Diesel Spray Analysis by Means of Planar Laser-Induced Exciplex Fluorescence

Abstract

The planar laser-induced exciplex fluorescence (PLIEF) technique has been used to visualize and measure the fuel/air concentration fields in both liquid and vapour phases of direct injection (DI) diesel sprays. Experiments have been performed in a hot rig, which provides a thermodynamic environment realistic for current DI diesel engines, using a blend of 90 per cent hexadecane, 9 per cent α-methyl-naphthalene, and 1 per cent N,N,N',N'-tetramethyl- p-phenylenediamine to separate spectrally the fluorescence signal from the liquid and vapour phases of the diesel. In this paper, measurements have been performed for three injection pressures and three combustion chamber density values. The results on penetration and fuel concentration in liquid and vapour phases are analysed, providing evidence of the similarities between diesel sprays and gaseous turbulent jets.