ,. , . ... . . ,
 30
 the fixed bleeds 8, the fixed cowling bleeds of the prior
erating range with a fixed throat bleed exit the perform- . . ' ,. , ,_ • •. ~ „ . ri . , , . , , , , j • i_i art, nor the variable bleed 17 may have sufficient range
ance level of the inlet must be reduced to undesirably ,.' . , . . , , f,
. ii ' of operation to prevent the terminal shock wave 15
A V 11 ui ui j • i from being expelled under certain adverse conditions.A typeof controllable bleed arrangement involves an
 TQ
 B
en/that massive amounts of ajf be
apertured plate d.sposed at the outer surface of the
 35 du from ^ interior of ^ aif ^ t £ ^
cowlmg and a movable plate which may be moved ax-
 cow|ing Qne Qr more free jston ya]ves ,g ^ dis_
ally to open or close the apertures. A shock position
 around ^ rf he of the cowli 12 The free
sensor connected to a computer control is used to hy-
 iston ya,ves lg are di sed at openings of an air pas.
drauhcally control the pos.tion of the movable plate 19 which provides communication between
thereby determining the amount of air bled from the 40
 bleed ports 20 and gates 21.
interior of the cowl and permitted to escape. Such ar-
 The b,eed ports 20 may ^ the fonn of a single an.
rangements are not self-acting and involve expensive
 nular s,ot or a perforated annular wall section. Simi-
computer operated hydraulic or pneumatic controls.
 larly the air passageway 19 may be an annular plenum
Although the controllable type air bleed provides a
 or a plurality of air passageways, each terminating at a
much larger steady state stable operating range than 45
 respective valve 18.
the fixed type air bleed, its ability to control transient Reference pressure for the free piston valves 18 is
air flow changes is nevertheless not as great as required provided through conduits 22 which are connected be-
for conditions encountered in supersonic flight.
 tween the valves 18 and reference ports 23 disposed
SUMMARY OF THE INVENTION
 50
 around
 ^ Periphery of the centerbody 11 just forward
of the normal position of shock wave 15 as shown. With
It is an object of the invention to provide a new and
 shock wave IS in its normal position, that is just to the
novel controllable air bleed system for the inlet of a su-
 rear of reference ports 23, the pressure communicated
personic aircraft engine. through conduits 22 to valves 18 is slightly higher than
It is another object of the invention to provide a con- the pressure in passageway 19. Consequently, the
trollable supersonic inlet bleed system that provides the 55 valves 18 are normally closed,
inlet with a relatively large stable operating range. when gusts or adverse conditions cause the shock
Still another object of the invention is to provide a wave 15 to move forward from the throat area, the air
controllable bleed system which is relatively simple and pressure at the bleed ports 20 increases. This pressure
inexpensive. 60 'ncrease 's communicated through the passageway 19
• Yet another object of the invention is to provide a to the valves 18 causing the free piston valves 18 to
controllable air bleed system which is responsive to a open. Opening of the valves 18 allows massive amounts
substantially constant bleed pressure characteristic of air to enter bleed ports 20 passing through air pas-
control device. sageway 19 past the valves 18 and out through the gates
An additional object of the invention is to provide a „ 21. This prevents the shock wave 15 from being ex-
controllable air bleed system for supersonic inlets pelled out the front of the air inlet and, when the gusts
wherein massive amounts of air flow may be bypassed or unstable condition terminates the valves 18 will
from the throat of a supersonic inlet. again close. An isolator 35 in the conduit 22 insulates
3,799,475
10
15
20
30
the pressure in valves 18 from external changes during
the operation of the valve. Isolator 35 may take the
form of a restrictor or a pneumatic capacitor. A pres-
sure regulator 36 may be disposed in each of the con-
duits 22 and may be of a commercially available type
having a constant pressure inlet communicating with a
reference port 23.
Referring now to FIG. 2a, there is shown a free piston
valve 18 comprising a cylindrical cup 24 and a piston
25 which is provided with a post 26 extending into a
guide 27 of the cup 24. The piston 25 includes an annu-
lar skirt portion 28 which slidably engages the cup 24
when the piston 25 moves axially rearward. A rolling
seal such as flexible member 29 may be disposed be-
tween the skirt of the piston and the cup 24 when the
piston is of substantially smaller diameter than the cup
24. The piston 25 with the cup 24 and the rolling seal
29 form a chamber 30, the volume of which is variable
in accordance with the difference of pressure between
that communicated to the chamber 30 from a reference
port 23 as shown in FIG. 1 and the pressure present in
passageway 19.
The piston 25 is also provided with an axially extend-
ing annular rim 31 which engages an air passageway
rim 32 at the outward end of the passageway 19 when 25
the valve 18 is closed. An annular ring 33 of a suitable
resilient material may be disposed on the rim 32 to im-
prove the sealing engagement of the rim 31 with the
rim 32.
