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

Abstract

The Engine Combustion Network (ECN) provides useful database for diesel spray and combustion characteristics in a simple setup of a constant volume chamber. In this work 3D simulation is performed to evaluate the models of 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 a Lagrangian format. The CMC model is implemented in the open source code, OpenFOAM, to provide conditional flame structures through the Eulerian as well as the Lagrangian conditional transport equations. Predicted ignition delays and lift off lengths are validated against measurements in the ECN. The convection term is differenced in first order and second order upwind schemes in the Eulerian CMC transport equations for species mass fraction and enthalpy. Simulation has been performed in different oxygen concentrations and ambient temperatures. Results show better prediction of ignition delays and lift off lengths due to better treatment of the convective term in Eulerian CMC than in Lagrangian CMC.