TY - JOUR
T1 - A throttling mechanism sustaining a hole tone feedback system at very low Mach numbers
AU - Matsuura, K.
AU - Nakano, M.
N1 - Funding Information:
This research was supported by the Global COE Program ‘World Center for Education and Research for Trans-disciplinary Flow Dynamics’, of Tohoku University. Computational resources were provided by the Advanced Fluid Information Research Center of the Institute of Fluid Science, and also by the Cyberscience Center, Tohoku University. The experiment was conducted with the cooperation of Mr A. Totsuka, a technician at the Institute of Fluid Science, Tohoku University.
Publisher Copyright:
© Cambridge University Press 2012.
Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 2012
Y1 - 2012
N2 - This study investigates the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. Direct computations of a hole tone feedback system were conducted. The mean velocity of the air jet was 10 m s-1. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length between the nozzle and the end plate was 50 mm. The computational results agreed well with past experimental data in terms of qualitative vortical structures, the relationship between the most dominant hole tone peak frequency and the jet speed, and downstream growth of the mean jet profiles. Based on the computational results, the shear-layer impingement on the hole edge, the resulting propagation of pressure waves and the associated vortical structures are discussed. To extract dominant unsteady behaviours of the hole tone phenomena, a snapshot proper orthogonal decomposition (POD) analysis of pressure fluctuation fields was conducted. It was found that the pressure fluctuation fields and the time variation of mass flows through the end plate hole were dominantly expressed by the first and second POD modes, respectively. Integrating the computational results, an axisymmetric throttling mechanism linking mass flow rates through the hole, vortex impingement and global pressure propagation, is proposed.
AB - This study investigates the sound produced when a jet, issued from a circular nozzle or hole in a plate, goes through a similar hole in a second plate. The sound, known as a hole tone, is encountered in many practical engineering situations. Direct computations of a hole tone feedback system were conducted. The mean velocity of the air jet was 10 m s-1. The nozzle and the end plate hole both had a diameter of 51 mm, and the impingement length between the nozzle and the end plate was 50 mm. The computational results agreed well with past experimental data in terms of qualitative vortical structures, the relationship between the most dominant hole tone peak frequency and the jet speed, and downstream growth of the mean jet profiles. Based on the computational results, the shear-layer impingement on the hole edge, the resulting propagation of pressure waves and the associated vortical structures are discussed. To extract dominant unsteady behaviours of the hole tone phenomena, a snapshot proper orthogonal decomposition (POD) analysis of pressure fluctuation fields was conducted. It was found that the pressure fluctuation fields and the time variation of mass flows through the end plate hole were dominantly expressed by the first and second POD modes, respectively. Integrating the computational results, an axisymmetric throttling mechanism linking mass flow rates through the hole, vortex impingement and global pressure propagation, is proposed.
KW - Absolute/convective instability
KW - Aeroacoustics
KW - Jets
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U2 - 10.1017/jfm.2012.377
DO - 10.1017/jfm.2012.377
M3 - Article
AN - SCOPUS:84971350186
VL - 710
SP - 569
EP - 605
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
SN - 0022-1120
ER -