AWC17 Keynote: Flow-Excited Acoustic Resonances

ziada portrait

 

Dr. Samir Ziada is a Professor at McMaster University and former Chair of the Department of Mechanical Engineering. He had 17 years of industrial experience in the Laboratory of Fluid Mechanics and Acoustics of Sulzer Innotec Ltd in Switzerland, before joining McMaster University in Canada in 1998. He has received several awards, including the Premier Research Excellence Award of Ontario, the McMaster Student Union Award for Excellence in Undergraduate Teaching and the McMaster President Award for Excellence of Graduate Supervision. Dr. Ziada’s research expertise is in the areas of industrial aeroacoustics, flow-induced vibration and unsteady flows. He has published more than 200 papers, the majority of which are in the area of flow-sound interaction mechanisms and their control. He has also been invited to present several Keynote lectures in International conferences and academic institutions. He is currently a regular consultant to several industrial institutions, including the US Nuclear Regulatory Commission, Argonne National Laboratory, Brookhaven National Laboratory, among others. He served as an Associate Editor for the Journal of Fluids and Structures and the ASME Journal of Pressure Vessel Technology. Dr. Ziada is a Fellow of the ASME and the CSME and has been the Chair of the ASME Technical Committee on Fluid-Structure-Interaction.


FLOW-EXCITED ACOUSTIC RESONANCES IN SHALLOW CAVITIES

The excitation of acoustic resonances within ducted shallow cavities is often encountered in various components of nuclear and conventional power plants, jet engines, turbo-compressors and other engineering equipment. First, the feedback excitation mechanism causing these acoustic resonances will be introduced together with the main characteristics of various acoustic modes and flow excitation sources. Attention will then be focused on how experimental and numerical techniques can be used to explore the complex flow-sound interaction patterns inside a resonant shallow cavity. Unsteady pressure measurements at various azimuthal locations within the cavity, time resolved Particle Image Velocimetry (PIV) technique, and numerical simulation of the resonant acoustic modes with the aid of finite element analysis are used to visualize the unsteady flow structures and the acoustic mode shapes. Three different interaction patterns are analyzed, corresponding to the resonance of a single stationary acoustic mode, simultaneous excitation of two different stationary acoustic modes, and a special case of spinning mode resonance due to the excitation of two degenerate acoustic modes. The results of this study substantially improve our understanding of this complex excitation mechanism and the acquired flow visualization images constitute a challenging benchmark case for the validation of Computation Aero-Acoustic (CAA) codes.



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