Journal ArticleDOI
The evolution of instabilities in the axisymmetric jet. I - The linear growth of disturbances near the nozzle. II - The flow resulting from the interaction between two waves
J. Cohen,Israel Wygnanski +1 more
TLDR
In this article, the modal distribution of coherent structures evolving near the nozzle of a circular jet was studied experimentally and theoretically, with particular attention given to the effects produced on the instability modes by transverse curvature, flow divergence, inhomogeneous inflow conditions, and the detailed shape of the mean velocity profile.Abstract:
The modal distribution of coherent structures evolving near the nozzle of a circular jet was studied experimentally and theoretically, with particular attention given to the effects produced on the instability modes by transverse curvature, flow divergence, inhomogeneous inflow conditions, and the detailed shape of the mean velocity profile. Experiments were performed using a specially constructed air-jet facility; hot-wire anemometers were used in conjunction with Disa Model 55P11 sensors for flow measurements. The linear model used as a transfer function is capable of predicting the spectral distribution of the velocity perturbations in a jet. Consideration was also given to studies of leading nonlinear interactions generated by waves externally superimposed on an axisymmetric jet; theoretical predictions were verified experimentally.read more
Citations
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Journal ArticleDOI
Active control of high-speed and high-Reynolds-number jets using plasma actuators
TL;DR: In this paper, an axisymmetric Mach 1.3 ideally expanded jet of 2.54 cm exit diameter and a Reynolds number based on the nozzle exit diameter of about 1.1×106.
Journal ArticleDOI
Three-dimensional coherent structures in a swirling jet undergoing vortex breakdown: stability analysis and empirical mode construction
Kilian Oberleithner,Moritz Sieber,Christian Navid Nayeri,Christian Oliver Paschereit,Christoph Petz,Hans-Christian Hege,Bernd R. Noack,Israel Wygnanski +7 more
TL;DR: In this paper, a 3D oscillatory flow is constructed from uncorrelated 2D snapshots of particle image velocimetry data, using proper orthogonal decomposition, a phase-averaging technique and an azimuthal symmetry associated with helical structures.
Journal ArticleDOI
Jet vectoring using synthetic jets
Barton L. Smith,Ari Glezer +1 more
TL;DR: In this paper, the interaction between a conventional rectangular (primary) air jet and a co-flowing synthetic jet was investigated experimentally and the response of the primary jet to the imposed vectoring was investigated using stepped modulation of the driving signal.
Journal ArticleDOI
Instability wave models for the near-field fluctuations of turbulent jets
K. Gudmundsson,Tim Colonius +1 more
TL;DR: In this paper, the authors investigated the extent to which pressure and velocity fluctuations in subsonic, turbulent round jets can be described as linear perturbations to the mean flow field.
References
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Journal ArticleDOI
Orderly Structure in Jet Turbulence
S. C. Crow,F. H. Champagne +1 more
TL;DR: In this paper, the authors show that a large-scale orderly pattern may exist in the noiseproducing region of a round subsonic jet by observing the evolution of orderly flow with advancing Reynolds number.
Journal ArticleDOI
On spatially growing disturbances in an inviscid shear layer
TL;DR: In this paper, the authors used the hyperbolic-tangent velocity profile of the disturbed shear layer to obtain better agreement with experimental results by means of the inviscid linearized stability theory of spatially growing disturbances.
Journal ArticleDOI
The forced mixing layer between parallel streams
D. Oster,Israel Wygnanski +1 more
TL;DR: The effect of periodic two-dimensional excitation on the development of a turbulent mixing region was studied experimentally in this article, where controlled oscillations of variable ampli- tude and frequency were applied at the initiation of mixing between two parallel air streams.
Journal ArticleDOI
Analysis of the stability of axisymmetric jets
G. K. Batchelor,A. E. Gill +1 more
TL;DR: In this article, the authors studied the stability of steady axisymmetric parallel flows of uniform fluid in the absence of rigid boundaries, and they focused on the stability characteristics in the limit of large Reynolds number and determined the (integral) value of n at which the growth rate is a maximum in these simpler circumstances.
Journal ArticleDOI
Preferred modes and the spreading rates of jets
Ephraim Gutmark,Chih-Ming Ho +1 more
TL;DR: In this article, it is suggested that extremely low-level spatially coherent disturbances in individual facilities change the initial conditions of a laminar shear layer and result in the discrepancies reported in the literature.