Numerical simulation of liquid fuel prechamber ignition

Abstract

A Computational Fluid Dynamics (CFD) model was built that simulates the transient, compressible, reacting, multi-phase environment that exists within a reciprocating engine's combustion chamber(s). ANSYS Fluent v13.0 was used with the Euler-Lagrangian Discrete Phase Model (DPM), the Shell autoignition model, and the Large Eddy Simulation (LES) method of turbulence modeling. Validation of the spray dynamics was performed by comparing simulation results with experiments of liquid and vapour penetration length of an n-Heptane spray experiment done by Sandia National Laboratories. It was found that LES produced more accurate results than several Reynolds Averaged Navier-Stokes (RANS) models. The Shell autoignition model was coded to function with C10.17H19.91 and compared with experimental ignition results in a Rapid Compression Machine (RCM) environment. All of the above models were then combined to simulate a directly-fueled lean-burn combustion prechamber configuration wherein the effects of spray angle, timing, and duration were studied.