GB2288209A - Gas flow noise suppressor - Google Patents

Gas flow noise suppressor Download PDF

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Publication number
GB2288209A
GB2288209A GB9406283A GB9406283A GB2288209A GB 2288209 A GB2288209 A GB 2288209A GB 9406283 A GB9406283 A GB 9406283A GB 9406283 A GB9406283 A GB 9406283A GB 2288209 A GB2288209 A GB 2288209A
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GB
United Kingdom
Prior art keywords
duct
passages
noise suppressor
deflecting member
inlet ends
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9406283A
Other versions
GB9406283D0 (en
Inventor
Colin Robb Mcchesney
Christopher Freeman
Michael Sherwood
Mason Andrew Levy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rolls Royce PLC
Original Assignee
Rolls Royce PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rolls Royce PLC filed Critical Rolls Royce PLC
Priority to GB9406283A priority Critical patent/GB2288209A/en
Publication of GB9406283D0 publication Critical patent/GB9406283D0/en
Publication of GB2288209A publication Critical patent/GB2288209A/en
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/46—Nozzles having means for adding air to the jet or for augmenting the mixing region between the jet and the ambient air, e.g. for silencing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
    • B64F1/00—Ground or aircraft-carrier-deck installations
    • B64F1/26—Ground or aircraft-carrier-deck installations for reducing engine or jet noise; Protecting airports from jet erosion
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/003—Arrangements for testing or measuring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/30—Exhaust heads, chambers, or the like
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/96—Preventing, counteracting or reducing vibration or noise

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Exhaust Silencers (AREA)

Abstract

A noise suppressor for a gas turbine engine test bed comprises a duct 18 through which the engine exhaust gases B, C flow. The duct 18 has a deflecting member 56 located on the centre line T of the duct to deflect the high velocity exhaust gases from the central region L towards the intermediate region M of the duct. Two sets of pipes 58A, 58B direct entrained air D at the outer region N of the duct 18 to the intermediate region M of the duct to mix with the exhaust gases deflected by the member. A third set of pipes 72 directs air into intermediate region M of the duct to mix with the exhaust gases. The noise suppressor causes the proportion of noise below 60 Hz to be reduced while increasing the proportion of noise above 100 Hz, which can be absorbed more easily. <IMAGE>

