End-to-end modeling of fuel injection via static coupling of internal flow and ensuing spray

Abstract

Accurate knowledge of fuel spray behavior is of utmost importance for liquid-fuel-based combustion systems. Fuel properties, injector geometry, operating conditions, and thermal state of the combustion chamber determine the fuel’s ability to mix and burn efficiently. Three-dimensional computational-fluid-dynamics models can reveal the complex dynamics of the injector’s internal flow, as well as the spray breakup, evaporation, mixing, and combustion. However, time and length scales of in-nozzle flow and ensuing spray can differ by several orders of magnitude, limiting the feasibility of a simultaneous solution of the entire chain of physics. This work explores an end-to-end approach to decouple the problem at the injector outlet via a static-coupling framework. Flowfields are sampled at the injector exit, stored into spatiotemporally resolved maps, and used to initialize a Lagrangian spray whose properties reflect the flow’s instantaneous state as predicted by the in-nozzle flow simulations. Comparisons against typical rate-of-injection results and qualitative validation against optical spray data highlighted the ability of static coupling to unveil spray physics that would otherwise be missed.

In-cylinder spray evolution in a motored central-injection gasoline engine: Imaging and simulating the effects of flash-boiling and intake crossflow

“…It is noted that the KH-RT model is meant to describe the mechanical and aerodynamic instabilities of liquid jets, and, in principle, cannot represent the flash-boiling-induced atomization mechanism. Nevertheless, this breakup model (as well as the other spray submodels mentioned above) is commonly and widely used to model spray breakup in ICE applications under many conditions, [39][40][41][42] often without recognizing its applicability limits. Hence, one of the goals of this study is to assess the KH-RT model performance when dealing with flash boiling sprays.…”