Browse Publications Technical Papers 2010-01-1133
2010-04-12

Large Eddy Simulation of a Transient Air Jet with Emphasis on Entrainment during Deceleration 2010-01-1133

Recent experiments of diesel injection processes have demonstrated that mixing accelerates after the end of injection (EOI). This finding has significant implications for low-temperature combustion (LTC) diesel engines. Previous simulations using a one-dimensional model of a single-pulsed air jet, which is analogous in many aspects to diesel jets, suggest that the rapid mixing after EOI in diesel jets is due to a temporary increase in the entrainment rate as the jet decelerates. In the present study, we performed a high-fidelity large eddy simulation (LES) of an unsteady air jet identical to that used for the one-dimensional model. The LES calculation agrees well with available experimental data and provides both spatially and temporally resolved details of the three-dimensional transient mixing field. Results show that entrainment increases during deceleration. We propose that the enhanced entrainment is due to the growth of the interface between the turbulent jet flow field and the non-turbulent ambient field, and that the growth of this interface is a consequence of the enhanced flow instability that is induced by the deceleration of the jet.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X