Numerical Simulation of Diesel Spray Combustion in a Constant Volume Chamber by Eulerian and Lagrangian Conditional Moment Closure Models

The Engine Combustion Network (ECN) [1] provides useful database for n-heptane spray combustion in a simple setup of a constant volume chamber. In this work 3D simulation is performed to evaluate the models for spray development, ignition and turbulent combustion for the ECN test cases. The conditional moment closure (CMC) model has successfully been applied in diesel engines with single and multiple flame structures in the Lagrangian framework. Here the CMC model is implemented in the open source code, OpenFOAM [2], to provide conditional flame structures through solution of Eulerian as well as Lagrangian conditional transport equations. Simulation is performed in different oxygen concentrations and ambient temperatures with predicted ignition delays and lift-off lengths in good agreement with measurements. Both Eulerian and Lagrangian CMC show similar results, although Eulerian CMC involves more accurate treatment of the conditional convection term.