FR2677078A1 - Air intake for hypersonic engine, and hypersonic flying machine - Google Patents

Abstract

A hypersonic air intake with three-dimensional ramp (10) includes an upper element (16) with a caret-shaped lower surface part (22) producing a wedge-shaped two-dimensional flow under this surface part. The air intake also includes a lower element (18) which includes two inverted and transposed half-caret shaped upper surface parts (26, 28) producing a wedge-shaped two-dimensional flow above these upper surface parts. A rear part connects the upper and lower elements and includes an orifice defining the throat (mouth) of the air intake, which at least partially receives the two-dimensional flows.

Description

AIR INTAKE FOR A HYPERSONIC MOTOR AND
HYPERSONIC FLYING MACHINE
The present invention relates generally to flying machines, and it relates more particularly to an air intake for a hypersonic flying engine engine.

 At hypersonic Mach numbers (i.e. larger than Mach 5), a flying craft equipped with a motor that sucks in air requires an air inlet having an air capture region of large dimensions. In addition, the design of a hypersonic flying engine requires air intake surfaces to have a three-dimensional sweep structure to reduce aerodynamic drag and friction heating. Three-dimensional sweeping engine air intake structures can produce non-planar flow components requiring a complex and possibly impractical analysis of a three-dimensional air flow path. in the case of supersonic, non-hypersonic motors, having ramped air inlet surfaces which produce planar flow components, allowing a much easier analysis of a two-dimensional air flow path. In addition, a two-dimensional flow makes it easier to perform direct testing of engine components (which means testing an engine component by reproducing its input conditions with a certain device, without having to use the upstream engine components to produce such conditions entry conditions), such as testing a motor without its large air intake by reproducing the two-dimensional air flow conditions calculated at the engine throat .Finally, a hypersonic motor structure can exert on the flying machine a pitching torque which would require constant compensation, for example by a control surface producing a drag.

 In the description of the invention, the expression "caret-shaped surface" will be used. In the context of the invention, a "caret-shaped surface" is defined as the surface of an isosceles triangle which has been folded along its height relative to the base, to form two right triangles which are images l from each other in a mirror and which meet along the height forming a negative lateral dihedral angle. To help visualize this caret-shaped surface, you can cut an isosceles triangle from a piece of rigid paper and fold the triangle along the height, so that two right triangles which are images of each other in a mirror, are mutually superposed. (The operations carried out until now are identical to the initial operations to manufacture certain paper airplanes.) If the folded isosceles triangle is placed on the surface of a table, so that the support sides of the isosceles triangle rest on the table surface, the two parts consisting of right triangles will form a negative lateral dihedral angle at the level of the height of the isosceles triangle. The lower (inner) surface of the folded isosceles triangle is a caret-shaped surface. The angle between the height (the fold line) and the air flow is the angle of attack of the shaped surface. caret.

 For specific combinations of hypersonic speed and angle of attack (hereinafter called "predetermined operating conditions"), which those skilled in the art can determine, the caret-shaped surface defined here -above produces a plane shock wave in the plane of its leading edges (the plane containing the support sides of the folded isosceles triangle, which is also the plane of the table surface), which leads to pressure uniform between the shock wave and the caret-shaped surface (the bottom surface of the folded isosceles triangle), equal to the pressure behind the shock wave in a two-dimensional wedge-shaped flow. A good approximation of a two-dimensional wedge-shaped flow will be obtained for conditions deviating from the nominal hypersonic velocity and angle of attack.

The caret-shaped surface of the invention is identical to the lower surface of the caret wing which is described in the technical literature. Caret wings are described in an article by K. Kipke entitled "Experimental Investigations of Wave Riders in the Mach
Number Range from 8 to 15 "published in AGARD Hypersonic
Boundary Layers and Flow Fields (May 1968).

 An object of the invention is to provide an air intake for a flying engine engine having a large air capture region.

 Another object of the invention is to provide an air inlet for a hypersonic flying engine engine which has a three-dimensional swept structure but which nevertheless provides a two-dimensional flow.

