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An experimental study of real multi-hole diesel nozzles with different geometry in terms of conicity factor has been performed under current DI Diesel engines operating conditions. A complete characterization of the internal nozzle flow and the sprays injected under non-evaporative conditions has been performed. The results of that study are applied in order to assist the analysis of spray in evaporative conditions. In this case, results of liquid-phase fuel penetration were obtained from a wide optical access engine operating under non-reacting conditions. From these measurements, a comparison of the results with a theoretical Diesel spray model in evaporative conditions has been carried out. This comparison has allowed the determination of the dependence of stabilized liquid length on injection pressure, ambient conditions and nozzle geometry.

Starting and operating of diesel engines in cold conditions is a common and important problem. Many factors such as ambient conditions, fuel properties, fuel injection, cranking speed, etc, affect cold engine functionality. In order to improve diesel engine cold start, it is essential to understand better these problems. In this paper the injection development at cold temperatures is studied, since it is an important parameter that affects the fuel interaction with the air, so the future combustion process would also be influenced. In particular, a hydraulic characterization of diesel injection is made, using specialized test rigs that simulate real engine in-cylinder air pressure and density; the fuel is injected from three axi-symmetric convergent nozzles at several injection pressures (30, 50, 80, 120 and 180 MPa), two chamber densities and two temperatures of 255 K (winter) and 298 K (reference).