荷兰专利NL1021526A Jet pipe ring for an aircraft engine.

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优先权

专利摘要:
A shroud for an aircraft engine exhaust plume, the shroud being formed of a flexible material secured at one end to the exhaust nozzle and selectively extendable downstream with the exhaust plume so as to surround and shroud 5 it, thereby to reduce infrared/radar/noise emissions trom the aircraft engine. 1021526
公开号:NL1021526A
申请号:NL1021526
申请日:2002-09-24
公开日:2016-09-22
发明作者:Giacomo Robert Colosimo Nicholas
申请人:Bae Systems Plc；
IPC主号:

专利说明:

Title: Jet pipe ring for an aircraft engine.
The invention relates to jet pipes for an aircraft engine, and in particular to jet pipes for the exhaust plume of the exhaust nozzle of an aircraft jet engine.
The typical exhaust plume of an aircraft engine makes a major contribution to the infrared image of the aircraft and is also an important source of noise (it is assumed that shear layers within the initial core region of the exhaust plume are the origin of a significant amount of the noise of the jet engine ).
Conventional methods for reducing infrared and / or noise emissions include encasing the exhaust plume, but large, generally cylindrical rigid structures are used for this purpose, or by configuring the rear of the aircraft to shield the exhaust. Both of these measures are undesirable because the structures are bulky, complex and difficult to fit to existing aircraft, and often cause an unacceptable increase in weight and / or an unacceptable increase in fuel consumption of the aircraft, such as aerodynamic flow resistance.
The present invention therefore provides a nozzle ring for the exhaust plume delivered from an aircraft jet nozzle, which nozzle comprises a length of flexible, heat-resistant material attached to the outlet nozzle at one end and selectively deployable around itself extend downstream, substantially parallel to the outlet plume, the deployed jet pipe extending around at least a substantial portion of the circumference of the outlet plume.
Such an arrangement limits the viewing angle to the engine cavity (via the engine exhaust nozzle) and the exhaust plume and keeps them out of sight. Because the shielding material, which preferably reflects and / or absorbs heat to some extent, is at a lower temperature than the engine outlet, this has the effect of reducing the infrared image of the aircraft to be detected. The arrangement is also lighter in weight and smaller than conventional fixed structures and much easier to apply to existing aircraft. Because the nozzle ring is selectively deployable, any adverse effect on flow resistance or properties caused by the deployed nozzle ring need only occur when it is absolutely necessary that the nozzle is deployed. The jet pipe material can also be provided with a radar absorber, to help reduce the radar cross section of the aircraft and the reflection signal from the engine; similarly, the material may be acoustically absorbent and / or reflective, by incorporating suitable additions, or by the shape and configuration, so as to reduce the noise level produced by the engine outlet, the jet ring acting as a sound shield. Finally, the nozzle ring can be formed and / or designed to generate turbulence to promote mixing of the hot exhaust gases with cooler ambient air, thereby advantageously reducing the infrared image of the exhaust plume.
The shielding ring, when deployed, may extend around substantially the entire circumference of the outlet plume and may advantageously be in the form of a tube of material. Such a tube could be deployed by means of a telescopic or extension mechanism, so that the nozzle can be brought out when its infrared / radar / sound shielding qualities are required and can be retracted when these features are not required (given that the deployed nozzle will inevitably increase the flow resistance of the aircraft and that noise reduction is required especially when the aircraft lands, there is usually a synergy in that it is desirable to increase the flow resistance upon landing, so that deploying the nozzle will not only cause the landing noise but will also assist with the landing processes).
Alternatively, there may be a jet pipe deployment mechanism, which mechanism is activated by the "onset" airflow when the aircraft is in flight to deploy the jet pipe ring, the mechanism being adapted to retract the jet pipe ring as the " onset "flow (which is related to the air speed of the aircraft) decreases below a predetermined level. This mechanism can be operated resiliently so that when the flow resistance induced by the deployed jet pipe ring increases (as the air speed of the aircraft increases), it increases the length of the jet pipe ring and as the air speed decreases, the jet pipe ring is retracted; when the aircraft is on the ground, the jet pipe ring would normally be completely withdrawn.
The tubular jet pipe ring can be kept open and in position by means of tubes with open ends of flexible material that are attached to the outer surface of the jet pipe ring and adapted to inflate due to the increasing air flow along it when the aircraft is in the air wherein the inflated tubes with an open end support the deployed jet pipe ring when the aircraft is in the air. Alternatively (or additionally), a rigid or semi-rigid ring can be received at the downstream end of the nozzle ring, which ring is adapted to keep the nozzle ring open and in tubular form when the nozzle is deployed.
Alternatively, the jet pipe ring may comprise an inflatable tube matrix, such as one or more longitudinal "backbone (s)" and a number of ribs attached thereto, adapted to inflate in use to deploy and support the jet pipe ring when the plane is in the air.
The inflatable matrix can be inflated by the air flow past the aircraft in flight or a supply of pressurized gas from a gas cylinder; a pyrotechnic device may also be provided for this purpose.
High-pressure inflatable structures can be extremely stiff when inflated and deployed, which is advantageous to eliminate or at least substantially reduce movement of the deployed jet pipe ring. This restriction serves to reduce air resistance and also reduces the risk of damage to the nozzle ring induced by the jet engine or "onset" flow.
The nozzle ring may comprise a plurality of longitudinal strips of material, with each strip attached to the outlet nozzle at one end. Such an arrangement is more flexible in use, is particularly useful when the aircraft is maneuvering, is easier to repair when a portion of the nozzle ring is damaged and is easier to bring out and retract by an "onset flow" mechanism as described above . The strips are preferably arranged in such a way that they overlap each other in the longitudinal direction in order to reduce the chance of the strips separating and allowing sound and / or infrared to emerge. The overlap also prevents the leaking of hot exhaust gases between adjacent strips; the strips may overlap or there may be concentrically staggered ring strips so that for the escape of exhaust gases it is necessary to follow a winding path between them.
