scholarly journals Transition scenario of the round jet in crossflow topology at low velocity ratios

2014 ◽  
Vol 26 (8) ◽  
pp. 084101 ◽  
Author(s):  
Tristan Cambonie ◽  
Jean-Luc Aider
Keyword(s):  
Low Velocity ◽  
Round Jet ◽  
Jet In Crossflow ◽  
Transition Scenario

Time Resolved PIV Measurements of a Slot Lobed Jet Issuing Into a Crossflow

2021 ◽  
Author(s):  
Michael Lewandowski ◽  
Paul Kristo ◽  
Abdullah Weiss ◽  
Mark Kimber
Keyword(s):  
Velocity Ratio ◽  
Leading Edge ◽  
Residual Effects ◽  
Low Velocity ◽  
Mean Velocity ◽  
Time Resolved ◽  
Freestream Velocity ◽  
Round Jet ◽  
Jet In Crossflow ◽  
Turbulent Statistics

Abstract The near field mixing phenomenon created by a round jet with three slot lobes exhausting into a crossflow are investigated at a velocity ratio of 0.5. Time-resolved particle image velocimetry measurements provide instantaneous velocity fields of the slotted jet in crossflow, allowing for evaluation of the first and second order turbulent statistics in two perpendicular planes of interest. The independently controlled jet exit and crossflow inlet are first characterized extensively to confirm the velocity ratio and anticipated momentum exchanges. Spanwise and transverse mean velocity profiles reveal that the interaction of the three slot lobes and the center round jet primarily occur in the immediate jet exit region, though residual effects are also found in the wake. Evaluation of the Reynold stresses aims to quantify the near region mixing between the jets collated geometric features and their interaction with the crossflow. Frequency analysis reveals that low-frequency harmonics in the wake region provide greater energy contributions than that of the higher-frequency harmonics found along the leading edge shear layer. This behavior is attributed to the low velocity ratio, where the freestream velocity is twice as large as the jet exit velocity. The experimental data and observations herein serve analogous computational modeling efforts for the slotted jet in crossflow at low velocity ratios, with ample information to inform necessary boundary conditions, fluid properties, and flow fields for validation.

An experimental study of oblique transition in plane Poiseuille flow

1998 ◽  
Vol 358 ◽  
pp. 177-202 ◽  
Author(s):  
PER A. ELOFSSON ◽  
P. HENRIK ALFREDSSON
Keyword(s):  
Poiseuille Flow ◽  
High Amplitude ◽  
Linear Wave ◽  
Plane Poiseuille Flow ◽  
Low Velocity ◽  
Oblique Waves ◽  
Wave Disturbances ◽  
Rapid Transition ◽  
Streamwise Streaks ◽  
Transition Scenario

Interactions of oblique waves have recently been investigated theoretically and numerically and found to give rise to rapid transition in flows subcritical to linear wave disturbances. The transition scenario consists of the formation and transient growth of streamwise streaks of high and low velocity and later a rapid growth of high-frequency disturbances leading to breakdown. The present study is the first extensive experimental investigation of oblique transition. The experiments were carried out in a plane Poiseuille flow air channel in which the oblique waves were generated, one at each wall, by vibrating ribbons and the development of the flow was mapped with hot-wire anemometry. The experiments consist both of low- and high-amplitude wave disturbances; in both cases streaky structures are created. For the low-amplitude case these structures decay, whereas for the high amplitude the flow goes towards breakdown. This study has confirmed and extended previous theoretical and numerical results showing that oblique transition may be an important transition scenario.

Large-Eddy Simulation of a Round Jet in Crossflow

AIAA Journal ◽  
2009 ◽  
Vol 47 (5) ◽  
pp. 1158-1172 ◽  
Author(s):  
Jörg Ziefle ◽  
Leonhard Kleiser
Keyword(s):  
Large Eddy Simulation ◽  
Round Jet ◽  
Eddy Simulation ◽  
Jet In Crossflow ◽  
Large Eddy

Trajectory and entrainment of a round jet in crossflow

1998 ◽  
Vol 10 (9) ◽  
pp. 2323-2335 ◽  
Author(s):  
Lester L. Yuan ◽  
Robert L. Street
Keyword(s):  
Round Jet ◽  
Jet In Crossflow

Visualization Of Vortex Structures In The Near Field Of The Round Jet Formed In Curved Channel By Piv-Method

2016 ◽  
Vol 11 (2) ◽  
pp. 103-107
Author(s):  
Maria Litvinenko ◽  
Yuriy Litvinenko ◽  
Valentin Vikhorev
Keyword(s):  
Velocity Gradient ◽  
Particle Image ◽  
Near Field ◽  
Gradient Field ◽  
Low Velocity ◽  
Round Jet ◽  
Dean Vortices ◽  
Piv Method ◽  
Image Velocimetry ◽  
Vector Velocity Field

The results of experimental investigation of the round jet with Dean vortices (Red = 4 000, De = 1 673) using Particle Image Velocimetry are presented. The measurements were performed with synchronization the phase of acoustic signal and a laser pulse. Instant picture of vorticity field ωz and vector velocity field for the U- and V-components of the jet cross-actions show Dean vortices near the output of the channel in the low velocity gradient field and Kelvin – Helmholtz vortices in the high-velocity gradient field. The presence of Dean vortices distorts two-dimensional vortex ring, which gets an Ω-shaped form, at that the « head» of Ω-vortex outpaces its «legs», as it is in a higher velocity area.

Hybrid RANS-LES Modeling of a Normal Jet in Crossflow for Film Cooling Applications

2013 ◽  
Author(s):  
Tej P. Dhakal ◽  
D. Keith Walters
Keyword(s):  
Film Cooling ◽  
Velocity Ratio ◽  
Mean Flow ◽  
Low Velocity ◽  
Lower Velocity ◽  
Jet In Crossflow ◽  
Wall Structures ◽  
Crossflow Velocity ◽  
Les Model ◽  
Near Wall

Numerical simulation of a normal jet in crossflow has been performed using a recently developed hybrid RANS-LES model. The model form utilizes a solution based parameter that dynamically determines the RANS and LES regions. Numerical simulations using commercially available DDES model and a RANS model have also been performed for comparison purposes. Three jet to crossflow velocity ratios (R = 2, 1, 0.5) have been investigated. Computational results obtained are compared with the experiment of Andreopoulos and Rodi (1984). The results highlight the predictive capabilities of hybrid RANS-LES model to reproduce the important vortical structures of a jet in crossflow case, which play a crucial role in the film cooling. The hybrid RANS-LES model results from the velocity ratio R = 2 case fare well with the experiment in comparison to RANS predictions. For lower velocity ratios, discrepancies in mean flow statistics have been observed at some measurement stations. The near wall statistics from the hybrid model resembles RANS predictions for the case with jet to crossflow velocity ratio R = 0.5. This observation can be attributed to the requirement of higher grid resolution necessary to capture the near wall structures for low velocity ratio cases.

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