Wassim Kriaa

Numerical Analysis of Recirculation Bubble Sizes of Turbulent Co-Flowing Jet

Abstract This paper deals with the numerical prediction of an axisymmetric turbulent jet discharged into a co-flowing stream. Two computational codes have been employed, in-house code using the standard k-ɛ model and commercial CFD software including the standard k-ɛ and the RSM model. The main object of our research is to investigate the recirculation phenomena induced by the change of the inlet and boundary conditions. We observed different recirculating regions (central and corner) induced by the inclusion of the nozzle thickness δe. The size and the strength of these recirculation bubbles are intensified by increasing δe. We also observed that the co-flowing jet emitted with a different velocity profile generates a wide central recirculation bubble and a small corner vortex. However, the formation of the recirculation bubble is destroyed by decreasing Froude number. Furthermore, the analysis of the size and strength of the recirculation bubbles is necessary in the case of the jet pump and the flame in combustion chambers.

Numerical study of the interaction between two laminar and coaxial plane jets with variable density in an ambient fluid

Abstract In this work, we intend to solve the equations governing two laminar isothermal or non-isothermal coaxial plane jets with variable density in an ambient fluid at rest in order to study the initial conditions influence (i.e. the nozzles ejection conditions) on the jet characteristic parameters. A finite difference method is developed to solve the dimensionless Navier–Stokes and energy equations resulting from some assumptions. The discussion about the results relates primarily to the concentration core length according to the nozzles thicknesses ratios. The influences of the gas velocity and temperature resulting from the external nozzle are also examined. This made it possible to deduce correlations of practical use between these parameters in order to apply them in engineering processes.

Numerical Simulation of a Ceramic Furnace Burner - Capacity of Turbulent and Radiation Models

We intend in this work to model an industrial burner replica of the ceramic tunnel furnace of the Ceramics Modern Society (SOMOCER, TUNISIA). This study aims to evaluate the ability of turbulence and radiation models to predict the dynamics and heat transfer fields. The study is conducted by means of numerical simulations in presence of a reactive flow using the commercial code FLUENT. The 3D Navier-Stokes equations and four species transport equations are solved with the eddy-dissipation (ED) combustion model. We use three turbulence models (k- standard, k- RNG, and RSM) and two radiation models (DTRM and DO). The obtained results demonstrate that the k- standard turbulence model is unable to predict the flow characteristics whereas; the k- RNG and RSM models give a satisfying agreement with the experiments. Suitable results are provided by the DTRM radiation model; whereas, those given by the DO model can be improved.