GB2485583A

GB2485583A - Aircraft ground run-up enclosure

Info

Publication number: GB2485583A
Application number: GB201019634A
Authority: GB
Inventors: Alexander Fraser
Original assignee: IND ACOUSTICS Co Ltd
Current assignee: IND ACOUSTICS Co Ltd
Priority date: 2010-11-19
Filing date: 2010-11-19
Publication date: 2012-05-23
Also published as: GB201019634D0

Abstract

A rear wall 10 of an aircraft ground run-up enclosure 40 comprising an â Sâ shaped inwardly facing surface 12 which forms an angle of between 30 degrees and 80 degrees to the ground. Towards a rear of the enclosure are transitions 30 and 32 which form a concave structure between side walls 20 and rear wall 10. Air flow from either side of the enclosure 40 is directed through apertures 22 and entrained along an inside of the side walls 20 towards the rear wall 10 of the enclosure 40. The enclosure is scaleable in height to accommodate different type aircraft.

Description

A ground run-up enclosure The present invention relates to a ground run-up enclosure for aircraft which comprises a wall or walls on substantially three sides that in use partially surround an aircraft. The present invention can also be used with a moveable wall on a fcurth side of the enclosure.

Aircraft must be regularly tested to ensure they are safe to fly. One aspect of aircraft testing involves running the aircraft's engines at or near full power whilst the aircraft is on the ground. Whilst an aircraft is static on the ground during these tests, high bypass turbofan jet engines are sensitive to side winds, gusts and abrupt changes in air pressure. Airports are also often located near human populations and the noise generated by aircraft engines being tested can be disruptive.

Previously proposed facilities have provided a simple enclosure, closed on three or four sides by solid walls.

The orientation of the enclosure can be selected If there is a prevailing wind in the place where the engine testing is to take place. if the wind comes from a different direction the facility can have reduced operational availability and under certain wind conditions can be rendered completely unavailable for engine testing.

A simple wall can reduce the effect of side winds but often insufficiently to enable aircraft engine testing.

Disruptive air flows can enter the testing facility from over the top or around the walls. Additionally, a tall wind can cause the engine exhaust to be re-circulated and re-ingested into the engines during testing. Both of these effects can cause engine surges and stalls.

US Patent 6,016,888 (Lynn) proposes enhancements to the side walls of a ground run-up enclosure by providing horizontal vents in the side walls, rolled topped side walls and sloped front side walls.

These features have demonstrated aerodynamic improvements compared with a basic three sided facility but are aimed at slowing the approach air of the cross wind down and reducing vortexes that would be generated by a blunt edged structure. The features of Lynn do not target the primary direction of airflow through the facility and are likely to have no effect upon the generation of vortexes and reclrculation at the rear of the facility where the rear and side walls join. The sloping side wall entry reduces the potential acoustic benefit.

It is therefore an aim of the present invention to provide a facility for testing aircraft engines which overcomes some of the existing problems.

According to a first aspect of the present invention is directed to a rear wall for a ground run-up enclosure comprising an inwardly facing surface which forms an angle of between 30 degrees and 80 degrees to the ground.

The inwardly facing surface of the rear wall may be substantially planar.

The inwardly facing surface of the rear wall may be at least partially concave.

The inwardly facing surface of the rear wall may be substantially "S" shaped.

The rear wall may have a top portion which has a convex inwardly facing surface and a concave outwardly facing surface.

The rear wall may be scaleable in height dependent on the type of aircraft to be tested.

The rear wall may be between 12 and 17 metres in height.

The rear wall directs the engine exhaust out of the enclosure in such a way as to maintain a smooth flow of air within the enclosure so as to minimise flow disruptions which could cause engine surges or stalls.

A second aspect of the present invention is directed to a side wall for a ground run-up enclosure comprising a plurality of vertical elongate apertures within the side wall.

The side wall may comprise at least three vertical elongate apertures within the side wall.

The side wall may comprise between three and seven vertical elongate apertures within the side wall.

Between 10 per cent and 40 per cent of the length of the side wall may comprise vertical elongate apertures.

The apertures may be located substantially within the front half of the side wall of the ground run-up facility.

The location of the apertures may vary dependent on the type of aircraft to be tested.