 A further object of the invention is to provide a hypersonic flying engine which produces a pitch torque of zero general value.

 A further object of the invention is to provide a hypersonic flying machine comprising a motor which makes it possible to exert a pitch control on the machine.

 In a first embodiment, the air intake of the engine of a flying vehicle of the invention comprises a first element, a second element and a rear part.

Each of the first and second elements comprises at least one surface part which is generally in the form of a caret, and these elements are arranged face to face on either side of a capture region which partially contains the flows. two-dimensional wedge-shaped produced by such caret-shaped surface parts. The rear part brings together the first and second elements and it has an orifice which forms the neck of the engine air intake.

 In a second embodiment, the air inlet of the hypersonic flying engine motor of the invention comprises an upper element, a lower element and a rear part. The upper member has a lower surface portion which is generally in the form of a caret. The lower element has two upper surface parts which generally have the shape of a half-caret and which are inverted and transposed. The rear part connects the upper and lower elements and has an orifice forming the neck of the engine air intake.

 In a third embodiment, the hypersonic flying engine of the invention comprises the air inlet of the second embodiment described above, a combustion chamber, fuel injectors and an ejection nozzle. The fuel injectors are placed in the combustion chamber, and the combustion chamber is connected in series to the rear part of the air inlet. The exhaust nozzle is connected in series to the combustion chamber and has upper and lower segments of generally symmetrical shape.

 In a fourth embodiment, the hypersonic flying machine of the invention comprises the engine of the third embodiment described above, and two arrowed wings attached to the lower element of the engine air intake, while each of the upper and lower segments of the ejection nozzle has a rear flap for pitch control, and each wing has a mechanism for yaw and roll control.

 The invention provides several advantages. The caret and half-caret air inlet surfaces provide an air inlet for a hypersonic engine with a three-dimensional arrow structure and capable of capturing a large volume of air, which produces a two-dimensional flow in the form of corner. This makes it easier to analyze a two-dimensional air flow path and makes it easier to test engine components by direct link. The symmetrical upper and lower segments of the exhaust nozzle produce a pitch torque of zero general value. The rear flaps on the upper and lower segments of the exhaust nozzle provide a motor capable of exercising pitch control.

The invention will be better understood on reading the following description of embodiments, given by way of nonlimiting examples. The following description refers to the accompanying drawings in which
Figure 1 is a perspective view of the hypersonic flying machine comprising its engine air inlet;
Figure 2 is a side section of the supersonic motor; and
Figure 3 is a front elevational view, in perspective, of the hypersonic flying machine.

 Figures 1 to 3 illustrate the present invention, implemented in the form of an engine air inlet 10, a hypersonic engine 12 and a flying machine 14. The engine air inlet 10 of a flying machine is designed for hypersonic operation and it comprises a first element or upper element, 16, a second element or lower element 18 (preferably having, but not necessarily, two upper surface portions 26 and 28 which will be described later), and a rear part 20.

The upper element 16 of the air intake comprises a lower surface part having a general shape in ca ret, 22, and a profiled upper surface 24. The lower caret-shaped surface part 22 has the shape of the lower surface of a caret wing. As is known to those skilled in the art, the bottom three-dimensional jib surface of a caret wing produces a two-dimensional wedge-shaped flow below this bottom surface, under predetermined operating conditions of angle hypersonic attack and speed (which is typically chosen for the cruising speed of the craft). The upper surface 24 of the air intake 10 of the engine also forms part of the fuselage of the craft , and the passenger compartment (for a manned vehicle) and at least part of a hold containing the payload, can be placed between the upper surface 24 and the lower surface portion in the form of a caret 22 of the entry engine air 10.

