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The enhancement of vortex development, fuel-air mixing and heat release in diesel spray flame by inversed-delta injection rate shaping, having been predicted via LES simulation with detailed chemical kinetics, is experimentally confirmed for the first time. Newly developed 3-injector TAIZAC (TAndem Injector Zapping ACtivation) injector realizing aggressive inversed-delta injection rate shaping was used for single-shot combustion experiments in a constant volume combustion vessel. Simultaneous high-speed (120,000fps) and high-resolution (1,280 x 704 pixels) laser schlieren and UV OH* chemiluminescence imaging combined with subsequent Flame Imaging Velocimetry (FIV) analysis was employed to elucidate the correlation between vortex development and enhanced heat release.

As a new method to examine the extremely unsteady and spatially varying wall heat transfer phenomena on diesel engine combustion chamber wall, high-speed imaging of infrared thermal radiation from the chromium coated window surface impinged by a diesel spray flame has been conducted in a constant volume combustion chamber. The infrared radiation from a back surface of the chromium layer was successfully visualized at 10kHz frame rate and 128 × 128 pixel resolution through the window. The distributions of infrared radiation, temperature and heat flux exhibited coherent and streaky structure with radial stripes extending and waving from a stagnation point likely reflecting the near-wall turbulent structure in a wall impinging diesel flame. The experiments were conducted with various parameters such as fuel injection pressure, ambient gas oxygen concentration, wall impinging distance, wall surface roughness and wall materials.