Effects of small backward inclination on characteristics of a stack-issued combusting transverse jet in crossflow

Transverse jets in crossflow are widely used in energy systems, especially as dilution air jets, fuel/air mixers, and combustion equipment, and have received extensive attention and plenty of research. However, the studies of the circular transverse jet issued from a circular gap at the circumferential direction of a tube in crossflow are very limited. This paper studies a relatively new jet: the circular transverse jet. Firstly, numerical calculations are conducted under different turbulence models but with the same boundary conditions. By comparing the numerical results of different turbulence models with the existing experimental data, the turbulence model which is most suitable for the numerical calculation of the circular transverse jet is selected. Then, this turbulence model is used to calculate and analyze the flow field structure and its characteristics. It is found that due to the aerodynamic barrier effect of the high-velocity jet, a negative pressure zone is formed behind the jet trajectory; the existence of the negative pressure zone causes the formation of a vortex structure and a recirculation zone downstream the circular transverse jet; and the length/width ratio of the recirculation zone does not change with the changes of the crossflow and the jet parameters. It means that the recirculation zone is a fixed shape for a definite device. This would be fundamental references for the studying of fuel/air mixing characteristics and combustion efficiency when the circular transverse jet is used as a fuel/air mixer and stable combustion system.

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Evaluation of a Machine Learning Turbulence Model in a Square Transverse Jet in Crossflow

10.1115/1.0003116v ◽

2021 ◽

Author(s):

Ruben Bruno Diaz ◽

Fabiola Paula Costa ◽

Pedro M. Milani ◽

Jesuino Takachi Tomita ◽

Cleverson Bringhenti

Keyword(s):

Machine Learning ◽

Turbulence Model ◽

Transverse Jet ◽

Jet In Crossflow

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Dispersion and upwind-side shear-layer characteristics of forward-inclined transverse jet in crossflow

Experimental Thermal and Fluid Science ◽

10.1016/j.expthermflusci.2020.110104 ◽

2020 ◽

Vol 115 ◽

pp. 110104

Author(s):

Y.A. Altaharwah ◽

R.F. Huang ◽

C.M. Hsu

Keyword(s):

Shear Layer ◽

Transverse Jet ◽

Jet In Crossflow

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The actively controlled jet in crossflow

Journal of Fluid Mechanics ◽

10.1017/s0022112001006589 ◽

2002 ◽

Vol 452 ◽

pp. 325-335 ◽

Cited By ~ 116

Author(s):

R. T. M’CLOSKEY ◽

J. M. KING ◽

L. CORTELEZZI ◽

A. R. KARAGOZIAN

Keyword(s):

Open Loop ◽

Gas Jet ◽

Exit Velocity ◽

Transverse Jet ◽

Jet In Crossflow ◽

Jet Control ◽

Clear Identification ◽

Dynamic Compensator ◽

Rms Amplitude ◽

Temporal Pulse

This study quantifies the dynamics of actuation for the temporally forced, round gas jet injected transversely into a crossflow, and incorporates these dynamics in developing a methodology for open loop jet control. A linear model for the dynamics of the forced jet actuation is used to develop a dynamic compensator for the actuator. When the compensator is applied, it allows the jet to be forced in a manner which results in a more precisely prescribed, temporally varying exit velocity, the RMS amplitude of perturbation of which can be made independent of the forcing frequency. Use of the compensator allows straightforward comparisons among different conditions for jet excitation. Clear identification can be made of specific excitation frequencies and characteristic temporal pulse widths which optimize transverse jet penetration and spread through the formation of distinct, deeply penetrating vortex structures.

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Flow Dynamics and Mixing of a Transverse Jet in Crossflow—Part I: Steady Crossflow

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4035808 ◽

2017 ◽

Vol 139 (8) ◽

Cited By ~ 6

Author(s):

Liwei Zhang ◽

Vigor Yang

Keyword(s):

System Development ◽

Flow Characteristics ◽

Mixing Efficiency ◽

Strong Impact ◽

Vortical Structures ◽

Transverse Jet ◽

Eddy Simulation ◽

Jet In Crossflow ◽

Crossflow Velocity ◽

Flow Evolution

A large-eddy-simulation-based numerical investigation of a turbulent gaseous jet in crossflow (JICF) is presented. The present work focuses on cases with a steady crossflow and two different jet-to-crossflow velocity ratios, 2 and 4, at the same jet centerline velocity of 160 m/s. Emphasis is placed on the detailed flow evolution and scalar mixing in a compressible, turbulent environment. Various flow characteristics, including jet trajectories, jet-center streamlines, vortical structures, and intrinsic instabilities, as well as their relationships with the mixing process, are examined. Mixing efficiency is quantified by the decay rate of scalar concentration, the probability density function (PDF), and the spatial and temporal mixing deficiencies. Depending on the jet-to-crossflow velocity ratios, the wake vortices downstream of the injector orifice can either separate from or connect to the main jet plume, and this has a strong impact on mixing efficiency and vortex system development. Statistical analysis is applied to explore the underlying physics, with special attention at the jet-center and transverse planes.