 The lower element 18 of the air intake has two upper surface parts having a general half-caret shape, inverted and transposed, 26 and 28, which are defined as follows: invert (i.e. - say to turn over) the lower surface of a caret wing to obtain a higher surface in the form of a caret, then cut this surface longitudinally in two halves to produce two upper surfaces in the form of a demicaret (mutually symmetrical), and then transpose the two Top half-caret surfaces (i.e. swap their positions without rotation). The top half-caret surface portions 26 and 28, having a three-dimensional arrow, will produce a two-dimensional wedge-shaped flow at the -above these surface parts, under predetermined operating conditions of angle of attack and hypersonic speed (which are chosen equal to the angle of attack and the speed h chosen for the design of the caret-shaped lower surface part 22 of the upper element 16 of the air intake), as those skilled in the art will note. caret-shaped lower surface part 22 and the half-caret-shaped upper surface parts 26 and 28 are arranged and oriented so as to also compress their respective two-dimensional flows at the neck 30, at the predetermined hypersonic speed. It is preferable that each upper surface part in the form of a half-caret 26 and 28 of the lower element 18 of the air intake is created from a half cut in the longitudinal direction, inverted and transposed, from the caret-shaped lower surface part 22 of the upper element 16 of the air inlet. The upper half-shaped surface parts 26 and 28 are joined on the inner side to correspondingly profiled lower surface parts , 32 and 34, of the lower element 18 of the air intake, so that these lower surface parts also constitute a part of the fuselage of the craft, and so that at least part of the train landing can be placed between these upper and lower surface portions. The upper surface parts 26 and 28 and the lower surface parts 32 and 34 are joined on the outside to corresponding upright ramp parts, 36 and 38, of generally vertical orientation, which help to limit the amount of air d input which is lost by lateral leakage during operation outside nominal conditions, at low Mach numbers.

 The rear part 20 of the air inlet provides the connection between the upper 16 and lower 18 elements of the air inlet, and it has an orifice which defines the neck 30 of the air inlet 10 of the engine . The neck 30 receives at least part of the two-dimensional wedge-shaped flows which are produced by the upper 16 and lower 18 elements of the air inlet. It can be seen that the upper 16 and lower 18 elements of the air inlet are generally disposed face to face on either side of an air capture region 40 which is large relative to the size vehicle 40. A high area capture area is required at high speeds. At lower speeds, at least a fraction of the unnecessary portion of the intake air naturally leaks through the open side and lower parts of the air intake of the engine, which reduces the need for an engine having a geometrical configuration of variable air intake.

 To provide the increased compression that is required at high speeds, the rear portion 20 of the engine air inlet 10 also includes an upper transition ramp 42 and two lower transition ramps 44 and 46. The upper transition ramp 42 extends down from the caret-shaped lower surface part 22 of the upper element 16 of the air intake, and it ends on the rear side at the level of the neck 30. The transition ramps lower 44 and 46 (which can be combined together to form a single ramp) extend from an upper surface part in the form of a corresponding half-caret, 26 and 28, of the lower element 18 of the 'air intake, and they end on the rear side at the neck 30.

As one skilled in the art will appreciate, the transition ramps guide the two-dimensional flow from the corresponding caret or semi-caret surface, without affecting its two-dimensional nature. In addition to the fact that the transition ramps increase the compression, they also make it possible to give a rectangular shape to the neck 30 of the air intake, which simplifies the analysis and the test. A geometric configuration of rectangular neck also ensures an efficient transition with the combustion chamber part 48 of the engine, located downstream. It is preferable that the transition ramps are mobile, to adjust the height of the rectangular-shaped neck. The fact of having a rectangular-shaped neck of variable area allows adjustment to be made for different compression ratios that the engine at different speeds during flight, such as at an increasing speed from Mach 5 to Mach 25 or 30. A rectangular neck of variable area also allows the use of a variable geometric configuration in the combustion chamber part of the engine, as it might be desirable for operation over a wide range of flight Mach numbers.

