Bluff body noise control

Inactive Publication Date: 2010-11-18
AIRBUS OPERATIONS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]The applicants have found that unsteady flow, around and in the wake of a flow-facing element can cause a significant contribution to creation of broadband noise. In particular, it has been noted that unsteady velocity fluctuations and / or net lift forces generated in the flow may be a key noise generating mechanism. As such embodiments of the invention utilise a flow control device downstream of the flow-facing element to reduce broadband noise.
[0007]In particular, the flow control device may be arranged to reduce the flow fluctuations due to relatively large scale flow structures in the wake. For example, the flow control device may be arranged to suppress vortex shedding downstream of the flow-facing element.
[0015]Alternatively, the flow-facing element may comprises a fairing, for locating upstream of a structural element such that, in use, airflow is at least partially diverted away from the structural element, and the flow control device may be provided between the fairing and the structural element. Such an arrangement may help reduce self-noise which may otherwise be produced by the fairing.
[0021]A further aspect of the invention comprises a method of reducing noise caused by landing gear on an aircraft including the steps of identifying a part of the landing that contributes to the noise generated by the landing gear when in flight, and providing an aircraft noise-reduction apparatus according to an embodiment of the first aspect of the invention to reduce the noise generated by said part.

Problems solved by technology

The applicants have found that unsteady flow, around and in the wake of a flow-facing element can cause a significant contribution to creation of broadband noise.
In particular, it has been noted that unsteady velocity fluctuations and / or net lift forces generated in the flow may be a key noise generating mechanism.

Method used

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  • Bluff body noise control
  • Bluff body noise control
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Examples

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Embodiment Construction

[0027]FIG. 1 shows a noise reduction apparatus in accordance with a first embodiment of the invention. The noise reduction apparatus comprises a structural element 1 which is exposed, in use, to an airflow V∞. In other words, the structural element is flow-facing. V∞ may be assumed to be the free stream airflow. In the case where the structural element 1 is a landing gear component it will be appreciated that it may be deployable, such that it is only be exposed to the airflow V∞ during take-off, landing and approach.

[0028]The structural element 1 is a bluff body, in this case a H-Beam. The skilled person will appreciate that a bluff body may be generally characterised as any body where there is significant flow separation and a generally unsteady wake.

[0029]The noise reduction apparatus further comprises a flow control device in the form of a splitter plate 2. The splitter plate 2 is a rigid plate attached to the downstream side of the structural element 1. The splitter plate 2 ext...

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PUM

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Abstract

An aircraft noise-reduction apparatus comprise a flow-facing element (1) and a flow control device (2) positioned downstream of the flow-facing element (1). The flow control device (2) is arranged, in use, to reduce noise induced by unsteady flow downstream of the flow-facing element (1).

Description

FIELD OF THE INVENTION[0001]The present invention relates to noise-reduction apparatus for use on an aircraft. More particularly, but not exclusively, the invention relates to a method of reducing noise generated by the interaction of the landing gear or parts thereof and the air flowing past it during flight, take-off and / or landing.BACKGROUND OF THE INVENTION[0002]Flow around bodies generates noise, which is detrimental in particular aerodynamic applications for example where low noise emissions are a design requirement. One such application where the level of noise emissions is important is in the design of commercial aircraft. Over the past decades engine noise has been significantly reduced, for example by the introduction of high-bypass ratio turbofan engines. However, maintaining the minimum engine ground clearance with such high-bypass ratio turbo fan engines results in longer landing gear. Thus, Landing gear on commercial aircraft have been identified as major noise contrib...

Claims

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Application Information

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IPC IPC(8): B64C23/00B64C25/02
CPCB64C21/00B64C23/00B64C25/001B64C2230/14B64C2025/003Y02T50/166B64C1/40B64C25/16Y02T50/10
InventorCHOW, LEUNG CHOISPITERI, MATTHEWZHANG, XINANGLAND, DAVIDGOODYER, MICHAEL
OwnerAIRBUS OPERATIONS LTD