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Strategies for Dispersion Control by Pulsed Injection: Particle Dispersion by Jet in Crossflow

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2006-98245 ◽

2006 ◽

Author(s):

Marina Campolo ◽

Andrea Cremese ◽

Alfredo Soldati

Keyword(s):

Large Scale ◽

Stokes Equations ◽

Particle Dispersion ◽

Flow Structures ◽

Specific Flow ◽

Transverse Jet ◽

Jet In Crossflow ◽

Wide Range ◽

Pulsed Injection ◽

Evolution Dynamics

The dispersion produced by a jet injecting microparticles in a cross stream is controlled by the interaction between dispersed species and large scale time-dependent flow structures populating the transverse jet. These structures span over a wide range of spatial and temporal scales and are not equally effective in advecting and dispersing species. In many environmental and industrial applications, the species advected by the jet stream are expected to undergo rapid and homogeneous dilution away from the injection point. Preferential accumulation of particles into specific flow regions is to be avoided since this may have consequences on the overall industrial process. For instance, non uniform distribution of droplets of ammonia solution can severely downgrade the efficiency of post-combustion control devices. In a previous work (Campolo et al., 2005), we addressed the problem of identifying which of the flow structures in a jet in crossflow control the dispersion mechanisms of inertial particles, focusing specifically on the issue of their preferential distribution. Based on these results, in this work we try to identify a strategy for particle pulsed injection which can be used to optimize their dispersion. The flow field produced by the transverse jet is calculated using a finite volume solver of Navier-Stokes equations; the dispersion of injected particles is computed using a Lagrangian approach. Particle dispersion and segregation are evaluated considering the effect of the synchronicity between the particle injection time and the evolution dynamics of the mixing structures. Numerical results show that (i) transport of species is dominated by specific flow structures, (ii) particle dispersion is not uniform and (iii) the synchronicity between species injection and evolution dynamics of flow structures influences the dispersion process. These results indicate that pulsed injection may be used to control effectively particle dispersion.

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Active control of flow boiling oscillation amplitude and frequency using a transverse jet in crossflow

Applied Physics Letters ◽

10.1063/1.4945334 ◽

2016 ◽

Vol 108 (13) ◽

pp. 134104 ◽

Cited By ~ 9

Author(s):

Ashwin Kumar Vutha ◽

Sameer Raghavendra Rao ◽

Farzad Houshmand ◽

Yoav Peles

Keyword(s):

Active Control ◽

Flow Boiling ◽

Oscillation Amplitude ◽

Transverse Jet ◽

Jet In Crossflow ◽

Control Of Flow

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Flow Dynamics and Mixing of a Transverse Jet in Crossflow—Part II: Oscillating Crossflow

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4035809 ◽

2017 ◽

Vol 139 (8) ◽

Cited By ~ 1

Author(s):

Liwei Zhang ◽

Vigor Yang

Keyword(s):

Velocity Ratio ◽

Vertical Movement ◽

Flow Dynamics ◽

Upstream Region ◽

Mixing Zone ◽

Transverse Jet ◽

Jet In Crossflow ◽

Power Spectral ◽

Crossflow Velocity ◽

Proper Orthogonal

The present work extends Part I of our study to investigate the flow dynamics and scalar mixing of a turbulent gaseous jet in an oscillating crossflow. Attention is first given to intrinsic flow instabilities under a steady condition. Both power spectral density and proper orthogonal decomposition analyses are applied. For the case with a jet-to-crossflow velocity ratio of 4, the two most dynamic modes, corresponding to jet Strouhal numbers of around 0.1 and 0.7, are identified as being closely linked to the shear-layer vortices near the injector orifice and the vertical movement in the jet wake region, respectively. The effect of oscillation imposed externally in the upstream region of the crossflow is also examined systemically at a jet-to-crossflow velocity ratio of 4. A broad range of forcing frequencies and amplitudes are considered. Results reveal that the dominant structures observed in the case with a steady crossflow are suppressed by the harmonic excitations. Flapping–detaching motions, bearing the forcing frequencies and their subharmonics, become dominant as the forcing amplitude increases. The ensuing flow motions lead to the formation of a long, narrow jet plume and a relatively low mixing zone, which substantially alters the mixing efficiencies as compared to the case with a steady crossflow.

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