Flap and Slat Noise

Saravana Kumar R

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Introduction

During landing and take-off phases of the flight, high-lift devicessuch as flaps and slats are deployed. Recent advancements and

research into the propulsion systems have made the enginesquieter. So, airframe noise,especially flaps, salts and landing gears,contributes a significant part to the overall noise produced during

take-off and landing.

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Flow field around flap

Two major vortex systems Upper surface vortex Side edge vortex

As we move along the chord, the merge together and form asingle system

Merging occurs at a lesser distance from leading edge for largef

Vortex breakdown

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Blowing flap

Active method Slot location based on flow field

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Blowing flap-observations

T4-deteriorated vortex B1-strengthened the vortex S4-provided a retaining wall but ineffective

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Flap fences

Passive method Lower only config, lower and upper config

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Flap fence-Results

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Flow field around slat

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Slat noise-Factors

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Porous slat

Does not support shear layer

Prevents shedding of vortices

Oscillations may be conducted through porous surface

Less fluctuating wake

Noise reduction 20 dB

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Thank you!

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