scholarly journals Effect of Velocity Ratio on the Control of Large-Scale Structures in Mixing Layers.

1996 ◽  
Vol 62 (601) ◽  
pp. 3229-3235
Author(s):  
Toshio MIYAUCHI ◽  
Mamoru TANAHASHI ◽  
Kei MATSUOKA
Keyword(s):  
Large Scale ◽  
Velocity Ratio ◽  
Mixing Layers ◽  
Large Scale Structures ◽  
Scale Structures

Dynamics of Large-Scale Structures for Jets in a Crossflow

1999 ◽  
Vol 121 (3) ◽  
pp. 577-587 ◽  
Author(s):  
F. Muldoon ◽  
S. Acharya
Keyword(s):  
Shear Layer ◽  
Large Scale ◽  
Computational Study ◽  
Near Field ◽  
Velocity Ratio ◽  
Leeward Side ◽  
Dynamic Features ◽  
Mean Velocity ◽  
Large Scale Structures ◽  
Scale Structures

Results of a three-dimensional unsteady computational study of a row of jets injected normal to a crossflow are presented with the aim of understanding the dynamics of the large-scale structures in the region near the jet. The jet to crossflow velocity ratio is 0.5. A modified version of the computer program (INS3D), which utilizes the method of artificial compressibility, is used for the computations. Results obtained clearly indicate that the near-field large-scale structures are extremely dynamic in nature, and undergo breakup and reconnection processes. The dynamic near-field structures identified include the counterrotating vortex pair (CVP), the horseshoe vortex, wake vortex, wall vortex, and shear layer vortex. The dynamic features of these vortices are presented in this paper. The CVP is observed to be a convoluted structure interacting with the wall and horseshoe vortices. The shear layer vortices are stripped by the crossflow, and undergo pairing and stretching events in the leeward side of the jet. The wall vortex is reoriented into the upright wake system. Comparison of the predictions with mean velocity measurements is made. Reasonable agreement is observed.

The characteristics and evolution of large‐scale structures in compressible mixing layers

1995 ◽  
Vol 7 (4) ◽  
pp. 864-876 ◽  
Author(s):  
Gregory S. Elliott ◽  
Mo Samimy ◽  
Stephen A. Arnette
Keyword(s):  
Large Scale ◽  
Mixing Layers ◽  
Large Scale Structures ◽  
Scale Structures

Dynamics of Large-Scale Structures for Jets in a Crossflow

1998 ◽  
Author(s):  
Frank Muldoon ◽  
Sumanta Acharya
Keyword(s):  
Shear Layer ◽  
Large Scale ◽  
Computational Study ◽  
Near Field ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Leeward Side ◽  
Mean Velocity ◽  
Large Scale Structures ◽  
Scale Structures

Results of a three dimensional unsteady computational study of a row of jets injected normal to a cross-flow are presented with the aim of understanding the dynamics of the large scale structures in the region near the jet. The jet to cross-flow velocity ratio is .5. A modified version of the computer program (INS3D) which utilizes the method of artificial compressibility is used for the computations. Results obtained clearly indicate that the near field large scale structures are extremely dynamical in nature, and undergo breakup and reconnection processes. The dynamical near field structures identified include the counter rotating vortex pair (CVP), the horseshoe vortex, wake vortex, wall vortex and the shear layer vortex. The dynamical features of these vortices are presented in this paper. The CVP is observed to be a convoluted structure interacting with the wall and horseshoe vortices. The shear layer vortices are stripped by the crossflow, and undergo pairing and stretching events in the leeward side of the jet. The wall vortex is reoriented into the upright wake system. Comparison of the predictions with mean velocity measurements is made. Reasonable agreement is observed.

Large Scale Structures in Reacting Mixing Layers

1991 ◽  
pp. 331-343 ◽  
Author(s):  
C. Lee ◽  
R. W. Metcalfe ◽  
F. Hussain
Keyword(s):  
Large Scale ◽  
Mixing Layers ◽  
Large Scale Structures ◽  
Scale Structures

scholarly journals Control of Large-Scale Structures in Spatially Developing Mixing Layers.

1995 ◽  
Vol 61 (589) ◽  
pp. 3243-3250
Author(s):  
Toshio Miyauchi ◽  
Mamoru Tanahashi ◽  
Shinobu Tokuda ◽  
Motohiro Suzuki
Keyword(s):  
Large Scale ◽  
Mixing Layers ◽  
Large Scale Structures ◽  
Scale Structures

Coherent Structure Identification in a Lobed Mixer

1991 ◽  
Author(s):  
L. Ukeiley ◽  
D. Wick ◽  
M. Glauser
Keyword(s):  
Flow Visualization ◽  
Large Scale ◽  
Velocity Ratio ◽  
Structure Identification ◽  
Visualization Method ◽  
Streamwise Vorticity ◽  
Correlation Tensor ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Proper Orthogonal

The influence of large scale structures on the flow in a lobed mixer (a device utilized to enhance streamwise vorticity for increased mixing) is examined by a pseudo flow visualization method (v. Delville et al. 1988), and the Proper Orthogonal Decomposition (POD) (v. Lumley 1967). The pseudo flow visualization method utilizes specially designed hot wire rakes with high spatial resolution to provide the capability of plotting instantaneous velocity profiles. In this work, a rake of 15 hot wires is used to provide these profiles for a velocity ratio of 2:1, at several positions downstream of the lobed mixer. From these profiles a detailed description of the flow field is achieved. In particular, from this information, an idea of the spatial extent and shedding frequency of the large scale structures is determined. The shedding frequencies found are consistent with those found from spectral measurements. A one-dimensional version of the POD is then applied, which utilizes the measured streamwise velocity two-point correlation tensor. The pseudo flow visualization technique is then used to view the contribution from each proper orthogonal mode to the instantaneous signal and comparisons made to the full signal.

Effects of heat release on the large-scale structure in turbulent mixing layers

1989 ◽  
Vol 199 ◽  
pp. 297-332 ◽  
Author(s):  
P. A. Mcmurtry ◽  
J. J. Riley ◽  
R. W. Metcalfe
Keyword(s):  
Heat Release ◽  
Turbulent Mixing ◽  
Large Scale ◽  
Mixing Layer ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Mixing Layers ◽  
Turbulent Mixing Layer ◽  
Large Scale Structures ◽  
Scale Structures

The effects of chemical heat release on the large-scale structure in a chemically reacting, turbulent mixing layer are investigated using direct numerical simulations. Three-dimensional, time-dependent simulations are performed for a binary, single-step chemical reaction occurring across a temporally developing turbulent mixing layer. It is found that moderate heat release slows the development of the large-scale structures and shifts their wavelengths to larger scales. The resulting entrainment of reactants is reduced, decreasing the overall chemical product formation rate. The simulation results are interpreted in terms of turbulence energetics, vorticity dynamics, and stability theory. The baroclinic torque and thermal expansion in the mixing layer produce changes in the flame vortex structure that result in more diffuse vortices than in the constant-density case, resulting in lower rotation rates of the large-scale structures. Previously unexplained anomalies observed in the mean velocity profiles of reacting jets and mixing layers are shown to result from vorticity generation by baroclinic torques.

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