Investigation on Airframe Noise Due to Flap Side Edge and Its Reduction

Speaker: Mitsuhiro Murayama, Japan Aerospace Exploration Agency (JAXA)
March 16, 2016

Presentation

Abstract

Noise from trailing-edge flaps deployed during landing and take-off to increase lift is known to be one of the major sources of airframe noise. The flap side-edge where tip vortices are generated is a primary contributor to the flap noise. Several noise reduction concepts have been proposed for the flap side-edge in the past, but they mostly had to depend on a parametric study in wind tunnel tests. By revealing the details of the underlying unsteady flow field and the resulting noise characteristics, computational investigations can greatly aid the understanding of the noise generation mechanisms and help low noise design. Therefore, JAXA has been using a synergistic combination of computational methods and wind tunnel tests to study airframe noise sources and techniques to reduce them.

This presentation will focus on the effect of variations in the flap side edge shape on both the flowfield and the far-field noise. The broadband noise results from unsteady fluctuations associated with instabilities of the separated flow around the side-edge of flap and near the gap between the main wing and the flap. Several flap side-edge configurations including rounded flap side-edges, a side-edge with cavity, and a protrusion on the lower surface of the flap are investigated as potential means for suitable alterations to the unsteady fluctuations. Results from a variety of computations and wind tunnel tests will be used to discuss the physical mechanisms underlying noise generation near the flap side edge and its reduction via changes in the edge geometry.

Biography

Murayama received his Ph.D. in Aeronautics and Space Engineering from Tohoku University (Japan) in 2003 and has been working at JAXA since then. He is presently working as a member of the project team on Flight demonstration of QUiet technology to Reduce nOise from High-lift configurations (FQUROH). During his tenure at JAXA, Murayama has also held visiting appointments in the Aerodynamics and performance group at the Mitsubishi Aircraft Corporation, Japan, and in the Computational Fluid Dynamics and Aeroacoustics Department (DSNA) at ONERA, France. He has served on the organizing committees for the AIAA CFD Drag Prediction Workshop (DPW) and AIAA CFD High Lift Prediction Workshop (HiLiftPW) and has also been a key contributor to the AIAA workshop series on Benchmark Problems for Airframe Noise Computations (BANC).

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