With the design of modern quiet jet engines, the airframe-generated noise of civil transports has become a major concern for noise certification and environmental considerations. Past studies have shown that the high-lift devices, such as slats and flaps, and the landing gears are major contributors to aircraft noise during approach and landing. The noise sources at a flap side edge are or primary interest in the present work. The relevant and important flow features of the local mean flowfield in the vicinity of a flap side edge are extracted from an extensive computational and experimental database. Based on the local flow features, possible mechanisms for flow-induced noise sources that are responsible for sound generation at flap side edges are conjectured. Relatively simple flow models for the dominant noise sources are proposed and developed. The models are based on the most amplified instability modes of the local shear flow. Stability analysis of the modeled flowfield provides an estimate of the frequencies associated with the local flow unsteadiness. Computed frequencies show the proper trend and are in good agreement with NASA Langley Research Center's acoustic microphone array and unsteady surface-pressure measurements.
Stability analysis for noise-source modeling of a part-span flap
Modellierung der Schallemission infolge der Umströmung einer Landeklappe
AIAA Journal ; 37 , 10 ; 1206-1212
1999
7 Seiten, 15 Bilder, 21 Quellen
Article (Journal)
English
FLUID DYNAMICS - Stability Analysis for Noise-Source Modeling of a Part-Span Flap
Online Contents | 1999
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