Experimental and Numerical Investigation of Premixed Flame Quenching in Rotating Vessels

Among the various systems suitable for flame stabilization, the swirling of the flow in the combustion chamber is widely adopted in practical combustors. This work focuses into premixed combustion where swirling is used both to enhance perfect mixing of reactants and to guarantee sufficiently large residence times of the burning gases in the combustor for flame stability [1]. Despite the practical importance of this flame configuration, a full understanding of the flame behaviour under conditions of rotating flow is not achieved [2]. Previous investigations of flames propagating in predominantly whirling flow have shown many interesting problems, like a very fast flame propagation along the axis of rotation [3], enlarged flammability limits [4], but also a strong quenching effect under the action of centrifugal forces [4]. All these aspects have great implications on the combustor design but also on the understanding of the flame propagation mechanisms. Several experimental investigations have been conducted at Lodz University of Technology on a purely rotating flow configuration with the aim to isolate the effect of centrifugal forces [2,4]. By observing the flame propagating in perfectly premixed mixture inside a rotating vessel, the effect of several parameters, as the mixture composition, the rotation rate, vessel geometry and size, have been determined. However, the observed flame behaviour have revealed that the flow structure can exhibit a very complex evolution that is very difficult to reveal with experimental diagnostic tools. Therefore a program for the numerical simulation of the experimental setup has been started. The simulation results have confirmed the presence of a complex flow and furnishes a detailed picture of all the variables required for further analysis and identification of the quenching mechanism.