Numerical study of turbulent round free jet

2018 ◽  
Author(s):  
Niloy Das ◽  
S. M. Rakibul Islam ◽  
Sayeed Mohammed ◽  
Mohammad Nasim Hasan
Keyword(s):  
Numerical Study ◽  
Free Jet

Numerical Study of the Mean and Filtered Characteristics of Turbulent Jets Impinging on Convex and Flat Surfaces Using LES

2012 ◽  
Author(s):  
Adra Benhacine ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar ◽  
Nabil Kharoua
Keyword(s):  
Convex Surface ◽  
Numerical Study ◽  
Three Dimensional ◽  
Turbulent Jets ◽  
Scale Model ◽  
Wall Jet ◽  
Potential Core ◽  
Flat Surfaces ◽  
Free Jet ◽  
Eddy Simulation

A numerical study of a turbulent plane jet impinging on a convex surface and on a flat surface is presented, using the large eddy simulation approach and the Smagorinski-Lilly sub-grid-scale model. The effects of the wall curvature on the unsteady filtered, and the steady mean, parameters characterizing the dynamics of the wall jet are addressed in particular. In the free jet upstream of the impingement region, significant and fairly ordered velocity fluctuations, that are not turbulent in nature, are observed inside the potential core. Kelvin-Helmholtz instabilities in the shear layer between the jet and the surrounding air are detected in the form of wavy sheets of vorticity. Rolled up vortices are detached from these sheets in a more or less periodic manner, evolving into distorted three dimensional structures. Along the wall jet the Coanda effect causes a marked suction along the convex surface compared with the flat one. As a result, relatively important tangential velocities and a stretching of sporadic streamwise vortices are observed, leading to friction coefficient values on the curved wall higher than those on the flat wall.

Experimental and Numerical Study of Pentacene Molecular Beam Seeded in the Free Jet of Helium

2011 ◽  
Author(s):  
A. K. Rebrov ◽  
P. A. Skovorodko ◽  
T. Toccoli ◽  
M. Tonezzer ◽  
N. Coppedè ◽  
...  
Keyword(s):  
Molecular Beam ◽  
Numerical Study ◽  
Free Jet

A numerical study of the nozzle/diffuser micropump

2008 ◽  
Vol 222 (3) ◽  
pp. 525-533 ◽  
Author(s):  
K-S Yang ◽  
I-Y Chen ◽  
K-H Chien ◽  
C-C Wang
Keyword(s):  
Numerical Study ◽  
Geometric Dimension ◽  
Jet Flow ◽  
Opening Angle ◽  
Cross Sectional ◽  
Free Jet ◽  
Chamber Length ◽  
Two Factors ◽  
Versus Amplitude ◽  
Free Jet Flow

This study numerically investigates the performance of micronozzle/diffuser pump subject to the influence of frequency, opening angle, geometric dimension, and amplitude. For the effect of geometric dimension, the effect of chamber length is far more important than that of chamber depth because it can provide much more effective pumping volume. It is found that the net flowrate of a micropump increased with pumping frequency and opening angle. However, a level-off phenomenon of the net flowrate versus amplitude is seen at amplitudes nearby 150–200 μm and at an opening angle above 10°. This phenomenon is associated with two factors that compensate with each other. One is the free jet flow from the outlet that overturns and blocks the flow from the inlet. The other is the reduction of the strength of jet flow at a larger amplitude owing to effective increase of cross-sectional area.

Numerical study of MHD effect on liquid metal free jet under complex magnetic fields

2006 ◽  
Vol 81 (8-14) ◽  
pp. 1451-1458 ◽  
Author(s):  
Xiao-Yong Luo ◽  
Alice Ying ◽  
Mohamed Abdou
Keyword(s):  
Magnetic Fields ◽  
Liquid Metal ◽  
Numerical Study ◽  
Metal Free ◽  
Free Jet

Effects of the Shape of a Nozzle With Chevrons on the Dynamics of Turbulent Impinging Jet

2016 ◽  
Author(s):  
Sadek Horra ◽  
Zoubir Nemouchi ◽  
Lyes Khezzar
Keyword(s):  
Numerical Study ◽  
Three Dimensional ◽  
Impinging Jet ◽  
Point Of View ◽  
Geometrical Parameters ◽  
Free Jet ◽  
Fundamental Point ◽  
Nozzle Shape ◽  
Heat And Fluid Flow ◽  
Plate Distance

