a b s t r a c tEffects of hydrogen enrichment and steam addition on laminar burning velocity of methaneeair premixed flame were studied both experimentally and numerically.Measurements were carried out using the slot burner method at 1 bar for fresh gases temperatures of 27 C and 57 C and for variable equivalence ratios going from 0.8 to 1.2.The hydrogen content in the fuel was varied from 0% to 30% in volume and the steam content in the air was varied from 0 to 112 g/kg (0e100% of relative humidity). Numerical calculations were performed using the COSILAB code with the GRI-Mech 3.0 mechanism for one-dimensional premixed flames. The calculations were implemented first at room temperature and pressure and then extended to higher temperatures (up to 917 K) and pressures (up to 50 bar). Measurements of laminar burning velocities of methanee hydrogeneair and methaneeairesteam agree with the GRI-Mech calculations and previous measurements from literature obtained by different methods. Results show that enrichment by hydrogen increases of the laminar burning velocity and the adiabatic flame temperature. The addition of steam to a methaneeair mixture noticeably decreases the burning velocity and the adiabatic flame temperature. Modeling shows that isentropic compression of fresh gases leads to the increase of laminar burning velocity.

This paper reports a numerical investigation of an atmospheric lean-premixed swirl-stabilized burner. The focus on the flow behavior and flame stability is done at various swirl intensity to better understand the propane turbulent premixed flames. The numerical simulation is carried out using RANS technique with three turbulence closer models Standard k-ε, Realizable k-ε and SST k-ω. This in order to evaluate the performance of these models in the prediction of confined turbulent swirling flows. The turbulence-chemistry interaction scheme is modelled using Finite Rate-Eddy Dissipation model with three step global reaction mechanism. The combustor is operated with air and propane mixture under an atmospheric pressure at a global equivalence ratio of Φ = 0.5. The investigation is done using five different swirl numbers Sn = (0, 0.35, 0.75, 1.05, 1.4), including a validation with the available experimental data. Good agreement is found between RANS results and experimental data, in particular axial and radial velocity profiles, temperature and propane concentration profiles. Results indicate the presence of outer recirculation zone (ORZ) in the inlet burner corner, irrespective of the swirl number. When the swirl number reaches a critical value Sn = 0.75, an inner recirculation zone (IRZ) appears in the center of the burner inlet as a result of vortex-breakdown. Increasing swirl number to an excessive value leads to the propagation of the IRZ upstream the combustion chamber, and consequently the appearance of the flame flashback.

A V-flame stabilized by a vertical cylindrical rod in an annular jet is positioned at different points of an acoustic transverse field. Original mechanisms highlight flame and flow dynamics: vertical mass flow rate modulation resulting from a longitudinal-type wave induced by the pressure fluctuations of the transverse wave; jet and flame dissymmetry caused by acoustic energy effects; CH* emission modulations, related to heat release rate modulations, fluctuating at f 0 , the forcing frequency, or at f 0 /2 due to a vortex pairing phenomenon; flame blowout induced by the competition between vertical and lateral displacements due to the induced axial and transverse acoustic velocities, respectively.Published by Elsevier Masson SAS on behalf of Académie des sciences.