Journal ArticleDOI
Investigation of the generation of sound waves produced by turbulent jets
TLDR
In this paper, the formation of acoustic fluctuations in the half-space over a surface which contains an embedded fluctuating finite-size sink is considered on the basis of the numerical solution of the unsteady Reynolds equations.Abstract:
Free turbulent jets produce disturbances in the ambient medium which at a certain distance from the jet are perceived as sound waves. These disturbances are due to unsteady fluctuating motion of the medium in the jet flow (intermittance). The origin of the acoustic disturbances can be attributed to turbulence intermittance. Due to lowered pressure in the movable dynamic inhomogeneities of the turbulent fluid, they induce air ejection by the jet, which turns out to be fluctuating in nature, since the turbulent fluid flow is unsteady. The proposed mechanism of the generation of acoustic disturbances accompanying turbulent jet propagation is verified in numerical and experimental studies; in particular, the formation of acoustic fluctuations in the half-space over a surface which contains an embedded fluctuating finite-size sink is considered on the basis of the numerical solution of the unsteady Reynolds equations. From the results of the numerical experiment performed using large eddy simulation the fluctuating characteristics of the flow in a swirling jet and the direction of the disturbance energy flux in the ambient medium are determined. An experimental investigation of the disturbances produced by a strongly swirling jet is also carried out.read more
Citations
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Journal ArticleDOI
Investigation of noise generation by turbulent jets on the basis of numerical simulation of unsteady flow in mixing layers
TL;DR: In this article, it was shown that the turbulent jet noise is produced by large-scale motions in the mixing layer induced by turbulence intermittence, where streamlines entering into the low pressure zones and flowing around the elevated pressure zones.
Journal ArticleDOI
Development of the Strategy of Active Control of Instability Waves in Unexcited Turbulent Jets
Ivan Belyaev,O. P. Bychkov,M. Yu. Zaitsev,V. A. Kopiev,V. F. Kopiev,Nikolay Ostrikov,Georgy A. Faranosov,Sergey Chernyshev +7 more
TL;DR: In this article, the authors studied the possibility of controlling instability waves in the mixing layer of a subsonic unexcited jet using an azimuthal multimicrophone array.
Journal ArticleDOI
Investigation of flows induced by subsonic turbulent jets and their relation with the effect of static pressure reduction in a jet
TL;DR: In this paper, the interaction between turbulent jets and the ambient medium is studied on the basis of the results of measurements and numerical simulation, and it is shown that the turbulent flow and the swirl give rise to induced ejection flow toward the jet.
Journal ArticleDOI
Analysis of Noise Generation by Turbulent Jets from Consideration of Their Near Acoustic Field
TL;DR: In this paper, the authors studied the generation of acoustic waves near the boundaries of swirling and nonswirling turbulent jets outside a jet flow and identified the region in which the phase difference between pressure and velocity pulsations at fixed frequencies is 90° or more.
Journal ArticleDOI
Acoustic Characteristics of Aircraft Piston Engines
TL;DR: A brief overview of the noise generation mechanisms of piston engines is given in this paper, where spectral, energy, and spatial characteristics of the sound field are considered for engines used in aviation as a part of the power plants of light aircraft and unmanned aerial vehicles.
References
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Journal ArticleDOI
On Sound Generated Aerodynamically. I. General Theory
TL;DR: In this paper, a theory for estimating the sound radiated from a fluid flow, with rigid boundaries, which as a result of instability contains regular fluctuations or turbulence is initiated, based on the equations of motion of a gas.
Book
The Structure of Turbulent Shear Flow
TL;DR: In this paper, the authors present a method to find the optimal set of words for a given sentence in a sentence using the Bibliogr. Index Reference Record created on 2004-09-07, modified on 2016-08-08
Journal ArticleDOI
A new version of detached-eddy simulation, resistant to ambiguous grid densities
Philippe R. Spalart,Sébastien Deck,Michael Shur,Kyle D. Squires,M. Kh. Strelets,Andrey Travin +5 more
TL;DR: In this paper, the authors proposed the DES97 model, denoted DES97 from here on, which can exhibit an incorrect behavior in thin boundary layers and shallow separation regions, when the grid spacing parallel to the wall becomes less than the boundary-layer thickness.
Book ChapterDOI
Adaptation of Eddy-Viscosity Turbulence Models to Unsteady Separated Flow Behind Vehicles
F. R. Menter,M. Kuntz +1 more
TL;DR: Turbulence model development for aerodynamic applications has for many years concentrated on improving the capabilities of CFD methods for separation prediction as discussed by the authors, which has led to a series of models capable of capturing boundary layer separation in good agreement with experimental data.