Spray Combustion Modeling in Lean Direct Injection Combustors, Part I: Single-Element LDI

Abstract

Lean direct injection (LDI) is one of the most promising low NO_x combustion concepts for aero-engines. This work reports turbulent reacting spray modeling in a single-element LDI combustor to determine a validated numerical framework that can be used to model such complex combustion systems involving highly swirling flows, droplet breakup, and combustion. Different sub-models are employed within a numerical framework to characterize the spray processes involved in the primary atomization and secondary breakup regimes. The sensitivity of the associated breakup model parameters to the predicted behavior is investigated, thereby fine tuning the sub-models for turbulent spray combustion in LDI. The two-way coupling accomplishes the interactions between the liquid and gas phases and the respective phase properties are analyzed. The size and distribution of drops are computed at various locations and the results are compared with the measurements. The work demonstrates that modeling of primary atomization improves the overall predictions of both gas phase and spray. The validation with the measurements reflects that the numerical framework implemented in this study is able to characterize the effects of highly swirling flows with strong turbulence on spray velocity and size distribution, and strong momentum exchange between the gas and liquid phases.

Keywords:

• Aeroengines
• Drop breakup
• Lean direct injection
• Spray combustion
• Turbulent dispersion