A Numerical Investigation of Non-Evaporating and Evaporating Diesel Sprays

Fuel injection characteristics, in particular the atomization and penetration of the fuel droplets, are known to affect emission and particulate formation in diesel engines. It is also well established that the primary atomization process is induced by aerodynamics in the near nozzle region, as well as cavitation and turbulence from the injector nozzle. However, most breakup models used to simulate the primary breakup process in diesel engines only consider the aerodynamically induced breakup. In this paper, the standard breakup models in Diesel Engine modeling code called “CONVERGE” are examined in constant volume spray chamber geometry using the available spray data. Since non-evaporating sprays provide a more stringent test for spray models, the x-ray data from Advanced Photon Source is used for detailed validation of the primary breakup model, especially in the region very close to the nozzle. Extensive validation of the spray models is performed under evaporating conditions using liquid length and spray penetration data. Good agreement is observed for global spray characteristics. However, the breakup model could not reproduce some of the experimental trends reported in literature thus identifying the need for a more comprehensive primary breakup model. An attempt is made to statically couple the internal nozzle flow with spray simulations, and examine the effect of nozzle orifice geometry on spray penetration.