题 目: Holographic Visualization of a Low Speed Jet
报告人: Professor J. Stuart Bolton
Ray W. Herrick Laboratories, School of Mechanical Engineering, Purdue University
时 间: 2018年5月15日10：00-11：30
地 点：机械与动力工程学院 F210会议室
邀请人: 蒋伟康教授 （振动、冲击、噪声研究所）
Dr. J. Stuart Bolton received his undergraduate degree in Mechanical Engineering from the University of Toronto and his Master’s and Ph.D. degrees from Southampton University’s Institute of Sound and Vibration Research (I.S.V.R.). In 1984, Professor Bolton joined the Faculty of the School of Mechanical Engineering at Purdue University as an Assistant Professor. He is now a Full Professor and performs his research at the Ray W. Herrick Laboratories. Since joining Purdue University, Dr. Bolton has maintained an active research program in Noise Control and related disciplines. For example, he has research interests in Acoustical Materials, Sound Field Visualization, and Acoustical and Structural Wave Propagation. Since joining Purdue, Professor. Bolton has published more than 100 refereed articles, has made more than 200 conference presentations, and has supervised more than 90 graduate students. He is a Fellow of both the Acoustical Society of America and the Institute of Noise Control Engineering. In 1999 he was awarded the Institute of Noise Control Engineering’s Outstanding Educator Award and in 2014 received the Distinguished Noise Control Engineer award: he is the only person to have received both of these awards.
Abstract： The purpose of this study was to characterize the sound emitted by a subsonic jet and to predict its farfield radiation pattern based on nearfield measurements. Here, cylindrical near-field acoustical holography (NAH) was used in combination with multi-reference, cross-spectral sound pressure measurements. A strategy for reference microphone positioning is described that accounts for the localized, random, and directional nature of the source. A 0.8 cm diameter burner was used to produce a subsonic turbulent jet with a Mach number of 0.26. Six fixed, linear arrays holding eight reference microphones apiece were disposed circumferentially around the jet. A circular array holding sixteen equally-spaced field microphones was scanned in the axial direction over the 30 cm diameter cylindrical hologram surface. The results revealed that the jet could be modeled as a combination of eleven uncorrelated dipole-, quadrupole, and octupole-like sources. This model then allowed the farfield sound pressure level of the jet to be predicted within one or two decibels. The physical significance of the many partial field components and the possible application of this procedure to larger sources will be discussed.