It is well established that the combustion development and the consequent pollutant emissions in a Diesel engine depend on the fuel spray characteristics. Nowadays, many new injection strategies are being tested, in order to improve the diesel combustion efficiency and so to reduce its environmental impact in terms of pollutant emissions and fuel consumption. Many works have proved that NOx, THC, CO and particulate levels emitted from a Diesel engine, as well as specific fuel consumption, depend, for a given engine speed and load, upon the parameters characterizing any particular injection strategy. Despite the extensive experimental activity analyzing the effects of the previous control parameters on the engine emission and fuel consumption levels, very few are the works dealing with the effect of the same parameters on the fuel spray, and in particular on the droplet dimension distribution.
The aim of this work is therefore to study these effect. A diesel injector was mounted inside a chamber and the spray was characterized in terms of droplet dimension using the Malvern laser technique, when a double injection was tested setting different values for the injection pressure, injection duration and dwell between consecutive injections.