Structure of high-pressure diesel sprays

A comprehensive set of computational and experimental results for high- pressure diesel sprays are presented and discussed. The test cases investigated include injection of diesel into air under both atmospheric and high pressure/temperature chamber conditions, injection against pressurized and cross-flowing CF6 simulating respectively the density and flow conditions of a diesel engine at the time of injection, as well as injection into the piston bowl of both research and production turbocharged high-speed DI diesel engines. A variety of high-pressure injection systems and injector nozzles have been used including mechanical and electronic high-pressure pumps as well as common-rail systems connected to nozzles incorporating a varying number of holes with diameters ranging from conventional to micro-size. Results from spray imaging, phase doppler anemometry and CFD calculations of both the internal nozzle flow and the subsequent spray development have been combined to identify the relative importance of the geometric/operating parameters that control the structure of diesel sprays and areas of further research.