An assessment of trailing edge noise measurement techniques

of Dissertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy AN ASSESSMENT OF TRAILING EDGE NOISE MEASUREMENT TECHNIQUES By Christopher John Bahr May 2010 Chair: Louis N. Cattafesta, III Major: Aerospace Engineering Aircraft noise is a subject of great concern, both to aircraft designers and community planners. As air travel becomes more prevalent and populations near airports increase, noise generated by aircraft during take-off and landing must be addressed. To this end, much research has gone into quantifying and reducing the strength of major contributors to aircraft noise, such as jet engines, high-lift devices and landing gear. However, as these sources are reduced, a new tier of sources grows in relative importance. Trailing edge noise is the next major noise source which needs to be addressed if aircraft designers wish to continue their trend of making quieter aircraft with each new generation. This noise source, due to the scattering of pressure fluctuations in the wing boundary layer and near wake by the rear edge of the wing, is not fully understood, even after over thirty years of research. While theoretical models exist, developing measurement tools to validate the models is not a trivial task. Experiments performed decades ago, which were thought to have provided satisfactory data to designers, are now found to have significant flaws in their results due to instrumentation limitations. Modern experimental methods can readily show the weaknesses in the older analysis techniques, but no comprehensive set of new tools is currently available for quantifying and analyzing trailing edge noise.