It has been widely reported that split injection in engines can increase fuel/air mixing and reduce the formation of unburned products of combustion. Large-eddy simulations (LES) of pulsed jets are carried out to understand the mechanism of mixing. The results indicate that in a double injection event, i.e., an injection event with two pulses, an earlier transition and breakup of the head-vortex region in the second pulse occurs as a result of the residual turbulence from the first pulse and reduced rotational strength of the head vortex. The simulations also predict that there is potentially a balance between the effects of the residual bulk velocity to accelerate the second pulse and the effects of the earlier breakup of the head-vortex region to reduce penetration in the second pulse. Depending on the dwell time between the pulses, one or the other of these effects may be dominant. The computed results show faster spreading and slower penetration of the second pulse, relative to the first pulse, once the head vortex interacts with the turbulent eddies remaining from the first injection. The results are related to observed split injection behavior in engines.
|Titolo:||Mixing Mechanism of Pulsed Jets with Applications to Fuel Delivery in Combustion Applications|
|Data di pubblicazione:||2012|
|Appare nelle tipologie:||4.1 Contributo in atti di Convegno|