Description

A NOISE SUPPRESSOR The present invention relates to a noise suppressor for high velocity gas streams, particularly for high velocity exhaust gases of gas turbine engines. The present invention is of particular importance for the suppression of low frequency noise, particularly in the range below about 60 Hz, which is generated by aero, industrial and marine gas turbine engines being tested in a test bed, although it may also be used for industrial and marine gas turbine engines.
Conventionally a test bed for a gas turbine engine comprises a test cell building having an air inlet at one end and an exhaust duct at the other end. The gas turbine engine to be tested is positioned within the test cell building. The exhaust duct allows the high velocity exhaust gases from the gas turbine engine to be discharged from the test cell building. The exhaust duct comprises an inlet leading to a horizontal portion and a vertical portion leading to an outlet. A set of turning vanes are provided at the junction between the horizontal portion and the vertical portion to direct the exhaust gases vertically.The vertical portion of the duct is provided with conventional sound suppressors for example the duct has a series of perforate sheets extending across it to raise the frequency of the sound generated and also the walls of the duct are perforated and are surrounded with sound absorbing material.
Unfortunately the above arrangement does not suppress the levels of noise in the range below about 60 Hz.
The low frequency noise, in the range below about 60 Hz, is generated by the exhaust gases of gas turbines being tested in test beds is disturbing the environment of the populace in the vicinity of the test beds.
The present invention seeks to provide a noise suppressor for a high velocity gas stream which will at least reduce or overcome the above mentioned problem.
Accordingly the present invention provides a noise suppressor for a high velocity gas stream comprising a duct through which the high velocity gas stream flows, the duct having a deflecting member located on the centre line of the duct to deflect the high velocity gas stream away from the central region of the duct, means to define a plurality of passages located in the duct, each passage having an inlet end at an outer region of the duct or outside the duct, each passage having an outlet end downstream of the deflecting member or at the downstream end of the deflecting member, the passages being arranged to direct a plurality of jets of gas into the duct to mix with the high velocity gas stream to increase the proportion of noise having higher frequencies.
Preferably the defecting member deflects the high velocity gas stream towards an intermediate region of the duct, the outlet end of each passage is at an intermediate region of the duct and the passages direct a plurality of jets of gas into the intermediate region of the duct to mix with the high velocity gas stream.
The passages may have inlet ends at the outer region of the duct and the inlet ends of said passages are upstream of the deflecting member.
The passages may have inlet ends outside the duct and the inlet ends of said passages are downstream of the deflecting member.
The duct may be circular or rectangular in cross-section.
The deflecting member may be circular in cross-section.
The deflecting member may be conical.
Preferably the passages are arranged into at least one set, each set comprising a plurality of passages.
Preferably the passages in a first set have inlet ends at the outer region of the duct, the inlet ends of the passages are upstream of the deflecting member, and the passages are equi-angularly spaced.
Preferably the passages in a second set have inlet ends at the outer region of the duct, the inlet ends of the passages are upstream of the deflecting member, the passages are equi-angularly spaced, the passages in the second set are arranged circumferentially alternately with the passages in the first set.
Preferably the passages in a third set have inlet ends outside the duct and the inlet ends of the passages are downstream of the deflecting member.
Preferably the inlet ends of the passages in the first and second sets are arranged in a single plane perpendicular to the centre line of the duct.
Preferably the means to define the passages of the first set of passages are secured to the duct and to the deflecting member such that the deflecting member is supported from the duct by the means to define the passages.
Preferably the passages of the first set of passages are arranged at an angle of 40 relative to the centre line of the duct.
Preferably the passages of the second set of passages are arranged at an angle of 30 relative to the centre line of the duct Preferably the passages of the first and second sets of passages extend with radial and longitudinal components.
The passages of the first and second sets of passages may extend with tangential and longitudinal components.
The passages in a second set may have inlet ends outside the duct and the inlet ends of the passages are downstream of the deflecting member.
The passages in a first set may have inlet ends outside the duct and the inlet ends of the passages are downstream of the deflecting member.
The duct may comprise a horizontal portion, a vertical portion, and a bend interconnecting the horizontal and vertical portions, and a plurality of vanes in the bend.
Preferably the horizontal portion has the inlet of the duct and the vertical portion has the outlet of the duct.