The nozzle can include a piece of material that is attached to and hangs from one edge of the outlet nozzle and extends around at least a lower portion thereof, the flap preferably being shaped so as to extend around at least the lower portion (preferably the lower half, less preferably the lower third part, of the circumference of the outlet plume and shield it and hide it from a viewer on the ground below the outlet nozzle.
Preferably, the length of the nozzle ring, when deployed, is approximately equal to the length over which the initial core region of the outlet plume extends from the outlet nozzle, or approaches at least its maximum length. This also aims to optimize "hiding" while minimizing the induced drag.
The invention also provides an aircraft provided with a jet pipe ring described above.
The invention will now be described by way of example, with reference to the drawings, in which: Figure 1 shows a schematic view of the rear end of an aircraft; Figure 2 is a schematic view of the aircraft of Figure 1, showing the principle of the invention; Figure 3 is a schematic view of a first embodiment of a nozzle ring according to the invention; Figure 3a shows a cross-section of a part of the nozzle ring of Figure 3; Figure 4 is a schematic view of a portion of an automatic deployment mechanism for the nozzle ring of Figure 3; figures 5a and 5b show schematic views of the jet pipe ring of figure 3 in use on an airplane in flight and on the ground respectively; Figures 6a and 6b are schematic views of a deployment mechanism for a second embodiment of a nozzle ring according to the invention, and show the nozzle line in retracted and deployed condition, respectively; Figure 7 is a schematic view of another embodiment of a nozzle ring according to the invention; Figure 8 is a schematic view of a further embodiment of a nozzle ring according to the invention; Figures 9a and 9b show the nozzle ring of Figure 8 in use, in the unfolded and deployed condition, respectively; and Figures 10a and 10b are schematic views of a further embodiment of a nozzle ring according to the invention, in partially and fully deployed states, respectively.
The same reference numerals are used in the figures to indicate the same elements.
Figure 1 shows the rear part of an aircraft 1 with an engine nozzle 3 from which a plume 5 of exhaust gases comes. The outlet plume 5 has a very hot initial core region 7 and the nozzle 3 has an outlet opening 9.
In flight, the initial area 7 makes a significant contribution to the infrared image of an aircraft 1; an observer who has a line of sight through the nozzle outlet 9 into the aircraft engine will also see the heat generated therein and therefore the aircraft engine will produce a very strong infrared signal along this line of sight. It is also assumed that the initial area 7 makes a significant contribution to the noise from the jet engine, which noise is assumed to be caused by the shear layers in the initial area 7.
Figure 2 shows the aircraft 1 provided with a cylindrical nozzle ring 11 with an open end, which is mounted at suitable points at the rear of the aircraft and which surrounds the engine nozzle 3 and a substantial part of the core region 7. The shielding ring 11 holds the nozzle 3 and the core area 7 out of sight and limits the angle through which they and the exit opening 9 can be seen. Because the shielding ring 11 has a temperature that is lower than that of the elements that it keeps out of sight, it has the effect that the infrared radiation to be detected is reduced. The jet pipe ring further shields at least a portion of the core region 7 and, by reflection and / or absorption, reduces the amount of jet engine noise and the infrared emission. Conventional jet rings are bulky, complicated and heavy structures that are difficult to attach to existing aircraft and, once installed, cannot be removed during flight and cannot easily be removed anyway.
Figure 3 shows a nozzle ring 11 'according to the invention formed from a number of strips 13 of fire-resistant, flexible material, each of which is attached at one end to a ring 15, which is attached directly or by some additional structure 17 to the rear end of the aircraft or at the mouthpiece 3. The strips 13 are arranged in two or more concentric and mutually displaced rings (see Figure 3a) so that the strips overlap each other, so that there is no clear path through the jet ring 11 'for any noise, infrared or hot exhaust gas emission, on the contrary, gas that wants to pass from the exhaust plume through the nozzle ring 11 'must follow a curved path.
The strips 13 shown in Figure 3 may simply be attached to the aircraft at one end, or may be retractable, as shown in Figure 4, with a single strip 13 being wound on a spring-loaded roller 19 which serves to to keep the strip 13 rolled up in the absence of any external force. The roller 19 is mounted such that when the aircraft is flying forwards, the "onset" flow of air on the material of the strip 13 causes a compelling frictional effect, whereby the strip 13 is unrolled in the downstream direction, as shown by the arrow in Figure 4. Because the drag force caused by the "onset" flow is proportional to the forward air velocity, the longer the strip rolls over, the longer the air velocity is; this is advantageous because the higher the air velocity, the longer the hot area of the outlet plume to be shielded from observation.
Figures 5a and 5b show, when there is no mechanism as in Figure 4, how the strips 13 of the jet ring 11 'are extended by the "onset" airflow when the aircraft 1 is flying forwards (Figure 5a), as opposed to when there is is not a forward air speed when the aircraft is on the ground or is stationary (Figure 5b). In the first case the strips 13 flow out and extend parallel to the outlet plume 5, while in the second case the strips 13 hang limply downwards. It will be appreciated that in the latter case, the strips hanging down from the upper part of the nozzle ring tend to hang over the outlet nozzle and may be damaged, therefore, a retractable nozzle is generally preferred.
