High-Speed Turbofan Noise Reduction Using Foam-Metal Liner Over-the-Rotor

This paper focuses on the development and exploitation of a multi-disciplinary, optimization-assisted, design methodology for contra-rotating open-rotors. The design procedure relies on a two-step approach. An aero-mechanical optimization is first performed to generate a geometry with good performances over several high-speed points representative of a mission. This geometry is subsequently used as the baseline of an aero-mechanical-acoustic optimization focusing on interaction noise reduction at Cutback and Sideline low-speed points. In terms of design parameters, both rotors are modified for the first phase but only the upper part of the front rotor is altered for the noise minimization. A fully-automatic high-fidelity aero-mechanical-acoustic computational chain with fluid-structure coupling is exploited in combination with evolutionary algorithms assisted by surrogate models for the constrained-optimization process. The acoustic footprint is estimated by a simplified but fast and relevant formulation combining an unsteady lifting-line and an acoustic propagation method. The best geometry of the first design gains 1.2pt in weighted efficiency while respecting all the aero-mechanical constraints. The acoustic optimization shows that noise reduction at Sideline and Cutback points is strongly antagonistic. However, significant Sideline noise reduction from 3.5 to 5.5dB depending on the harmonics is achieved while maintaining Cutback noise and without major degradation of high-speed efficiency.

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Simulation Analysis on Noise Reduction Effect of Sound Barriers with Different Geometric Shapes for High-Speed Train

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/612/5/052038 ◽

2019 ◽

Vol 612 ◽

pp. 052038

Author(s):

Gengfei Liu ◽

Ruxiao Wang ◽

Xiaori Liu ◽

Su Li ◽

Chang Tong

Keyword(s):

Noise Reduction ◽

High Speed ◽

Simulation Analysis ◽

High Speed Train ◽

Geometric Shapes ◽

Sound Barriers ◽

Reduction Effect

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Influence of Top Shape on Noise Reduction Effect of High-Speed Railway Noise Barrier

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/493/1/012043 ◽

2019 ◽

Vol 493 ◽

pp. 012043 ◽

Cited By ~ 1

Author(s):

Wenjuan Sun ◽

Li Liu ◽

Hongli Yuan ◽

Qiaoping Su

Keyword(s):

Noise Reduction ◽

High Speed ◽

High Speed Railway ◽

Railway Noise ◽

Noise Barrier ◽

Reduction Effect

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High-Speed Jet Noise Reduction Using Microjets on a Jet Engine

10th AIAA/CEAS Aeroacoustics Conference ◽

10.2514/6.2004-2969 ◽

2004 ◽

Cited By ~ 9

Author(s):

Brenton Greska ◽

Anjaneyulu Krothapalli ◽

Nathan Burnside ◽

William Horne

Keyword(s):

Noise Reduction ◽

High Speed ◽

Jet Noise ◽

Jet Engine

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Low noise with wood milling "Airface" constructions

Annals of WULS, Forestry and Wood Technology ◽

10.5604/01.3001.0013.7736 ◽

2019 ◽

Vol 106 ◽

pp. 49-56

Author(s):

GRZEGORZ WIELOCH

Keyword(s):

Noise Reduction ◽

High Speed ◽

Air Flow ◽

Low Noise ◽

Bearing Surface ◽

Wood Industry ◽

Wood Processing ◽

New Methods ◽

Grooved Surface ◽

Milling Tools

Low noise with wood milling"airface" constructions. The noise surrounds us everywhere, constituting a disruptive component of our lives. In the wood industry it is more than in other industries due to the specificity of wood processing carried out by high-speed tools. GUS data say that in 2012 as many as 53% of employees worked in noise. Hence the necessity of constant search for new methods of noise reduction. One of them is the use of a grooved surface patterned on the plumage of owls in the construction of milling heads. Their characteristic construction makes the flight of owls almost silent. this is possible due to the special construction of ailerons, which form the bearing surface of the wing. The "owl's wing" smoothes the air flow with a serrated edge and scatters the noise. This allows for almost silent flight characteristics without adversely affecting aerodynamics. Leuco has used this concept of learning from nature to make the milling tools even more aerodynamic, and to get further noise reduction effects! Leuco has submitted a patent for this aerodynamic head design called "airface".

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