Transition to Turbulence in Swirling Jet Flows (invited)

2008 ◽  
Author(s):  
Leonhard Kleiser ◽  
Sebastian Müller
Keyword(s):  
Transition To Turbulence ◽  
Jet Flows ◽  
Swirling Jet

scholarly journals Control of a Round Jet Intermittency and Transition to Turbulence by Means of an Annular Synthetic Jet

Actuators ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 185
Author(s):  
Zuzana Antošová ◽  
Zdeněk Trávníček
Keyword(s):  
Reynolds Number ◽  
Active Control ◽  
Flow Regimes ◽  
Velocity Profiles ◽  
Synthetic Jet ◽  
Transition To Turbulence ◽  
Jet Flows ◽  
Maximal Effect ◽  
Hot Wire ◽  
Round Jet

This paper deals with active control of a continuous jet issuing from a long pipe nozzle by means of a concentrically placed annular synthetic jet. The experiments in air cover regimes of laminar, transitional, and turbulent main jet flows (Reynolds number ranges 1082–5181). The velocity profiles (time-mean and fluctuation components) of unforced and forced jets were measured using hot-wire anemometry. Six flow regimes are distinguished, and their parameter map is proposed. The possibility of turbulence reduction by forcing in transitional jets is demonstrated, and the maximal effect is revealed at Re = 2555, where the ratio of the turbulence intensities of the forced and unforced jets is decreased up to 0.45.

Transition to turbulence and noise radiation in heated coaxial jet flows

2016 ◽  
Vol 28 (4) ◽  
pp. 044103 ◽  
Author(s):  
Michael Gloor ◽  
Stefan Bühler ◽  
Leonhard Kleiser
Keyword(s):  
Transition To Turbulence ◽  
Jet Flows ◽  
Noise Radiation

Stochastic-Based RANS-LES Simulations of Swirling Turbulent Jet Flows

2017 ◽  
Vol 18 (5) ◽  
pp. 351-369 ◽  
Author(s):  
Michael K. Stoellinger ◽  
Stefan Heinz ◽  
Celestin P. Zemtsop ◽  
Harish Gopalan ◽  
Reza Mokhtarpoor
Keyword(s):  
Vortex Breakdown ◽  
Hybrid Methods ◽  
Turbulent Jet ◽  
Jet Flows ◽  
Flow Simulations ◽  
Swirling Jet ◽  
Les Model ◽  
Sound Theoretical Basis ◽  
Better Than ◽  
Good Agreement

AbstractMany turbulent flow simulations require the use of hybrid methods because LES methods are computationally too expensive and RANS methods are not sufficiently accurate. We consider a recently suggested hybrid RANS-LES model that has a sound theoretical basis: it is systematically derived from a realizable stochastic turbulence model. The model is applied to turbulent swirling and nonswirling jet flow simulations. The results are shown to be in a very good agreement with available experimental data of nonswirling and mildly swirling jet flows. Compared to commonly applied other hybrid RANS-LES methods, our RANS-LES model does not seem to suffer from the ’modeled-stress depletion’ problem that is observed in DES and IDDES simulations of nonswirling jet flows, and it performs better than segregated RANS-LES models. The results presented contribute to a better physical understanding of swirling jet flows through an explanation of conditions for the onset and the mechanism of vortex breakdown.

Numerical Analysis of Dust-Air Flows Near a Round Suction Unit, Screened by an Annular Swirling Jet. Part 1. Air-Jet Flows

2018 ◽  
Vol 59 (4) ◽  
pp. 430-433
Author(s):  
M. S. Gritskevich ◽  
K. I. Logachev ◽  
O. A. Averkova ◽  
V. A. Tkachenko
Keyword(s):  
Numerical Analysis ◽  
Jet Flows ◽  
Air Jet ◽  
Swirling Jet ◽  
Air Flows

Modeling Swirling Jet Flows Using a Hybrid RANS/LES Methodology

2008 ◽  
Author(s):  
James Chenoweth ◽  
Chandrasekhar Kannepalli ◽  
Srinivasan Arunajatesan ◽  
Ashvin Hosangadi
Keyword(s):  
Jet Flows ◽  
Swirling Jet

Turbulence Model Upgrades for Swirling Flows

2007 ◽  
Author(s):  
J. D. Chenoweth ◽  
B. York ◽  
A. Hosangadi
Keyword(s):  
Turbulence Model ◽  
Richardson Number ◽  
Vortex Breakdown ◽  
Azimuthal Velocity ◽  
Operating Conditions ◽  
Jet Flows ◽  
Data Sets ◽  
Mixing Rate ◽  
Jet Mixing ◽  
Swirling Jet

The ability to accurately model axisymmetric, turbulent swirling jet flows over a variety of inflow conditions is evaluated. The deficiency of the standard k-ε turbulence model in predicting mixing rates in flows with streamline curvature is well known. A relatively straightforward modification to this model is made based on a local value of the flux Richardson number which accounts for the azimuthal velocity and its variation. To evaluate the effectiveness of this modification two different experimental data sets are used to compare the computational results against. All calculations were performed using the structured, density based, CRAFT CFD® code utilizing a preconditioning methodology. Both cases have initial swirl distributions that are equivalent to a solid-body rotation profile, and have swirl numbers that are low enough to remain below the vortex breakdown regime. They also have non-swirling jet data available for the same geometries and operating conditions which allows the increased jet mixing rate of swirling jets over purely axial jets to be confirmed. All calculations showed a significant improvement of centerline velocity decay as well as downstream radial velocity profiles when the Richardson number correction was activated. For the case with turbulence data, the centerline decay of turbulent kinetic energy was also much improved. An important result that was discovered was the extreme sensitivity of the downstream evolution of the jet to the specification of the initial k and ε profiles, highlighting the critical need for a comprehensive experimental characterization of all flow properties at the jet exit.

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