It should be noted that the nozzle ring 11 'can be composed of strips of different or varying widths; there may be a larger number of thinner material strips or a smaller number of wider material strips or a mixture of thick and thin strips around the circumference of the motor nozzle 3. As a last resort, a single strip in the form of a tube or cylinder made of flexible material can hereby arise. With such a device, the material can be damaged by the engine's exhaust gas flow when the aircraft has no forward air velocity, and therefore there is preferably some form of a retraction mechanism, either similar to that of Figure 4, or as shown in Figures 6a and 6b.
Figures 6a and 6b show a tubular jet pipe ring 11 "that is folded (Figure 6a) prior to a forward flight and can be extended, as in Figure 6b, through a telescope mechanism 21, when the jet pipe ring 11" is needed. The telescopic mechanism comprises one or more separate telescopic arms 21 through which the nozzle ring 11 "can be selectively deployed or retracted. Other mechanisms for unfolding and withdrawing the nozzle ring will be obvious to those skilled in the art. The tubular nozzle pipe 11" becomes at least partially stopped by the flow therethrough of the exhaust plume and by the use of a rigid or semi-rigid ring (not shown) integral with or attached to the downstream end of the nozzle ring 11 ". Additionally or otherwise, the nozzle can be kept open by the "onset" flow of ambient air, which can be directed inside the nozzle ring (to form a boundary layer between the material of the nozzle and the outlet plume) and / or through tubes with open ends inside and / or outside the shield ring For example, as shown in Figure 7, a number of tubes 23 with an open end from one or other flexible material is provided around the outer circumference of the jet pipe ring 11 ", which tubes are designed to be inflated by keeping the air flow therethrough and thereby the jet pipe ring 11" semi-rigid, stabilizing and reducing the air resistance and the range of movement of reduce the nozzle ring, thereby keeping it away from possible damage caused by the hot exhaust plume. The tubes 23 have a large upstream opening and a smaller downstream opening, which causes the air passing through the tube to come under pressure and thus keep the tubes 23 semi-rigid.
Figure 8 shows another jet pipe ring 11 "'comprising a longitudinally directed portion of a flexible material cylinder extending only partially around the circumference of the engine exhaust nozzle 3; this is usually the lower portion of the circumference of the aircraft when in a horizontal flight, assuming that it is probable that some observation of the infrared and / or noise emissions from the aircraft from below will occur from the ground. In this case, the jet pipe ring 11 "is permanent deployed so that in a forward flight the "onset" flow of air keeps the nozzle ring 11 "'unfolded in its position (Figure 9b), while the nozzle ring 11"' sinks down when the aircraft 1 is not in a forward flight (as in Figure 9a); the partial circumference of the jet pipe ring 11 '"prevents the jet pipe material from being damaged by the hot exhaust plume when the aircraft is not flying forwards, the" onset "airflow causing the jet pipe ring 11" to extend. The jet pipe ring is preferably about half or three quarters of a cylinder, although certain aircraft exhaust nozzles may be sufficiently shielded by a jet pipe ring of only one third or one quarter of the total cylinder. Also, the edges 25 of the nozzle ring 11 '"may be straight, as shown whether they may extend or be curved depending on the degree of shielding required, and / or the design and / or configuration of the rear of the aircraft 1.
The flexible material from which the nozzle is made is fire-resistant and absorbs and / or reflects thermal radiation. Preferably, it also absorbs acoustic energy and may be shaped and / or configured to more effectively shield the sound from the jet engine. The material may include additives that support the absorption of thermal, radar and / or acoustic emissions, such as foam structures and the like that are known per se.
Other modifications will be apparent to those skilled in the art. For example, the nozzle ring can be held open by resilient members, such as semi-rigid elements or inflatable tubes.
A matrix of inflatable tubes can be provided to deploy and keep the nozzles open. The inflatable tubes may be in the form of one or two longitudinal "spine (s)" 31 with a plurality of "ribs" 33 attached thereto, as shown in Figures 10a and 10b. The inflatable support matrix can be inflated to deploy the jet pipe ring 11 "" by diverting the air flow past the aircraft, as described above, or there may be provided a supply of compressed gas that can be used to inflate the matrix . The compressed gas can be supplied from a cylinder, or from a pyrotechnic device, as is known in the field of rapidly inflatable structures. On the other hand, the matrix can be inflated by a "settling" foam, of the type comprising a liquid with trapped gas bubbles therein, which liquid "sets" in a solid state in a relatively short period of time, for example through a core of heat. The "settled" foam structure is rigid and functions as a thermal absorber for the heat from the jet engine exhaust plume; and may also be provided with radar-absorbing particles, which would improve the shielding of the aircraft.
A number of rigid or semi-rigid rods may be located within the jet ring ring, between the jet ring ring and the outlet plume, to prevent the jet ring ring from collapsing inwards and coming into contact with the jet engine. For this purpose a resilient helical element can also be provided, which can also serve to deploy the nozzle ring. On the other hand, there may be provided a single annular inflatable sleeve which surrounds or is located within the nozzle ring to deploy and support the nozzle ring. In another embodiment, a rail structure may be provided that circles around the outlet nozzle with the nozzle being held in an adjacent compartment and adapted to deploy when it is released from the compartment to run along the rail, such as a curtain on a curtain rail . On the other hand, the nozzle ring can be received in an annular compartment that surrounds the outlet nozzle or a little upstream thereof, with a release mechanism whereby the nozzle is deployed. Advantageously, the release mechanism can be arranged to hold both one end of the nozzle ring around the outlet nozzle and also to allow the "onset" air to flow between the attached end of the nozzle ring and the frame of the aircraft / outlet nozzle, to blow the nozzle and keep it open. The release mechanism is selectively operable in the same manner as, for example, a brake parachute, so that the nozzle can be deployed when it is needed. A further mechanism may be provided to throw the jet ring instead of retracting it.