This work is a numerical study of a turbulent impinging jet issuing from a nozzle with chevrons. The Reynolds number based on the jet exit velocity and nozzle diameter is equal to 5000 corresponding to a low Mach number of 0.0057 at the nozzle exit. The main objectives of the investigation, inspired by the work of Violato et al. (Int. J. of Heat and Fluid Flow, 37, 2012), are to highlight, from a fundamental point of view, the effects of the nozzle shape and the nozzle-to-plate distance on the mean parameters characterizing the dynamics of the flow in question. The nozzle configurations considered are a circular nozzle without chevrons and nozzles provided with 4 and 6 chevrons. The nozzle-to-plate distance ranges from 2 to 6 nozzle diameters. All the other flow conditions and geometrical parameters used in the different cases treated are identical. Interesting features of the flow are revealed by the obtained results of averaged three-dimensional fields of velocity and turbulent kinetic energy, particularly close to the wall. An attempt is made to bring additional insight into the phenomena in the free jet, the impingement region and the wall jet when using 4, 6 and no chevrons, for different nozzle-to-plate distances.

Numerical study of a free jet multinozzle source

1994 ◽  
Vol 223 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Eugene V. Kuleznev ◽  
Vladimir I. Baranov ◽  
Dmitry N. Trubnikov
Keyword(s):  
Numerical Study ◽  
Free Jet

scholarly journals Numerical study of heat and mass transfer in underexpanded sonic free jet

2017 ◽  
Vol 35 (4) ◽  
pp. 959-968 ◽  
Author(s):  
Omid Adibi ◽  
Bijan Farhanieh ◽  
Hossein Afshin
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Numerical Study ◽  
Free Jet

scholarly journals Effect of Proximity to Bed on 30° and 45° Inclined Dense Jets: A Numerical Study

2021 ◽  
Author(s):  
Mohammadmehdi Ramezani ◽  
Ozeair Abessi ◽  
Ali Rahmani Firoozjaee
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Lower Boundary ◽  
Geometrical Properties ◽  
Free Jet ◽  
Rise Height ◽  
Desalination Plants ◽  
Inclined Dense Jets ◽  
Good Agreement ◽  
Return Point

Abstract Employing inclined dense jets is a common way for the disposal of brine effluent from coastal desalination plants. This paper numerically analyzes the mixing and geometrical properties of 30° and 45° inclined dense jets when they discharge close to the bed. For this purpose, two series of numerical simulations were developed. First, the nozzle acts as a free jet when it is placed far enough from the lower boundary. Meanwhile, in the second series, the distance between the nozzle tip and seabed is substantially reduced. Consequently, by comparing these two series, the effect of proximity to bed on the behavior of dense jets is investigated. The governing equations are solved by modifying a solver within the CFD package of OpenFOAM. The numerical results are presented in comparative figures and compared to the previous works. Comparisons indicated that the numerical model predicts the geometrical characteristics of dense jets in good agreement with the past experimental studies. However, the dilution predictions are conservative. It has been observed that proximity to the bed has almost no appreciable effects on the behavior of 45° jets. However, for 30° jets, when the bed proximity parameter ( Y0/LM ) falls below 0.14, normalized values of horizontal and vertical locations of centerline peak and return point dilution are slightly reduced while the terminal rise height remains untouched.

scholarly journals Numerical Study on Different Series Modes of Jet Fan in a Longitudinal Tunnel Ventilation System

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Guihong Pei ◽  
Jie Pan
Keyword(s):  
Numerical Study ◽  
Ventilation System ◽  
Original Design ◽  
Air Velocity ◽  
Central Plains ◽  
Traffic Condition ◽  
Free Jet ◽  
Combination Modes ◽  
Ventilation Performance ◽  
Combination Mode

Efficient ventilation systems will contribute to maintaining air quality in the tunnel. In order to improve ventilation performance in normal traffic condition, the 3D tunnel models were established according to the original design for the tunnel located in central plains of China. Based on the commercial CFD software Fluent 6.3 andk-εturbulence model, numerical simulations were carried out to study the patterns of jet flow and the optimization of fan combinations. It is found that the axial velocity profile obtained from numerical simulation agrees quite well with turbulent free jet theory although there is a little difference on the magnitude. The comparison of four combination modes under the condition of operating four fans indicates that the ventilation effectiveness is affected mainly by both the interval of adjacent groups of fans and the combination modes of operational fans. According to the simulation results, a novel combination mode which consists of a group double paralleled fans and two groups single fan is designed. The novel combination mode is regarded as the optimum combination mode with respect to maximizing air velocity in the tunnel. Compared to the traditional combination modes, it will increase the air velocity by 5.7%.

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