In this present study, the numerical simulations are performed for an axisymmetric turbulent jet diffusion hydrogen/air flame, by using a hybrid Finite-Volume/Composition PDF-Transport method. This method represents a rational approach for the study of turbulent reacting flows containing signficant turbulencechemistry interactions. The major attraction of Composition PDF method is that the terms associated with chemical reaction appear in closed form, leaving only molecular mixing and turbulent transport terms to be modeled. The accuracy of Composition PDF model calculations depends on the accurate representation of the chemistry and on the mixing model including the value of the mixing-model constant CΦ (mixing-model constant CΦ is the mechanical to scalar time scale ratio (CΦ =τt/τΦ).There has been considerable development in the past three decades in PDF methods, and reviews can be found in Dopazo and O'Brien

In order to respond to the increased demand for clean energy without harming the atmosphere through polluting emissions, Energy production from the hydrogen combustion become largely used. This work presents a numerical study of the injection conditions effect on the structure of the H2-Air diffusion flame. The aim is to reproduce a practical case of non-polluting combustion and resulting in very high temperatures. The configuration is composed of two axisymmetric coaxial jets, as can be found in the diffusion burners. A presumed probability density function (PDF) approach is used to describe the chemistry-turbulence interaction. K-epsilon model of turbulence is used. Particular attention is given to phenomena anchoring or blowout of the flame.

This study deals with convective heat transfer in a square cavity with a localized heat source at its center. The form factor of this configuration is (h/H=0.6) which is the ratio between the height of the source and the height of the cavity. The Rayleigh number is Ra=106 that indicated a laminar flow in this cavity. The numerical simulation gives a good result compared to the experimental data, which justifies the choice of our models used in this study. The objective is to make this natural convection a forced convection by the mobility of the upper wall. This made it possible to change the concentration of the state parameters in this cavity. This result can be used to make an orientation of the heat in this cavity. We note the use of four (4) speeds of the mobile wall in order to see the influence of the speed of this north wall on the convection phenomenon.

In this paper, we focus on the effect of the inner diameter and Reynolds number on the recirculation zone in an annular jet flow with numerical simulation by resolving the Reynolds-averaged Navier-Stokes equations with the first closed model of turbulence k-epsilon. The annular jet plays an essential role in stabilizing the flame in the burner which is used in many industrial applications. The annular jet is characterized by the inner and outer diameter. In this study, three different inner diameters are adopted with constant width of the annular jet. We adopted also three different values of the Reynolds number show the effect of the Reynolds number on the recirculation zone. The simulation is realized by a CFD code which uses the finite element method. The results obtained from this study are in good agreement with the experimental data. Two recirculation zones are shown; a large recirculation zone at the outlet of the flow and a small recirculation zone just near the injection generated by the annular flow and the inner diameter Di ; it is observed that the size of the recirculation zone increases when the inner diameter increases and the length of the recirculation zone depends only on the inner diameter. This recirculation zone is also affected by the Reynolds number with a very low variation of the recirculation length.

In this paper, we investigate the no-reacting swirling flow by using the numerical simulation based to the unsteady Reynolds-averaged Navier-Stokes approach. The numerical simulation was realized by using a computational fluid dynamics CFD code. The governing equations are solved by using the finite volume method with two classical models of turbulence K-epsilon and Shear Stress K-ω. The objective of this paper is therefore to evaluate the performance of the two models in predicting the recirculation zones in a swirled turbulent flow. The current models are validated by comparing the numerical results of the axial, radial and tangential velocities to the experimental data from literature.