权利要求:
Claims (15)
[1]
What is claimed is: 1. A jet pipe ring for the exhaust plume of a jet engine of an aircraft, which exhaust plume is delivered by an exhaust nozzle, characterized in that the jet pipe ring comprises a length of flexible, heat-resistant material which is attached to the exhaust nozzle at one end and is selectively deployable to extend downstream substantially parallel to the outlet plume, wherein the deployed jet pipe extends around at least a substantial portion of the circumference of the outlet plume.
[2]
A jet pipe ring according to claim 1, characterized in that the material is acoustically and / or infrared reflecting and / or absorbing and / or radar absorbing.
[3]
A jet pipe ring according to claim 1 or 2, characterized in that the jet pipe ring extends around substantially the entire circumference of the outlet plume.
[4]
The jet pipe ring according to claim 3, characterized in that the jet pipe ring is in the form of a tube of material.
[5]
A jet pipe ring according to claim 4, characterized by a deployment mechanism for deploying the jet pipe ring activated by the "onset" airflow when the aircraft is in flight, which mechanism is arranged to retract the jet pipe ring when the "onset" flow decreases below a predetermined level.
[6]
A jet pipe ring according to claim 4 or 5, characterized in that the jet pipe ring comprises one or more inflatable elements which are adapted to deploy the jet pipe ring when inflated and to support the deployed jet pipe ring when the aircraft is in flight.
[7]
A jet pipe ring according to claim 4 or 5, characterized by a matrix of inflatable tubes adapted to inflate in use so as to deploy and support the jet pipe ring when the aircraft is in flight.
[8]
A jet pipe ring according to claim 7, characterized in that the matrix comprises one or more inflatable longitudinal "spine (s)" and a number of inflatable "ribs" attached thereto.
[9]
9. Jet pipe ring according to claim 6, 7 or 8, characterized in that the inflatable elements are tubes with an open end made of flexible material, which are mounted on the outer surface of the jet pipe ring and are adapted to inflate as a result of the " onset "airflow past it, when the aircraft is in flight.
[10]
A jet pipe ring according to claim 6, 7 or 8, characterized in that a supply of compressed gas is provided to inflate the elements.
[11]
The jet pipe ring of claim one of claims 4 to 10, characterized by a rigid or semi-rigid ring on the downstream end of the jet ring ring adapted to keep the jet ring ring open and in tubular form when the jet pipe ring is deployed.
[12]
A jet pipe ring as claimed in claim 1, 2 or 3, characterized in that the jet pipe ring comprises a number of longitudinally arranged strips of material, each strip being attached to the outlet nozzle at one end.
[13]
A jet pipe ring according to claim 9, characterized by a deployment mechanism that is activated by the "onset" airflow when the aircraft is in flight to deploy the jet pipe ring along the exhaust plume, which mechanism is adapted to retract the jet pipe ring when the "onset" current decreases.
[14]
A jet pipe ring according to claim 1, 2 or 3, characterized by a single piece of material attached to one edge around at least a lower portion of the outlet nozzle, said piece being shaped such that it extends around at least the part of the circumference of the exhaust plume and shield it from an observer on the ground.
[15]
A jet pipe ring according to any one of the preceding claims, characterized in that the length of the jet pipe ring, when deployed, approaches at least the maximum length over which the initial core region of the outlet plume extends from the outlet nozzle.