At least one aperture may be acoustically treated.

At least one aperture may be angled with respect to the side wall so that the portion of the aperture at the outside of the wall is nearer to the rear of the ground run-up facility than the portion of the aperture at the inside of the wall.

At least one aperture may be angled at between thirty and sixty degrees to the side wall.

At least one aperture may be equipped with acoustic silencers constructed utilising a perforate steel face sheet with an acoustic medium behind it.

The apertures in the side wall allow some air to flow into the enclosure from the side. The apertures change the cross wind direction in such a way as to cause the air flow to be entrained along the length of the side wall thereby reducing the formation of a vortex in the space between the side wall and the engine under test.

The prevention of turbulence at the top of the side wall creates a more suitable environment within the enclosure for testing aircraft engines.

Vertical apertures entrain the air flow caused by a cross wind horizontally along the side wall, substantially improving the conditions within the enclosure.

A third aspect of the present invention is directed to a ground run-up enclosure comprising a transition between at least one side wall and the rear wall to form a substantially concave configuration.

The transition may comprise at least one planar surface.

The transition may comprise at least two discrete changes in the same direction in angle between the side wall and the rear wall.

The transition may comprise an at least partially curved surface.

The transition aids the smooth flow of air within the enclosure, helping to create a more suitable environment within the enclosure for testing aircraft engines.

A fourth aspect of the present Invention is directed to a ground run-up enclosure in which a combination of any of the features mentioned above can be combined in a single enclosure to produce a facility which creates a suitable environment for the ground testing of aircraft in wind conditions which would have rendered previous enclosures inoperable.

A preferred embodiment of each of the aspects of the present invention will now be described in detail with reference to the drawings, wherein: Figure 1 shows in cross-section an embodiment of the rear wall of the present invention; Figure 2 shows a side wall according to the prior art; Figure 3 shows a side wall according to the present invention.

Figure 4 shows a side wall and rear wall configuration

according to the prior art;

Figure 5 shows a side wall and rear wall configuration according to an embodiment of the present invention; and Figure shows an embodiment of the ground run-up facility according to the present invention.

Figure 1 shows a rear wall 10 which has an inwardly facing surface 12 and an outwardly facing surface 14.

The inwardly facing surface 12 has a lower portion 12a which is concave. An upper portion 12b of the inwardly facing surface 12 is convex. The inwardly facing surface 12 as a whole is substantially "S" shaped. An upper portion 14b of the outwardly facing surface is concave.

The shape of the rear wall 10 as shown in Figure 1 is designed so that air flowing from an engine (not shown) towards the inwardly facing surface 12 is directed upwards and retains a horizontal velocity. Air which might be flowing towards the outwardly facing surface 14 is directed upwards and has its horizontal velocity altered by the curvature of the upper portion 14b of the outwardly facing surface 14 so that it complements the air flow from the engine (not shown) as shown by the air flow direction arrows. This configuration reduces the confusion of air which occurs in the case of a vertical rear wall or rear wall of constant cross-section.

Figure 2 shows a side wall 20 according to the prior art.

The side wall 20 has no apertures. This causes the air flow which is shown by the direction arrows. Air flowing from outside the side wall 20 into the ground run-up enclosure meets th.e air flow generated by the engine (not shown) and is confused. I0

Figure 3 shows a side wall 20 according to the present invention. The apertures 22 formed within the side wall are angled towards the rear of the ground run-up enclosure. The apertures 22 direct air which flows from the outside towards the side wall 20 so that it is entrained along the inside of the side wall 20. This reduces the confusion of the air as shown by the direction arrows.

Figure 4 shows a side wall 20 and a rear wall 10 according to the prior art. The side wall 20 and rear wall 10 form a right angle between them. The right angle causes air flowing along the side wall 20 towards the rear wall 10 to become confused as shown by the direction arrows.

-10 -Figure 5 shows a side wall 20 and a rear wall 10 with transition sections 30 and 32 between the side wall 20 and the rear wall 10. The transition sections 30 and 32 form a substantially concave section between the side wall 20 and the rear wall 10. This has the effect that air flowing along the side wall 20 is directed around towards the rear wall 10 without becoming confused.