Preferably the deflecting member is in the horizontal portion of the duct.
Preferably the deflecting member is at or adjacent the inlet of the duct.
The noise suppressor is suitable for a gas turbine engine test bed or for industrial and marine gas turbine engines.
The present invention will be more fully described by way of example with reference to the accompanying drawings, in which: Fig 1 is a cross-sectional view through a test bed having a noise suppressor according to the present invention.
Fig 2 is an enlarged cross-sectional view through the noise suppressor shown in Fig 1.
Fig 3 is a view in the direction of arrow Y in Fig 2.
Fig 4 is a view in the direction of arrow Z in Fig 3.
A test bed 10, as shown in Fig 1, comprises a test cell building 12 having at one end thereof an air inlet 14 and at the other end an exhaust efflux duct 18. The air inlet 14 conventionally comprises a row of vertically oriented slats 16, each one of which is rotatable about its own vertically extending axis X-X between a first position in which they effectively close off the air inlet 14, and a second position as shown in which they present their edges to the incoming air, thus effectively opening the air inlet 14. Situated within the test cell building 12 to take in air through air inlet 14 is a gas turbine engine 20 to be tested, which is fitted with an intake flare 22 as normal. In the present example the engine is a high bypass ratio turbofan engine such as our RB211 (Registered Trade Mark) aero engine.However, the invention is of course, applicable to the testing of other sorts of gas turbine engines, such as turbojets, low bypass ratio turbofans, and industrial or marine gas turbine engines.
When the engine is being tested it draws in atmospheric air A through air inlet 5 by means of ducted fan 24. The fan 24 passes the air to the bypass duct 26 and to the core engine 28, which contains compressor, combustor and turbine sections (not indicated). The exhaust efflux from the gas turbine engine comprises the hot efflux of combustion gases C from the core engine 28 leaving core nozzle 32 and, coaxial with and surrounding that, the relatively cool efflux of air B from the bypass duct 26, leaving bypass nozzle 30. The combined efflux B and C passes from the test cell building 12 via the exhaust efflux duct 18.
The exhaust efflux duct 18 comprises a first horizontal portion 34 and a second vertical portion 36.
The horizontal portion 34 has an inlet end 38 which opens into the test cell building 12, and the inlet end 38 has a conical flare 40. The horizontal portion 34 has a circular cross-section. The horizontal portion 34 joins with the vertical portion 36 at a bend 42, and the interior of the duct 18 is provided with a plurality of vanes 44 at the bend 42 to direct the exhaust efflux from the gas turbine engine 20 up the vertical portion 36.
The vertical portion 36 of the duct 18 is provided with conventional noise suppressors, for example the duct 18 is perforated 48 and is surrounded with noise absorbing materials 50, and plates 52 with perforations 54 are positioned across the duct 18 to increase the proportion of noise at higher frequencies, which are more easily absorbed by the noise absorbing materials 50. The exhaust efflux finally leaves the duct 18 by an outlet 46.
The exhaust efflux duct 18, as shown more clearly in figures 2, 3 and 4, also comprises a conical deflecting member 56 which is positioned on the centre line T of the duct 18 in the horizontal portion 34 of the duct 18. The conical deflecting member 56 is positioned adjacent to the inlet end 38 of the duct 18. A first set of equi-angularly spaced pipes 58A is provided in the duct 18, and the pipes 58A define a number of passages 60A.
The passages 60A have inlet ends 62A and outlet ends 64A.
The inlet ends 62A are arranged in a plane S which is perpendicular to the centre line T of the duct 18. The outlet ends 64A are arranged in a plane U which is also perpendicular to the centre line T. The inlet ends 62A of the passages 60A are arranged upstream of the conical deflecting member 56 and the inlet ends 62A are arranged at the outer region N of the duct 18. The outlet ends 64A of the passages 60A are arranged in a plane U, which is coplanar with the downstream end of the conical deflecting member 56, and the outlet ends 64A are arranged at the intermediate region M of the duct 18.
The radially outermost portion of each pipe 58A is provided with a web 66 which is fastened by means of pins 68 to a respective pair of webs 70 fastened to the duct 18. The radially innermost portion of each pipe 58A is fastened, welded or formed integral with the conical deflecting member 56 such that the pipes 58A support the conical deflecting member 56 from the duct 18. In this particular example the pipes 58A extend with radial and longitudinal components relative to the duct 18. In this example there are eight pipes 58A, and each pipe 58A is arranged at an angle of 40 relative to the centre line T of the duct 18. It can be seen that the outlet ends 64A of the passages 60A are substantially at the same radial distance from the centre line T as the downstream end of the conical deflecting member 56.
