In recent years there has been an increasing awareness of the environmental effects, which has led to stringent emission regulations on automotive engines. Fulfilling restriction levels of emission has become one of the most significant challenges for engine designers. The nature of the combustion process is driven by the quality of the fuel spray, its distribution and mixing within the combustion chamber. Processes such as atomization, droplet distribution, and ignition have a direct influence on the combustion performance and emission characteristics.

An in-house built, optically accessible, high-pressure, and high-temperature combustion vessel is used to investigate the fuel spray characteristics and combustion details. With a maximum pressure of 100 bar, a maximum temperature of 1000K, and an air flow rate of 60 m3/h, single component fuels, multi component mixtures, commercial fuels, and bio-fuels are investigated under engine like conditions. The experimental results are utilized to establish better understanding of the spray atomization and mixing process based on the fuel’s physical properties, injector types and nozzle geometry. Non-combustion spray characteristics such as penetration length and cone angle, in both liquid and vapor phases, are determined by conducting Diffuse Backlight Illumination (DBI), Mie-Scattering, Schlieren and Shadowgraphy techniques. Combustion studies such as flame lift-off length and ignition delay are determined by OH* chemiluminescence (OH*). Soot volume fraction (fv) is studied by Saturated Planar Laser Induced Incandescence (SPLII) combined with Laser Extinction (LE) techniques and soot mass by DBI.