Reactive Cfd in Engines with a New Unstructured Parallel Solver

M Zolver,O Laget,D Klahr,A Torres,J Bohbot

doi:10.2516/ogst:2003003

Abstract

KIFP, an hexahedral unstructured parallel code is currently developed at IFP since two years. Some algorithms of the KIVA-II's version currently used at IFP (KMB) are implemented in KIFP. Due to the new unstructured formalism, others algorithms (finite volume on staggered grid, time splitting, SIMPLE loop, sub-cycled advection, turbulent and spray models, etc. ) have to be modified. Some new ones, like the conditional temporal interpolation methodology for moving grids, the remapping algorithm for transfering quantities on different meshes during the computation, the Van Leer and Superbee' slope limiters for advective fluxes, Kay and Crawford's heat transfer model and ECFM gasoline combustion model have been added. Super-scalar machines being widely used and developed, KIFP has been optimised for running on this type of machine. Many computer platforms and compilers have been tested. Because of its low cost of implementation, the OPEN-MP standard paradigm is used to parallelize the code. A speed-up of 3 on 4 processors is reached. KIFP is now able to well simulate 3D combustion in actual automotive engines: as example, we show in this paper some computations of an helical port on a steady state bench, an intake/compression/combustion in a port fuel injection (PFI) spark ignited engine with a pent roof chamber and a compression/spray injection in a direct injection (DI) Diesel engine. Comparisons with experimental results for engine cases (rotation speed and swirl coefficient for the steady state simulation and mean pressure curves for unsteady ones) or with analytical results for academic test cases are done as much as possible.

Highlights

Understanding and developing new engine concepts require more and more help from 3D CFD and combustion modeling
KIFP is able to well simulate 3D combustion in actual automotive engines: as example, we show in this paper some computations of an helical port on a steady state bench, an intake/compression/combustion in a port fuel injection (PFI) spark ignited engine with a pent roof chamber and a compression/spray injection in a direct injection (DI) Diesel engine
The time integration done by KIFP is used to achieve the steady state at convergence

Summary

Introduction

Understanding and developing new engine concepts require more and more help from 3D CFD and combustion modeling. At IFP, for many years, a modified version of KIVA II (Amsden et al, 1989), called KMB (Habchi and Torres, 1992; Torres and Henriot, 1996), has been developed and used. Even if KMB is adapted to engine calculations (Henriot et al, 1999), there are strong constraints like the time taken by structured grid generation in complex geometries or the exclusive use of very expensive vector computers. Bad shaped cells and corner cells in complex geometry may limit the numerical accuracy and highly increase the CPU time. To avoid those problems, it has been decided to develop a new hexahedral unstructured version of KMB, which is called KIFP, dedicated to parallel scalar computer platforms

Methods

Results

Conclusion