The work presented in this paper is part of an investigation into the operating characteristics of natural gas fired, valved, Helmholtz type, pulse combustors. This article presents some experimental results that describes the controlling mechanisms which control the existence of a rich limit of operation of the pulse combustor. Acoustic pressure oscillations and the global heat release rates were measured to determine how they and their correlation determine the performance of the pulse combustor. Experimental results indicate that the combustion induced driving force near the lean limit is barely larger than the damping of the system. This is due to the relatively large phase difference between the heat release and pressure oscillations under these operating conditions. Near the rich limit (i.e., near .phi.=1), on the other hand, pressure and heat release fluctuations are nearly in phase. Therefore, the driving force is relatively high. Nevertheless, a rich limit of operation is reached. The investigation has shown that this limit is reached because when operating near the stoichiometric ratio, the rapidly entering air jet quenches the ignition source (i.e. reacting gas pockets) left over from the previous cycle.
Relation:
中華民國第四屆燃燒科技應用研討會論文集=Proceedings of the Fourth National Conference on Combustion Science and; Technology, pp.1-5