A second set of equi-angularly spaced pipes 58B is provided in the duct 18, and the pipes 58B define a number of passages 60B. The passages 60B have inlet ends 62B and outlet ends 64B. The inlet ends 62B are also arranged in the plane S. The outlet ends 64B are arranged in a plane V which is perpendicular to the centre line T. The inlet ends 62B of the passages 60B are arranged upstream of the conical deflecting member 56 and the inlet ends 62B are arranged at the outer region N of the duct 18. The outlet ends 64B of the passages 60B are arranged downstream of the downstream end of the conical deflecting member 56 and the outlet ends 64B are arranged at the intermediate region M of the duct 18.
The radially outermost portions of each pipe 58B is secured to the duct 18 in a similar manner to the pipes 58A, and similarly the radially innermost portion of each pipe 58B is secured to the conical deflecting member 56.
Again the pipes 58B extend with radial and longitudinal components relative to the duct 18. There are eight pipes 58B arranged alternately with the pipes 58A circumferentially around the duct 18. The pipes 58B are arranged at an angle of 30 relative to the centre line T of the duct 18. It can be seen that the outlet ends 64B of the passages 68B are substantially at the same radial distance from the centre line T as the downstream end of the conical deflecting member 56, but are at a slightly greater radial distance.
A third set of equi-angularly spaced pipes 72 is provided in the duct 18, and the pipes 72 define a number of passages 74. Each pipe 72 is secured at its radially outermost end to the duct 18 and each passage 74 extends through the wall of the duct 18. Each pipe 72 extends radially and is curved at its radially innermost end, so that the outlet end of the passage 74 faces in a downstream direction. In this example there are sixteen pipes 72. All of the pipes have a diameter of 6 inches (15 cm).
The inlet ends 62A and 62B of the passages 60A and 60B respectively are arranged at the same radial distance from the centre line T of the duct 18.
In operation the high velocity exhaust efflux B and C from the gas turbine engine 22 flows into the inlet end 38 of the horizontal portion 34 of the duct. The high velocity exhaust gases are deflected by the conical deflecting member 56 and move radially outwards from the central region L of the duct 18 towards the intermediate region M of the duct 18. The flow of the high velocity exhaust gases B and C into the duct 18 draws air D from within the test bed building 12, and surrounding the gas turbine engine 22, into the duct 18.The air D drawn into the duct 18 flows into the outer region N of the duct 18, and some of the air D flows through the passages 60A and 60B, hence the passages 60A and 60B direct the air as a plurality of jets of air into the intermediate and central regions M and L of the duct 18 to mix with high velocity exhaust gases deflected outwards by the deflecting member 56. The remainder of the air D flows through the outer region N of the duct 18 and mixes with the high velocity exhaust gases.
The flow of the high velocity exhaust gases through the duct 18 also induces a flow of air E through the passages 74 in the pipes 72 by the ejector effect as a result of the locally reduced pressure at the outlet ends of the passages 74. The air is drawn from the interior of the test bed building 12 and surrounding duct 18. The passages 74 inject the air into the intermediate region M of the duct 18 downstream of the conical deflecting member 56 to mix with the high velocity exhaust gases deflected outwards by the conical deflecting member 56.
The mixing of the high velocity exhaust gases and the jets of air in the intermediate and central regions of the duct reduces the proportion of low frequency noise generated but increases the proportions of high frequency noise generated, ie above 100 Hz. The high frequency noise generated is more easily absorbed by the conventional noise suppressors arranged further along the duct.
The angle of inclination selected for the pipes 58A is a compromise between the conflicting requirements of minimum angle with the centre line of the duct to obtain the maximum flow of air through the passages 60A and maximum angle for support of the conical deflecting member.
Although the description and drawings has referred to two sets of pipes 58A and 58B arranged alternately circumferentially the second set of pipes 58B are optional, because a large number of pipes in the duct may lead to blockage effects on the high velocity gas stream.
Alternatively the number of pipes 58A and 58B in the two sets may be reduced to reduce blockage effects.
It may be possible to delete the two set of pipes 58A and 58B and provide other means of support for the conical deflecting member 56 while retaining the third set of pipes 72.
The description has referred to the deflecting member being located at the inlet end of the horizontal portion of the duct, it may be possible to locate the deflecting member at other suitable positions in the duct. The deflecting member may also have any suitable shape to deflect the exhaust gases outwardly from the centre line of the duct, for example bullet shaped.
It may also be possible to arrange for the first and second sets of pipes to extend with tangential and longitudinal components rather than radial and longitudinal components. It may also be possible to have the inlets to the first and second sets of pipes in different planes, and to have the inlet ends to the first and second sets of pipes at different radial distances from the centre line of the duct. The outlet ends of the first and second pipes may be in the same or different planes and may be at the same or different radial distances from the centre line of the duct.

