The influence of pressure on soot production and radiation in turbulent kerosine spray flames

Detailed measurements of mixture fraction, flame temperature, soot volume f raction and spectrally resolved thermal radiation are reported in turbulent kerosine spray flames, burning at elevated temperatures and pressures (up to 13 bar). Flames are supported on an internal mixing, air-assist injector and confined within a cylindrical pressure vessel. Contrasting results, ar ising from the analysis of data on kerosine spray flames burning at various operating pressures, air-fuel ratios and fuel how rates, are presented whi ch provide new insight into the influence of operating pressure on soot for mation and radiative heat transfer in practically relevant configurations. The experimental results between 1 and 13 bar suggest an underlying pressur e dependence of the soot chemistry which is broadly linear. In addition, ho wever, fuel atomisation and injector air-fuel ratio have a pronounced effec t on the sooting propensity of the spray flames, which can be stronger than the influence of the operating pressure itself. They have a particularly s trong influence on the rates of oxidative attack on soot particles and prec ursors and on the spectral distribution of thermal radiation between partic ulate and gaseous emissions. Continuum radiation from clouds of dispersed s oot particles in the flame provides the major contribution to the total fla me radiation in these comparatively fuel-rich kerosine spray flames with ga s band radiation proving of only minor importance. The total radiation inte nsity from the flame then closely mirrors the trend in soot formation rates with respect to the dependence on operating conditions.