Large eddy simulations of a transcritical round jet submitted to transverse acoustic modulation

2016 ◽  
Vol 28 (5) ◽  
pp. 055106 ◽  
Author(s):  
M. Gonzalez-Flesca ◽  
T. Schmitt ◽  
S. Ducruix ◽  
S. Candel
Keyword(s):  
Large Eddy Simulations ◽  
Round Jet ◽  
Transverse Acoustic ◽  
Large Eddy ◽  
Acoustic Modulation

Large-eddy simulations of a round jet in crossflow

1999 ◽  
Vol 379 ◽  
pp. 71-104 ◽  
Author(s):  
LESTER L. YUAN ◽  
ROBERT L. STREET ◽  
JOEL H. FERZIGER
Keyword(s):  
Coherent Structures ◽  
Vortex Pair ◽  
Large Eddy Simulations ◽  
Back Side ◽  
Round Jet ◽  
Turbulent Statistics ◽  
Jet Trajectory ◽  
Large Eddy ◽  
Crossflow Velocity ◽  
Counter Rotating Vortex Pair

This paper reports on a series of large-eddy simulations of a round jet issuing normally into a crossflow. Simulations were performed at two jet-to-crossflow velocity ratios, 2.0 and 3.3, and two Reynolds numbers, 1050 and 2100, based on crossflow velocity and jet diameter. Mean and turbulent statistics computed from the simulations match experimental measurements reasonably well. Large-scale coherent structures observed in experimental flow visualizations are reproduced by the simulations, and the mechanisms by which these structures form are described. The effects of coherent structures upon the evolution of mean velocities, resolved Reynolds stresses, and turbulent kinetic energy along the centreplane are discussed. In this paper, the ubiquitous far-field counter-rotating vortex pair is shown to originate from a pair of quasi-steady ‘hanging’ vortices. These vortices form in the skewed mixing layer that develops between jet and crossflow fluid on the lateral edges of the jet. Axial flow through the hanging vortex transports vortical fluid from the near-wall boundary layer of the incoming pipe flow to the back side of the jet. There, the hanging vortex encounters an adverse pressure gradient and breaks down. As this breakdown occurs, the vortex diameter expands dramatically, and a weak counter-rotating vortex pair is formed that is aligned with the jet trajectory.

scholarly journals Effect of Modulation of the Inlet Velocity and Equivalence Ratio Gradients on the Stabilization of Stratified Axisymmetric Bluff-Body Flames

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
G. Paterakis ◽  
P. Koutmos
Keyword(s):  
Bluff Body ◽  
Recirculation Region ◽  
Propane Combustion ◽  
Inlet Velocity ◽  
Transverse Acoustic ◽  
Large Eddy ◽  
Gradient Measurements ◽  
Inlet Conditions ◽  
Acoustic Modulation ◽  
The Impact

An investigation of ultralean stratified, disk stabilized, propane flames operated with acoustic modulation of the inlet velocity and fuel-air mixture profiles is presented. Transverse acoustic forcing was applied to the air, upstream of a double-cavity premixer section, formed along three concentric disks, which fueled the stabilization region with a radial mixture gradient. Measurements and supporting Large Eddy Simulations with a nine-step mechanism for propane combustion were performed to evaluate variations in the ultralean flame characteristics under forced and unforced conditions. The effects of forcing on the heat release profiles and on the interaction of the toroidal flame with the recirculation region are examined and discussed. The impact of the acoustic excitation of inlet conditions on the local extinction behavior is, also, assessed by monitoring a local stability criterion and by analyzing phase-resolved chemiluminescence images.

Automotive Flow and Acoustic Predictions using Large Eddy Simulations

2012 ◽  
Vol 39 (3) ◽  
pp. 272-289 ◽  
Author(s):  
Bahram Khalighi ◽  
Gianluca Iaccarino ◽  
Yaser Khalighi
Keyword(s):  
Large Eddy Simulations ◽  
Large Eddy

Large-eddy simulations and lidar measurements of vortex-pair breakup in aircraft wakes

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 1439-1445 ◽  
Author(s):  
D. C. Lewellen ◽  
W. S. Lewellen ◽  
L. R. Poole ◽  
C. A. Hostetler ◽  
R. J. DeCoursey ◽  
...  
Keyword(s):  
Vortex Pair ◽  
Large Eddy Simulations ◽  
Large Eddy ◽  
Lidar Measurements
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