Direct numerical simulation of flame stabilization downstream of a transverse fuel jet in cross-flow

Abstract

A reactive transverse fuel jet in cross-flow (JICF) configuration is studied using three-dimensional direct numerical simulation (DNS) with detailed chemical kinetics in order to investigate the mechanism of flame stabilization in the near field of a fuel jet nozzle. JICF configurations are used in practical applications where high mixing rates are desirable between the jet and the cross-flow fluids such as fuel injection nozzles and dilution holes in gas turbine combustors. This study examines a nitrogen-diluted hydrogen transverse jet exiting a square nozzle perpendicularly into a cross-flow of heated air. Improved understanding of the flame stabilization mechanism acting downstream of the transverse fuel jet will enable the formulation of more reliable guidelines for design of fuel injection nozzles which promote intrinsic flashback safety by reducing the likelihood of the flame anchoring at the injection site. The core of the heat release is located near the trailing edge of the fuel jet, at approximately 4 nozzle diameters away from the wall, and is characterized by the simultaneous occurrence of locally stoichiometric reactants and low flow velocities in the mean. The location where the most upstream tendrils of the flame are found is in the region where coherent vortical structures originating from the jet shear layer interaction are present. Instantaneously, upstream flame movement is observed through propagation into the outer layers of jet vortices.