Optisk undersökning av dieselsprayer från en höghastighetsroterande insprutare
There have been changes in Earth?s climate system on both global and regional scale since the pre-industrial era and some of these changes are due to human activities such as the combustion of fossil fuels. This calls for the development of engines with a higher efficiency and less harmful emissions. One interesting concept is the Homogeneous Charge Compression Ignition (HCCI) engine, which has the advantages of potentially low emissions combined with high efficiency. However, HCCI with diesel fuel requires a relatively long fuel/air mixing time to ensure a "homogenous" charge. This requires advanced injection timing. Regular common rail injectors have not been successful at this task, due to fuel wall impingement.The High Speed Rotating Injector (HSRI) is an experimental injector aiming at shortening the spray penetration length and creating a more homogeneous charge by means of rotating the injector around its axis. This thesis explains the experimental setup and problem solving process for the HSRI and the results from experiments in the spray visualization apparatus.During the experiments in the spray visualization apparatus, two views of the sprays were used, side view and bottom view. The bottom view experiments showed that rotating the injector gave a decrease in spray penetration as a result of an increase in rotational speed. However, the static injector gave a shorter penetration than the rotating ones during the initial stage and later increased to produce the longest penetration. One hypothesis that could explain this phenomenon is that the increased rotation causes less cavitations in the sac, which decreases the cavitation-induced turbulence. With the somewhat crude calculations in mind, rotating the injector gave an increase in spray cone angle as a result of an increase in rotational speed. However, the same phenomenon as with the penetration was seen, namely that the static injector deviated and gave a larger cone angle than the rotating ones during the initial stage and later decreased to become the smallest cone angle. The side view experiments showed that rotating the injector does not change the side view cone angle, only shortens the penetration. With the same penetration, an increase in the bottom view cone angle also translates into an increase in volume, since the side view cone angle does not change.