Current Technological Advances in Fuel Spray Imaging

Energy remains one of the most important factors in both the global economy and ecology. Currently, there is a strong focus on the development of renewable energies. This is a laudable goal; however, every second of every day sees 10,000 gallons of petroleum burned in the United States. Combustion is now and will remain a predominant share of the world's energy usage; the efficiency of combustion engines must be maximized. The cornerstone of engine efficiency lies in the fuel spray; more information on the fluid dynamics associated with spray breakup and atomization is certain to lead to increased combustion efficiency. This paper will discuss one of the most promising emerging technologies in fuel spray imaging - an ultrafast laser based technique known as ballistic imaging. Ballistic imaging, initially developed in the medical field, has provided the first high resolution images of both the liquid core and the primary breakup processes of a variety of atomizing fuel sprays. Transient ballistic imaging diagnostics have been used to reveal details of the primary breakup process in a LOX injector, a turbulent water jet, a water jet in cross-flow, a transient diesel fuel spray, a rocket fuel injector, and an aerated spray. This leading edge research project is currently underway at Chalmers University of Technology in Gothenberg, Sweden as well as a variety of research institutions and universities worldwide. The results provided by this relatively new imaging technique have been used by combustion engine modelers in their quest to design more efficient and cleaner combustion engines.