Computational fluid dynamics analysis of flow and combustion of a TIER IV emissions standard diesel engine

In this study, flow and combustion characteristics of a TIER IV emissions standard diesel engine is investigated using Computational Fluid Dynamics (CFD). Gas exchange calculations are done using AVL Boost program in order to obtain performance characteristics of the engine. Whole engine components are modeled and analyses are performed for all engine speeds. Calculated crank angle dependent pressure and temperature values are used as boundary condition for reactive 3D CFD simulations. The effect of intake manifold geometry on in-cylinder air motion is analyzed carrying out 3D turbulent flow computations using Star-CCM+. Simulations are conducted under steady-state and isothermal conditions for different valve lifts. Swirl number is calculated and compared with available experimental results. Reactive CFD simulations are performed with 45° sector geometry for the period that both valves are closed. Additionally, reactive simulations including ports, moving valves and piston are carried out for full engine model (360°). In reactive simulations, RNG k-ε and ECFM-3Z models are used to characterize turbulence flow field and combustion respectively. A lagrangian approach is used for two-phase flow computations to simulate the liquid fuel injection. Commercially available CFD code STAR-CD and its sub-module es-ICE are used for three dimensional reactive simulations, moving grid generation and problem setup. Predicted in-cylinder pressure and apparent heat release rate are validated with experimental results. NOx and Soot formations as a result of combustion process are also investigated. Keywords: Computational fluid dynamics, Internal combustion engines, Lagrangian two phase modeling, Combustion, Emissions