Claims (26)

Claims:
1. A noise suppressor for a high velocity gas stream comprising a duct through which the high velocity gas stream flows, the duct having a deflecting member located on the centre line of the duct to deflect the high velocity gas stream away from the central region of the duct, means to define a plurality of passages located in the duct, each passage having an inlet end at an outer region of the duct or outside the duct, each passage having an outlet end downstream of the deflecting member or at the downstream end of the deflecting member, the passages being arranged to direct a plurality of jets of gas into the duct to mix with the high velocity gas stream to increase the proportion of noise having higher frequencies.
2. A noise suppressor as claimed in claim 1 wherein the defecting member deflects the high velocity gas stream towards an intermediate region of the duct, the outlet end of each passage is at an intermediate region of the duct and the passages direct a plurality of jets of gas into the intermediate region of the duct to mix with the high velocity gas stream.
3. A noise suppressor as claimed in claim 1 or claim 2 wherein the passages have inlet ends at the outer region of the duct and the inlet ends of said passages are upstream of the deflecting member.
4. A noise suppressor as claimed in claim 1 or claim 2 wherein the passages have inlet ends outside the duct and the inlet ends of said passages are downstream of the deflecting member.
5. A noise suppressor as claimed in claim 1 or claim 2 wherein the duct is circular or rectangular in cross-section.
6. A noise suppressor as claimed in claim 5 wherein the deflecting member is circular in cross-section.
7. A noise suppressor as claimed in claim 6 wherein the deflecting member is conical.
8. A noise suppressor as claimed in any of claims 5 to 7 wherein the passages are arranged into at least one set, each set comprising a plurality of passages.
9. A noise suppressor as claimed in claim 8 wherein the passages in a first set have inlet ends at the outer region of the duct, the inlet ends of the passages are upstream of the deflecting member, and the passages being equi-angularly spaced.
10. A noise suppressor as claimed in claim 9 wherein the passages in a second set have inlet ends at the outer region of the duct, the inlet ends of the passages are upstream of the deflecting member, the passages being equi-angularly spaced, the passages in the second set being arranged circumferentially alternately with the passages in the first set.
11. A noise suppressor as claimed in claim 10 wherein the passages in a third set have inlet ends outside the duct and the inlet ends of the passages are downstream of the deflecting member.
12. A noise suppressor as claimed in claim 9 wherein the passages in a second set have inlet ends outside the duct and the inlet ends of the passages are downstream of the deflecting member.
13. A noise suppressor as claimed in claim 8 wherein the passages in a first set have inlet ends outside the duct and the inlet ends of the passages are downstream of the deflecting member.
14. A noise suppressor as claimed in claim 10 wherein the inlet ends of the passages in the first and second sets are arranged in a single plane perpendicular to the centre line of the duct.
15. A noise suppressor as claimed in claim 9 wherein the means to define the passages of the first set of passages are secured to the duct and to the deflecting member such that the deflecting member is supported from the duct by the means to define the passages.
16. A noise suppressor as claimed in claim 15 wherein the passages are arranged at an angle of 40 relative to the centre line of the duct.
17. A noise suppressor as claimed in claim 10 wherein 0 the passages are arranged at an angle of 30 relative to the centre line of the duct.
18. A noise suppressor as claimed in any of claims 8-11 and 14-17 wherein the passages of the first and second sets of passages extend radial and longitudinal components.
19. A noise suppressor as claimed in any of claims 8-11 and 14-17 wherein the passages of the first and second sets of passages extend with tangential and longitudinal components.
20. A noise suppressor as claimed in any of claims 1 to 19 wherein the duct comprises a horizontal portion, a vertical portion and a bend interconnecting the horizontal and vertical portions, and a plurality of vanes in the bend.
21. A noise suppressor as claimed in claim 20 wherein the horizontal portion has the inlet of the duct and the vertical portion has the outlet of the duct.
22. A noise suppressor as claimed in claim 21 wherein the deflecting member is in the horizontal portion of the duct.
23. A noise suppressor as claimed in any of claims 1 to 22 wherein the deflecting member is at or adjacent the inlet of the duct.
24. A noise suppressor substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
25. A gas turbine engine test bed comprising a noise suppressor as claimed in any of claims 1 to 24.
26. A gas turbine engine comprising a noise suppressor as claimed in any of claims 1 to 24.
GB9406283A 1994-03-30 1994-03-30 Gas flow noise suppressor Withdrawn GB2288209A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9406283A GB2288209A (en) 1994-03-30 1994-03-30 Gas flow noise suppressor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9406283A GB2288209A (en) 1994-03-30 1994-03-30 Gas flow noise suppressor

Publications (2)

Publication Number Publication Date
GB9406283D0 GB9406283D0 (en) 1994-05-25
GB2288209A true GB2288209A (en) 1995-10-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB9406283A Withdrawn GB2288209A (en) 1994-03-30 1994-03-30 Gas flow noise suppressor

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1065490A3 (en) * 1999-06-29 2004-07-28 General Electric Company Methods and apparatus for suppressing engine test cell howl
EP2386720A1 (en) * 2010-05-11 2011-11-16 Siemens Aktiengesellschaft Exhaust gas diffuser with diaphragm

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB953245A (en) * 1961-01-03 1964-03-25 Bertin & Cie Improvements in or relating to silencers for jet engines
GB967800A (en) * 1960-09-30 1964-08-26 Bertin & Cie Improvements in or relating to silencer devices
GB1007554A (en) * 1960-11-24 1965-10-13 J R Andersson & Co Ab Improvements relating to ground mufflers for jet engines

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB967800A (en) * 1960-09-30 1964-08-26 Bertin & Cie Improvements in or relating to silencer devices
GB1007554A (en) * 1960-11-24 1965-10-13 J R Andersson & Co Ab Improvements relating to ground mufflers for jet engines
GB953245A (en) * 1961-01-03 1964-03-25 Bertin & Cie Improvements in or relating to silencers for jet engines

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1065490A3 (en) * 1999-06-29 2004-07-28 General Electric Company Methods and apparatus for suppressing engine test cell howl
EP2386720A1 (en) * 2010-05-11 2011-11-16 Siemens Aktiengesellschaft Exhaust gas diffuser with diaphragm

Also Published As

Publication number Publication date
GB9406283D0 (en) 1994-05-25

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