Experimental and Computational Investigation of a Reed-Valved Propane-Fueled Resonant Pulse Combustor

A small-scale Resonant Pulse Combustor (RPC), utilizing a passive reed-type air valve, was successfully converted from its original gasoline to gaseous propane fueled operation. The conversion was initiated as a precursor to testing the same RPC unit fitted with a novel active rotary air valve designed in 2024. The optimal rotary valve motion profile was determined using computational fluid dynamic (CFD) simulations. The simulations used propane fuel in order to avoid the complexities associated with liquid fuel jet breakup, atomization, and evaporation. However, it was not known whether an RPC of this scale would actually operate on propane and/or whether fuel injection strategies would require alteration when switching from liquid to gaseous fuel. Therefore, it was prudent to attempt a conversion of the existing reed valved unit, and if successful, to compare the experiment to CFD simulations of the same. Results show that propane operation is possible, that performance is enhanced slightly, and that throttling range is increased. The experiment was found to be very sensitive to the axial location of fuel injection. Comparison with simulations showed reasonable agreement on performance, but the simulations show much less sensitivity to injection location, and a larger throttling range. This disparity is attributed to the axisymmetric assumption of the simulations versus the discrete injection jets of the experiment. A second contributing factor is likely the initiation process of the simulations compared with the actual starting process of the experiment.