Ambient pressure effects on the near burner structure of gas jet flames in crossflow

Abstract

Flame structure and geometry of natural gas and propane diftusion flames in cross flow are presented to delineate the effects of buoyancy and ambient pressure. The fuel was injected horizontally into a vertically Imoving air stream. The buoyancy acted along the direction of the cross-flow. The combustion chamber pressure was varied from 1 bar to 1.45 bar and the cross-flow to jet velocity ratio from 0.1 to 1.45. Quantitative Rainbow Schlieren Deflectometry (RSD) was used to visualize flame and to measure the geometrical parameters. It was found that the centerline flame trajectory showed three distinct regions and the dimensionless coordinate of the jet centerline in the jet direction varied with 0.45. 0.25, 0 power of the coordinate in the cross-flow direction and -0.5 power of the Froude number based on the jet velocity. The flame trajectories did not change significantly with pressure. Flame chord length varied with 0.45 power of the cross-flow/jet velocity ratio. Flame length and soot formation characteristics changed notably with pressure. Propane flame was more susceptible to the ambient pressure. The flame luminosity due to soot in the propane flame changed only slightly with velocity ratio. However, natural gas flame became nonsooty at high velocity ratios.