An experimental study of the ignition and combustion mechanisms in a pulse combustor. Characteristics of a valveless pulse combustor.

The possibility of realizing a wide range, low noise valveless pulse combustor is examined by charging a rich propane-air mixture having an equivalence ratio of 3.0 with a relatively high supply pressure of 0.5-35 kPa under the condition of forced ventilation. The utilization of the backer plate as a baffle plate is found to act effectively, not only on the strong mixing of fresh inflows and residual hot combustion products, but also on the prevention of back flow during an explosion period, provided that the clearance between the nozzle exit and the baffle plate is adjusted to the optimum. The results show that the present valveless pulse combustor operates more silently than the flapper-valved pulse combustor by 5-8 dB(A), having a large turn down ratio of 9.5-11.5. Also, the volumetric efficiency of the pulse combustor varies from 3 to 8 %, the range being nearly the same as that of the flapper-valved pulse combustor.