M. S. Howe, Contributions to the theory of aerodynamic sound, with application to excess jet noise and the theory of the flute, Journal of Fluid Mechanics, 10.1017/S0022112075002777, 71, 04, (625), (2006).
Aerodynamic noise generation in centrifugal turbomachinery The objective of this research was to identify which aspects of the fluid dynamics are associated with noise generation in centrifugal turbomachinery. Research emphasis was placed on the generation of noise at frequencies other than the blade passage tones. In order to avoid noise generated by the interaction of the discharged flow and stationary objects outside of the impeller, experiments
Jul 15, 2008 · The unsteady flow and acoustic characteristics of the flapping wing are numerically investigated for a two-dimensional model of Bombus terrestris bumblebee at hovering and forward flight conditions. The Reynolds number Re, based on the maximum translational velocity of the wing and the chord length, is 8800 and the Mach number M is 0.0485. The computational results show that the
Analysis on Physical Mechanism of Sound Generation inside Analysis of coupling aerodynamics and acoustics are performed to investigate the self-sustained oscillation and aerodynamic noise in two-dimensional flow past a cavity with length to depth ratio of 2 at subsonic speeds. The large eddy simulation (LES) equations and integral formulation of Ffowcs-Williams and Hawings (FW-H) are solved for the cavity with same conditions as experiments.
Computational aeroacoustics of phonation, Part I Oct 25, 2002 · The aerodynamic generation of sound during phonation was studied using direct numerical simulations of the airflow and the sound field in a rigid pipe with a modulated orifice. Forced oscillations with an imposed wall motion were considered, neglecting fluidstructure interactions. The compressible, two-dimensional, axisymmetric form of the NavierStokes equations were numerically
Jan 01, 2011 · An approximate decomposition of fluid-flow variables satisfying unbounded compressible NavierStokes equations into acoustically radiating and non-radiating components leads to well-defined source terms that can be identified as the physical sources of aerodynamic noise. We show that, by filtering the flow field by means of a linear convolution filter, it is possible to decompose the flow
Interaction between compressible fluid and sound in a study of the aerodynamic sound generation. In this paper, we focus on the sounding mechanism of ue instruments, e.g., recorder, ute, organ pipe, etc., whose sound source is an edge tone created by an oscillating jet being emitted from the ue, going across
Noise due to turbulent flow past a trailing edge Aug 08, 1976 · 2. J. E. FFowcs WILLIAMS and L. H. HALL 1970 Journal of Fluid Mechanics 40, 657-670. Aerodynamic sound generation by turbulent flow in the vicinity of a scattering half plane. 3. D. S. JONES 1972 Journal of the Institute of Mathematics and Its Applications 9, 114-122. Aerodynamic sound due to a source near a half plane. 4.
A theory is proposed to describe the generation of sound by turbulence at high Mach numbers. The problem is formulated most conveniently in terms of the fluctuating pressure, and a convected wave equation (2.8) is derived to describe the generation and propagation of the pressure fluctuations.
Open Journal of Fluid Dynamics - researchgate.netOpen Journal of Fluid Dynamics. Publisher: Aerodynamic Sound and Flow Field Generated from Combinational Inclined Tapered Cylinder It is thought that small hydropower generation is
Proposed Inflow/Outflow Boundary Condition for Direct Proposed Inflow/Outflow Boundary Condition for Direct Computation of Aerodynamic Sound. J. B. Freund; J. B. Freund. Stanford University, Stanford, California 94305 Journal of Fluid Mechanics, Vol. 726 POD analysis of sound generation by a turbulent jet.
Sound generation by bends and joints in ventilation ducts has been measured by Bullock  using much the same techniques as Kuhn and Morfey  for pipes and reduced to correlations as in Chapter 4 of Volume 1. Namely, the duct discharged into a reverberant room and an equivalent value of sound power inside the duct was calculated using standard end corrections.
Two-dimensional model of low Mach number vortex sound The sound generated by a vortex moving across a duct section lined with porous materials and the corresponding vortex dynamics are studied numerically in the present investigation. The combined effects of the effective fluid density, the flow resistance, the length, and the thickness of the porous linings on the vortex dynamics and sound generation are examined in detail.
Unified approach to aerodynamic sound generation in the Aug 12, 2005 · In many cases of technological interest solid boundaries play a direct role in the aerodynamic sound generation process and their presence often results in a large increase in the radiated sound. A generalized treatment of the emission of sound from solid boundaries is presented. It is then shown how the various acoustic analogy theories of aerodynamic sound generation can be
Low-frequency sound radiation and generation due to the interaction of unsteady flow with a jet pipe. Journal of Fluid Mechanics, Vol. 121, Issue. -1, p. Journal of Fluid Mechanics, Vol. 121, Issue. -1, p.