Figure 6 shows a ground run-up enclosure 40 according to several aspects of the present invention. Side walls 20 each comprise five apertures 22 within them towards the front of the ground run-up enclosure. Towards the rear of the enclosure 40 are transitions 30 and 32 which form a concave structure between the side walls 20 and the rear wall 10. The rear wall 10 has an "5" shaped inwardly facing surface 12.

Air flow from either side of the enclosure 40 is directed through the apertures 22 and entrained along the inside of the side walls 20 towards the rear wall of the enclosure 10. This reduces the confusion of air flow within the enclosure 40. Air flow generated by an engine (not shown) within the enclosure 40 is directed by the side walls 20 and transitions 30 and 32 towards the rear wall 10. The inwardly facing surface 12 of the rear wall is shaped so as to direct the air flow from the engine

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(not shown) partially upwards. The air flow which is directed partially upwards by the inwardly facing surface 12 can interact with any air flowing from outside to the rear of the enclosure 40 in a non-confused manner. in

Claims

--Claims 1. A rear wall for a ground run-up enclosure comprising an inwardly facing surface which forms an angle of between 30 degrees and 80 degrees to the ground.
2. A rear wall according to Claim 1 wherein the inwardly facing surface is substantially planar.
3. A rear wall according to Claim 1 wherein the inwardly facing surface is at least partially concave.
4. A rear wall according to Claim 1 wherein the inwardly facing surface is substantially "3" shaped.
5. A rear wall according to any preceding claim wherein the wall has a top portion which has an at least partially convex inwardly facing surface and a concave outwardly facing surface.
6. A rear wall according to any preceding claim which is scaleable in height dependent on the type of aircraft to be tested.
7. A rear wall according to any preceding claim of between 12 and 17 metres in height.

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8. A side wall for a ground run-up enclosure comprising a plurality of vertical elongate apertures within the side wall.
9. A side wall according to Claim B comprising at least three vertical elongate apertures within the side wall.
10. A side wall according to Claim 8 comprising between three and seven vertical elongate apertures within the side wall.
11. A side wall according to any of Claims 8 to 10 wherein between 10 per cent and 40 per cent of the length of the side wall comprises vertical elongate apertures.
12. A side wall according to any of Claims 8 to 11 wherein the apertures are located substantially within the front half of the side wall of the ground run-up facility.
13. A side wall according to any of Claims 8 to 12 wherein the location of the apertures varies dependent on the type of aircraft to be tested.

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14 - 14. A side wall according to any of Claims 8 to 13 wherein at least one aperture is acoustically treated.
15. A side wall according to any of Claims 8 to 14 wherein at least one aperture is angled with respect to the side wall so that the portion of the aperture at the outside of the wall is nearer to the rear of the ground run-up facility than the portion of the aperture at the inside of the wall. I0
16. A side wall according to Claim 15 wherein at least one aperture is angled at between 30 and sixty degrees to the side wall.
17. A side wall according to any of Claims 14 to 16 wherein at least one aperture is equipped with acoustic silencers constructed utilising a perforate steel face sheet with an acoustic medium behind it.
18. A ground run-up enclosure comprising a transition between at least one side wall and the rear wall to form a substantially concave configuration.
19. A transition according to Claim 18 oomprising at least one planar surface.

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20. A transition according to Claim 18 or Claim 19 comprising at least two discrete changes in the same direction in angle between the side wall and the rear wall.
21. A transition according to any of Claims 18 to 20 comprising an at least partially curved surface.
22. A ground run-up facility comprising: a rear wall with an inwardly facing surface which forms an angle of between 30 degrees and 80 degrees to the ground; at least one side wall which comprises a plurality of vertical elongate apertures within it; and a transition between the at least one side wall and the rear wall to form a substantially concave configuration.
23. A ground run-up facility comprising any of the features of any preceding claim in combination.
24. A ground run-up facility substantially as described herein with reference to any of Figures 1, 3, 5 or 6.

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25. A rear wall for a ground run-up facility substantially as described herein with reference to Figure 1.
26. A side wall for a ground run-up facility substantially as described herein with reference to Figure 3.
27. A transition for a ground run-up facility substantially as describe herein with reference to Figure 5.