 The hypersonic engine 12 is preferably a ramjet, a hypersonic combustion ramjet, a hybrid or combined cycle engine, or a similar engine, and it comprises the air inlet 10 described above, a combustion chamber 48 connected in series. at the rear part 20 of the air inlet, a set of fuel injectors 50 placed in the combustion chamber 48, and an ejection nozzle 52 connected in series to the combustion chamber 48. The nozzle ejection 52 comprises symmetrical upper 54 and lower 56 segments which jointly produce a pitch torque of zero general value. The rear part 20 of the air intake 10 of the engine preferably has mutually spaced ribs 58, having an arrow profile. These ribs 58 provide structural support and they are placed in front of the neck 30, near this last and extend in the direction of its width. Additional fuel injectors (not shown) are placed in the rear part 20 of the air inlet, such as for example on the walls of the ribs 58 and / or in their rear regions facing backwards.

 The hypersonic flying machine 14 comprises the engine 12 described above and two arrow wings 60 and 62 which are fixed to the lower element 18 of the air inlet. The wings 60 and 62 include control means for maneuvering the machine in yaw and roll. These means preferably include inclined vertical fins 64 and 66. Other means of this type include parts of roll control flap in the wings plus vertical fins with parts of yaw control flaps, jet jets , etc., as is known to those skilled in the art. The pitch or depth control of the machine is provided by rear flaps 68 and 70 which are fixed to the upper 54 and lower 56 segments of the ejection nozzle. At hypersonic speeds, the pitch control is achieved by turn inward a rear flap 68 or 70 to bring it into the ejection region 72 of the nozzle, since the air pressure may be insufficient for controlling the machine by the rotation of a rear flap towards the outside of the exhaust nozzle, in particular if the outside region is in the "shadow" of the vehicle with respect to the flow of free air. Since a hypersonic machine requires large amounts of fuel (as well as air), fuel tanks 74 having a shape integrated into the structure are arranged at least partially inside the ejection nozzle 52 .

 It is preferable that the hypersonic flying machine 14 take off from a runway while being propelled by take-off flares 76 mounted on the sides of the ejection nozzle 52. When a speed sufficient for the operation of a ramjet or d 'A hypersonic combustion ramjet is reached, the rockets 76 are deactivated or dropped, and the engine 12 described above takes over to propel the flying machine 14 to hypersonic speeds. Other take-off means can be envisaged, comprising mounting the craft on the back of a large supersonic aircraft of the conventional type, or incorporating one or more turbojet engines operating in a hybrid cycle into the craft. or combined with the engine of the invention, as is known to those skilled in the art. When an orbital operation of the flying object 14 is desired, the rockets 76 can be re-ignited, if necessary, to contribute to obtaining the final orbital speed.

 Typical design parameters, which have been simulated on a computer, include a predetermined hypersonic speed of Mach 25, an air intake contraction (area) ratio of 30 to 1, angles of transition ramps from 5 to 11 degrees, and a deflection angle of the leading edge of the air inlet of 77 degrees.

 The foregoing description of several preferred embodiments of the invention has been presented for the purpose of illustration. It is not intended to be exhaustive or to limit the invention to the precise form which has been described, and numerous changes and modifications are obviously possible on the basis of the preceding description. It should be noted that the terms "upper" and "lower" are terms which are used for convenience in describing the elements of the air intake 10 of the engine. For example, it is clear that the air inlet 10 of the engine can be oriented at any angle chosen in advance, in relation to the longitudinal axis of the machine, relative to the rest of the hypersonic flying device 14. In a preferred embodiment of the hypersonic flying device 14, the terms "upper" and "lower" describe the elements of the air intake 10 of the engine when the hypersonic flying device 14 is in horizontal flight.

Claims (10)

