Interaction Behavior of Pulsejet Engines

Valveless pulsejet engines are analyzed as electric circuits in which the main engine components (inlet, combustion chamber, and tailpipe) are assigned impedance values and represented using a system of linear equations. The solution to these equations yields Bode plots for the engines that can be used to predict operating frequency as well as the effects of individual component dimensions on overall engine behavior. This method of analysis is found to predict engine operating frequencies to within 7% of experimentally measured values. The analysis is extended to include systems of multiple engines and again verified by comparison to experiment. It is shown that multiple engines can be locked in phase or in antiphase predictably by selecting the proper interconnection method. The latter has important implications for noise reduction and for propulsion applications involving arrays of pulsejets.