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同族专利:

公开号 | 公开日

GB2407133B|2006-04-19|

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FR2865455A1|2005-07-29|

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FR2865455B1|2008-05-30|

ES2245148A1|2005-12-16|

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ES2245148B1|2007-02-01|

ITWX20020017A1|2003-03-26|

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GB2407133A|2005-04-20|

AU2002300521A1|2005-09-08|

AU2002300521B2|2007-05-17|

SE526277C2|2005-08-09|

DE10242393B4|2008-01-31|

GB0222198D0|2005-02-02|

引用文献:

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DE4433462C1|1994-09-20|1995-12-07|Daimler Benz Aerospace Ag|Radar jammer for protection of aircraft propulsion units|RU2518694C1|2012-12-29|2014-06-10|Федеральное государственное унитарное предприятие "Крыловский государственный научный центр"|Device to reduce intensity of ir-radiation of gas flow and external surface of vessel stack to reduce their thermal visibility|

US8528312B1|2013-01-08|2013-09-10|Ali A. A. J. Shammoh|Turbojet engine inlet and exhaust covers|

US9975633B1|2016-05-10|2018-05-22|Northrop Grumman Systems Corporation|Collapsible ducted fan unmanned aerial system|

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CN106593696A|2016-12-21|2017-04-26|南京航空航天大学|Symmetrical and asymmetrical exhausting system capable of improving afterbody flow field, and method thereof|

法律状态:
2018-05-09| MM| Lapsed because of non-payment of the annual fee|Effective date: 20171001 |

优先权:

申请号 | 申请日 | 专利标题

GB0122987A|GB0122987D0|2001-09-25|2001-09-25|Aircraft engine exhaust shroud|

GB0200180A|GB0200180D0|2002-01-04|2002-01-04|Aircraft engine exhaust shroud|

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