Title: An Aeroacoustic Characterization of a Multi-Element High-Lift Airfoil
Speaker: Kyle Pascioni, PhD Candidate, Florida State University
Date: Monday, March 20, 2017
Time: 10:30 – 11:30
Location: NIA, Room 137
Abstract: The leading edge slat of a high-lift system is known to be a large contributor to the overall radiated acoustic field from an aircraft during the approach phase of the flight path. This is due to the unsteady flow field generated in the slat-cove and near the leading edge of the main element. In an effort to understand the characteristics of the flow-induced source mechanisms, a suite of experimental measurements has been performed on a two-dimensional multi-element airfoil, namely, the MD-30P30N. Particle image velocimetry provide mean flow field and turbulence statistics to illustrate the differences associated with a change in angle of attack. Phase-averaged quantities prove shear layer instabilities to be linked to narrowband peaks found in the acoustic spectrum. Unsteady surface pressure are also acquired, displaying strong narrowband peaks and large spanwise coherence at low angles of attack, whereas the spectrum becomes predominately broadband at high angles. To localize and quantify the noise sources, phased microphone array measurements are performed on the two dimensional high-lift configuration. A Kevlar wall test section is utilized to allow the mean aerodynamic flow field to approach distributions similar to a free-air configuration, while still capable of measuring the far field acoustic signature. However, the inclusion of elastic porous sidewalls alters both aerodynamic and acoustic characteristics. Such effects are considered and accounted for. Integrated spectra from Delay and Sum and DAMAS beamforming effectively suppress background facility noise and additional noise generated at the tunnel wall/airfoil junction. Finally, temporally-resolved estimates of a low-dimensional representation of the velocity vector fields are obtained through the use of proper orthogonal decomposition and spectral linear stochastic estimation. An estimate of the pressure field is then extracted by Poisson’s equation. From this, Curle’s analogy projects the time-resolved pressure forces on the airfoil surface to further establish the connection between the dominating unsteady flow structures and the propagated noise.
Bio: Kyle Pascioni is currently a graduate research assistant at Florida State University in the mechanical engineering advised by Dr. Louis Cattafesta. Prior to this, he received his BS degree in 2011 from the University of Florida in aerospace engineering. Kyle is currently finishing his Ph.D. research and plans to complete his degree this Spring.