Transient response of the Delft jet-in-hot coflow flames

The role of temperature, mixture fraction, and scalar dissipation rate on transient methane injection and auto-ignition in a jet in hot coflow burner

“…Furthermore, the residence time of an igniting mixture pocket can be expected to be larger in this region. Such regions can be observed at z > 34 mm at t = 2.2 ms. A transition from an initial laminar phase to a turbulent phase, as observed by Oldenhof et al [17] in a similar configuration at lower jet Reynolds numbers was not observed in the current experiment. damage from reflections of the low-intensity wings of the lasersheet off the fuel nozzle.…”

“…It was found that the ignition frequency was dependent on the nitrogen mole fraction in the jet. Oldenhof et al [17] studied the ignition of impulsively-started natural gas jets issuing into a hot vitiated coflow. Initially, a laminar flow phase was observed, followed by a rapid transition to a turbulent phase after a few milliseconds.…”

“…Gordon et al [15] observed isolated ignition kernels corresponding to a rise of temperature and CH 2 O concentration; however, OH was not present in all ignition kernels, indicating auto-ignition (and not flame propagation) is a primary mechanism behind lifted flame stabilization. With the recent development of high-speed laser measurement and imaging techniques [19][20][21] , new insights into the mechanisms governing auto-ignition has been gained in transient systems [17,[22][23][24][25][26][27][28][29][30][31] . In the current work, high-speed laser-based measurements are used to reveal details of the roles of temperature, mixture fraction, and scalar dissipation rate on auto-ignition within a JHC configuration.…”

Simulations of laminar non-premixed flames of kerosene with hot combustion products as oxidiser

“…These investigations add insight to experimental studies that define MILD combustion through oxidiser oxygen content and preheat temperature, such as those performed with a jet in hot and diluted co-flow [11,[16][17][18][19][20] or cross-flow [21], although many have focused on the effect of hot combustion products from a premixed flame near stoichiometry [12] or inert diluent [3,14] at an externally fixed temperature, mixed in known proportion with fresh oxidiser or fuel. Recently, an effort has been made to extend this work to combustion systems with internal recirculation or staged combustion processes, in which the hot combustion product temperature and composition are connected and controlled by the near-or fullyadiabatic mixing of hot products with oxidiser in a counterflow configuration [5,6].…”

Modeling Lifted Jet Flames in a Heated Coflow Using an Optimized Eddy Dissipation Concept Model

“…The 4.6 mm diameter central jet of the JHC burner, issues into an 82 mm diameter concentric coflow of combustion products from an up-stream secondary burner. The JHC burner has been used to provide experimental data for numerous fuel and Reynolds number combinations (Dally et al, 2002;Medwell et al, 2007Medwell et al, , 2008Medwell & Dally, 2012;Oldenhof et al, 2010Oldenhof et al, , 2011Oldenhof et al, , 2012, as has the similarly configured Vitiated Coflow Burner (VCB) (Cabra et al, 2002(Cabra et al, , 2005Gordon et al, 2008).…”