Stability Analysis for Noise-Source Modeling of a Part-Span Flap

Abstract

The relevant and important flow features of the local mean flowfleld 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 flowfleld 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.