Referring now to FIG. 2b 'there is shown a valve 18
in open position, that is with the skirt 28 of the piston
25 pushed into the cup 24. As indicated previously, this
occurs when the pressure in air passageway 19 exceeds
the pressure in the chamber 30. As shown in FIG. 2b,
the annular rim 31 is separated from the resilient ring
33 allowing a massive amount of air to pass from the
passageway 19 out through the gate 21 as indicated by
the arrow 34; This prevents the shock wave:15 shown
in FIG. 1 from being expelled out the front of the air
intake.
A ball valve 36 retained in a cage 37 which is sup-
ported by a rod 38 extending from piston 25 closes the
opening of conduit 22 at its point of entrance to the
chamber 30 when the valve 18 is opened.
A spring 39 disposed in the cage presses the ball 36
against the opening of conduit 22 as the piston 25 ap-
proaches its opened or retracted position. The ball
valve 36 serves the same function as the isolator 35 of
FIG. 1 and may be used in conjunction with or in place
of the isolator 35.
The rolling seal 29 of the valve 18 as shown in FIGS.
2a and 2b should be sufficiently soft as to provide sub-
stantially zero spring constant for the valve 18. On the
other hand, it should have sufficient stiffness to
dampen oscillations which may occur under certain
conditions. The rolling seal 29 may be eliminated by
making the piston 28 of sufficient diameter to slidingly
engage the cup 24. With this arrangement friction be-
tween the piston skirt 28 and the cup 24 will provide
damping to inhibit oscillations of the piston.
ALTERNATE EMBODIMENTS
The structure described above may be utilized to
minimize local pressure increases in a supersonic air
inlet as may occur due to the reflected shock wave or
due to a change in the angle of attack. The only change
necessary to accomplish this is moving the bleed ports
40
45
50
55
20 and the reference ports 23 to positions well forward
of their respective locations for controlling the terminal
shock. Additionally this arrangement can be used si-
multaneously with the arrangement for controlling the
terminal shock wave.
It will be understood the above-described invention
may be 'changed or modified without departing from
the spirit and scope of the invention as set forth in the
claims appended hereto. ' . •
What is claimed is:
1. A supersonic inlet for a jet aircraft engine compris-
ing:
an annular cowling having an outer wall and an inner
wall forming an air passageway;
a centerbody disposed in said cowling and forming a
throat with said inner wall, said inner wall having
bleed ports therein forward of said throat, said air
passageway being provided with an end wall having
openings into dump gates;
a free piston valve disposed .at each dump gate for
opening and closing each of said dump gates;
a reference pressure source connected in controlling
relationship to said free piston valves to control the
opening and closing thereof; and
a resilient ring disposed around said openings into
said dump gate to provide seats for said free piston
valves.
2. A supersonic inlet for a jet aircraft engine compris-
ing:
an annular cowling having an outer wall and an inner
wall forming an air passageway;
a centerbody disposed in said cowling and forming a
throat with said inner wall, said inner wall having
bleed ports therein forward of said throat, said air
passageway being provided with an end wall having
openings into dump gates;
a free piston valve disposed at each dump gate for
opening and closing each of said dump gates;
said free piston valve comprising a cup and piston
slidably disposed therein to form a variable volume
chamber, said chamber communicating with a ref-
erence pressure source, said piston engaging said
opening into said dump gate to close same when
said reference pressure is greater than the pressure
at said air bleed port; and
a reference pressure source connected in controlling
relationship to said free piston valves to control the
opening and closing thereof.
3. The structure of claim 2 wherein said bleed ports
comprise an annular slot.
4. The structure of claim 2 wherein each dump gate
includes an outer grill comprising vanes each disposed
at an angle such as to direct air from said openings rear-
ward.
5. The structure of claim 2 wherein said reference
source comprises a conduit connected between each
free piston valve and a respective reference port in said
centerbody, said reference port being axially posi-
tioned between said bleed ports and the normal posi-
tion of the terminal shock wave.
6. The structure of claim 2 and including a spring-
loaded, piston-actuated check valve in said chamber.
7. The structure of claim 2 and further including
pressure regulator means interposed between said ref-
erence pressure source and said free piston valves to
regulate the pressure supplied to said valves whereby
3,799,475
said valves open when the terminal shock wave moves
forward to said bleed ports.
8. The apparatus of claim 2 wherein said piston is of
substantially smaller diameter than said cup and includ-
ing a rolling seal disposed between said piston and said
cup.
9. The structure of claim 8 and including a spring-
loaded, piston-actuated check valve in said chamber.
10. The structure of claim 2 and including isolator
means connected between said reference pressure
source and each free piston valve to inhibit closing of
said valve when the terminal shock is upstream of its
normal position.
11. The structure of claim 10 and including a pneu-
matic capacitor connected between said reference
pressure source and each free piston valve.
12. The structure of claim 10 and including a restric-
tor connected between said reference pressure source
and each of said free piston valves.
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Airflow control system for supersonic inlets

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