Dynamic Characterization of a Laboratory-Scale Pulse Combustor

Abstract

Pulse combustion is a self-sustained and self-oscillating process driven by combustion, coupled with resonant oscillation of the flow in the tailpipe. This article describes the investigation of the effects of different parameters in a laboratory-scale pulse combustor and analyzes them using concepts of nonlinear dynamics. Two orientations of the fuel injection holes were used. In one orientation, the fuel comes in vertically in parallel and counter-flow with the air stream, while in the other orientation the fuel is injected horizontally at cross-flow with the air stream. For the vertical orientation, the frequency slightly decreased with decrease of global equivalence ratio and inlet flow rate. With change of lean to rich air/fuel mixture, the dynamics changes from non-pulsating to pulsating combustion. The transition from noise-dominated to periodic oscillation has also been verified by evaluating the correlation dimension. In the horizontal orientation of the fuel inlet, the pulsating behavior has been obtained even under fuel-lean conditions due to better mixing of air and fuel, and phase and fast Fourier transform plots indicate quasi-periodic behavior.