Numerical Simulation of Premixed Flame Quenching in the Broken-Reaction-Zone Regime

摘要: Lean perfectly premixed ∞ame propagation in a swirling ∞ow dump combustor is studied. The emphasis on the Broken Reaction-Zone (BRZ), where reaction zone thickness (‐F) larger than Kolmogorov scale (·). Linear-Eddy Mixing (LEM) model used to simulate subgrid interactions between structure and unresolved turbulent structures within framework of large-eddy simulation (LES) approach. A real case scenario studied: lean combustion chamber heat losses at walls are taken into account via use simple loss model. Results show lift-ofi, caused by quenching, for low equivalence ratio ('=0.45). dynamics subsequent can be linked natural dynamics. frequency lift ofi equal half-flrst longitudinal oscillation mode. Since early 90’s, gas turbine based ground power generation considered an environmentally-friendly alternative more polluting coal-burning plants. As large investments made transport distribute liquid form (Liquid Natural Gas, a.k.a. LNG), number plants that will enter service soar next few decades. Independently development LNG technologies, gasifled coal (syngas) also as possible fuel plants, even though syngas less energy-dense gas. These state-of-the-art turbines Lean-Premix-Prevaporized (LPP) technology operated only slightly higher extinction limit. Although it often assumed process taking place these ∞amelet regime, ‐F ·, chemical time (?C) smaller characteristic (?F), other regimes locally present. In regions high turbulence, smallest eddies thickness. this case, penetrate preheat zone, increase species transport, Furthermore, experiments 1{3 have shown very level turbulence result stabilized exhibit local (quenching small portion ∞ame) without global creating hole unburnt reactants product region). Both quenching not fully understood. theory, direct action and/or powerful enough break-up but has never been formally demonstrated, neither nor numerical simulations. Other factors such distribution, geometry, losses, etc., all when This work focuses investigation lean, swirl ∞ames with objective study phenomena its impact overall process.