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

Abstract

a b s t r a c tThe transient injection and subsequent auto-ignition of a methane jet issuing into a laminar coflow of hot exhaust gas from a lean premixed hydrogen air flame was studied using high-speed planar Rayleigh scattering, yielding two-dimensional measurements of mixture fraction, temperature and scalar dissipation rate with high spatio-temporal resolution. The temporal development of the mixing field between the transient fuel jet and the surrounding coflow prior to the occurrence of auto-ignition was examined at a sampling rate of 10 kHz. The impact of the transient jet development on numerical modeling of this test case is discussed. It was found that auto-ignition occurred after the jet transitioned from a transient state into the steady state, thus eliminating the need to model the complete transient fuel injection when the primary focus is on the onset of auto-ignition.Simultaneous high-speed OH * chemiluminescence from two viewing angles was applied to gain 3D-information of the ignition kernel location. This information allowed the selection and analysis of ignition events where the initial kernel formed inside the laser light sheet. Detailed analysis of the dynamics of a single ignition event, as well as statistical analysis of multiple ignition events based on a joint probability density approach, indicated that the ignition kernels occurred at very lean mixture fractions and at locations with low scalar dissipation rates.

Experimental investigation of the auto-ignition of a transient propane Jet-in-Hot-Coflow

“…Both the DLR Jet-in-Hot-Coflow Burner (DLR JHC) [11,15,19,21] and the Rayleigh measurement setup [11] have been described previously, so only the key parameters are provided here.…”

“…The post-processing and measurement errors of the OH* CL images are discussed in [15,19,21] and are not explained here in detail. For the present study the OH* CL images were used for statistical evaluation of the influence of the coflow temperature on ignition time and location and to determine events where the initial auto-ignition occurred within the laser-sheet for the Rayleigh measurements.…”

“…The occurrence of auto-ignition at very lean mixture fractions complicates experimental investigations. For example, Papageorge et al [11] and Arndt et al [19] employed laser Rayleigh scattering for the simultaneous measurement of mixture fraction and mixture temperature immediately before the onset of auto-ignition in the DLR Jet-in-Hot-Coflow burner (DLR JHC). Due to the low fuel (in that case methane) content at auto-ignition sites and limited signal-to-noise ratio in the hot coflow, resolving the most reactive mixture fraction was not possible.…”

The Analysis and Research for the Plate Differential Oxygen Gas Sensor of Auto Based on the Temperature Field and Thermal Stress Field

“…By 2014, it reached 154 million vehicles, and by May 2015, it had more than 162 million vehicles [21]. Since 2010, the average annual growth rate of car ownership in the country has exceeded 15% [1][2][3].A large number of cars provide convenience for people's life. At the same time, it also brings many negative effects, such as traffic accidents, energy consumption, exhaust gas and noise pollution.…”

“…Heat conduction refers to the heat exchange behavior between two objects that are in contact with each other or between different parts of the same object due to the difference in temperature. Heat conduction follows the Fourier law: (2) In the formula, q'' is the density of heat flux and k is the thermal conductivity. The negative sign indicates that the heat is transferred in the direction of low temperature.…”