Modeling of a self-excited pulse combustor and stability analysis

Abstract

The major bottleneck for popularization and utilization of the conventional mechanical valve pulse combustors is the self-priming mode of gas supply. An aerodynamic valve (as against mechanical valve) self-excited pulse combustor of the Helmholtz-type with continuous supply of gas and air was designed and a mathematical model was established in this paper. The theoretical model employed well-stirred reactor model and a single step Arrhenius chemistry, and took those factors which might affect the combustion stability into account. The factors include the variation of the mass rate of the reactants affected by the pressure in the combustion chamber, the convective and radiation heat loss in the combustion chamber, and the heat transfer and wall friction in the tailpipe. The effect of wall temperature of combustion chamber, wall heat transfer coefficient, tailpipe length and friction coefficient on combustionstability were analyzed. The range of combustion oscillations can be predicted. It is theoretically and experimentally shown that combustion oscillations can be produced with a continuous supply of fuel and air without mechanical valves. The experimental data show qualitative agreement with predictions from the theoretical model. The theoretical model could be a tool for designing and optimizing the self-excited pulse combustor.