 1. Air intake for a flying engine, characterized in that it comprises: (a) a first element (16) having at least one surface part which has a generally caret shape (22), to produce a first flow which is generally two-dimensional and wedge-shaped; (b) a second element (18) having at least a surface portion which is partially of generally caret shape (26, 28), for producing a second flow which is generally two-dimensional and wedge-shaped, the first and second elements (16, 18) being generally arranged face to face on either side of a capture region (40) which at least partially contains the first and second two-dimensional wedge-shaped flows; and (c) a rear part (20) having an orifice defining a neck (30) of the engine air intake and joining the first and second elements (16, 18), so that this neck (30) receives at least part of the first and second two-dimensional wedge-shaped flows.  2. Air inlet for a hypersonic flying engine engine, characterized in that it comprises: (a) an upper element (16) having a lower surface portion generally having a caret shape (22), to produce a first flow which is generally two-dimensional and wedge-shaped, below this lower surface portion (22); (b) a lower element (18) comprising two upper surface parts having a generally half-caret shape, inverted and transposed (26, 28), to produce a second flow of generally two-dimensional and wedge-shaped shape, above the upper surface portions (26, 28); and (c) a rear portion (20) connecting together the upper and lower elements (16, 18) and having an orifice which defines a neck (30) of the engine air intake.  3. Engine air inlet according to claim 2, characterized in that the bottom surface part in the form of a caret (22) and the upper surface parts in the form of a half-caret (26, 28) are arranged and oriented. so that the first and second two-dimensional wedge-shaped flows are compressed generally equal to the level of the neck (30).  4. Engine air inlet according to claim 3, characterized in that each upper surface part in the form of a half-caret (26, 28) is defined by a half cut in the longitudinal direction, inverted and transposed, of the part of caret-shaped lower surface (22).  5. Engine air inlet according to claim 4, characterized in that the rear part (20) also comprises an upper transition ramp (42) which descends from the bottom surface part in the form of a caret (22) and ends on the rear side at the neck (30), and a lower transition ramp (46) which rises from each of the upper surface parts in the form of a half-caret (26, 28) and ends from the rear side at the neck (30).  6. Engine air inlet according to claim 3, characterized in that the neck (30) has a generally rectangular shape.  7. Engine air intake according to claim 6, characterized in that the upper and lower transition ramps (42, 46) are movable to adjust the height of the rectangular neck (30).  8. Engine for a hypersonic flying machine, characterized in that it comprises: (a) an air inlet (10) comprising: (1) an upper element (16) having a lower surface part which has a general shape in caret (22), to produce a first flow of generally two-dimensional and wedge shape, below the lower surface part, (2) a lower element (18) comprising two upper surface parts which have a general shape in half-caret, inverted and transposed (26, 28), to produce a second generally two-dimensional and wedge-shaped flow, above the upper surface parts (26, 28), and (3) a rear part (20) which connects the upper and lower elements (16, 18) together and which comprises an orifice defining a neck (30) of the engine air intake; (b) a combustion chamber (48) connected in series with the rear part (20) of the air inlet (10); (c) a set of fuel injectors (50) disposed in the combustion chamber (48); and (d) an ejection nozzle (52) connected in series to the combustion chamber (48) and comprising upper and lower segments (54, 55), of generally symmetrical shape, which jointly produce a pitching torque of value general null.  9. Hypersonic flying machine, characterized in that it comprises: (a) a motor (12) comprising: (1) an air inlet (10) comprising an upper element (16) having a lower surface portion which has a general caret shape (22), for producing a first flow of generally two-dimensional and wedge shape, below the lower surface part (22), a lower element (18) comprising two upper surface parts of general shape in half-caret, inverted and transposed (26, 28), to produce a second flow of generally two-dimensional and wedge-shaped shape, above the upper surface parts (26, 28), and a rear part (20) which connects the upper and lower elements (16, 18) together and which comprises an orifice defining a neck (30) of the engine air intake; (2) a combustion chamber (48) connected in series with the rear part (20) of the air inlet (10); (3) a set of fuel injectors (50) disposed in the combustion chamber (48); and (4) an ejection nozzle (52) connected in series to the combustion chamber (48) and comprising upper and lower segments (54, 56) of generally symmetrical shape, which jointly produce a pitch torque of general value zero, each of these upper and lower segments (54, 56) comprising a rear flap (68, 70) for controlling the depth or pitch; and (b) two arrow wings (60, 62) fixed to the lower element (18) of the air intake (10) of the engine, these wings comprising means (64, 66) for yaw control and roll.  10. Supersonic flying machine according to claim 9, characterized in that it further comprises: (c) a fuel tank conforming to the structure (74) which is disposed at least partially in the ejection nozzle (52).