The problem of fuel injection has always been in the centre of new technological developments. The technical and economical requirements include decreasing formation of pollutants in emission and economical consumption with optimal reliability and performance. A great progress in this area has been obtained by the introduction of the Common-Rail-Systems and pump-injectors in the past two decades. Both methods use the advantages of high injection pressure. Parallel to further developments of efficient and conventional injection methods the new injection strategies are development.One possible approach to solve this problem is the optimization of injection strategy by employment of Laval or coaxial nozzles (one example of Laval nozzle is shown in Fig. 1). The atomization process in such nozzles occurs by fragmentation between high velocity gas jet and fuel volume.
Fig. 1: Scetch of Laval nozzle
Fig. 2: Extension of cavitation within the nozzle and the associated spray formation