Characterization of Periodic, Quasiperiodic, and Chaotic States in Nonpremixed Biodiesel/Air Jet Flames

Characterization for nonpremixed biodiesel/air jet flames instability is investigated by the 0-1 test for chaos and recurrence plots. Test conditions involve biodiesel from Jatropha curcas. L-fueled flames have inlet oil pressure of 0.2–0.6 MPa, fuel flow rates (Q1) of 15–30 kg/h, and combustion air flow rate (Q2) of 150–750 m3/h. This method is based on image analysis and nonlinear dynamics. Structures of flame are analyzed using an image analysis technique to extract position series which are representative of the relative change in temperature of combustion chamber. Compared with the method of maximum Lyapunov exponent, the 0-1test succeeds in detecting the presence of regular and chaotic components in flame position series. Periodicand quasiperiodic characteristics are obtained by the Poincaré sections. A common characteristic of regularnonpremixed flame tip position series is detected by recurrence plots. Experimental results show that theseflame oscillations follow a route to chaos via periodic and quasiperiodic states