Turbulence-Chemistry-Interaction Modelling in 3D-CFD for Study of Auto Ignition Phenomena University of Rostock

Format:

Conference/Event

Author/Creator:

Benz, Benz, author.

Contributor:

Hassel, Egon

Hoffmeyer, Henrik

Michels, Karsten

Nocke, Jürgen

Conference Name:

SAE 2012 World Congress & Exhibition (2012-04-24 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2012

Summary:

From the point of view of the customer purchasing a car theecological as well as the price aspect is in the main focus todayand in the years that come. This will increase due to globalwarming, the accelerated depletion of raw materials and significantprice increases. Downsizing of spark ignition engines is anopportunity to lessen these shortcomings by decreasing thedisplacement volume of the engine and for a constant powerincreasing the load. In the case of extreme downsizing, especiallyin the case of low engine speed, auto ignition occurs in theair/fuel mixture. As a consequence cylinder pressure tends toexhibit high amplitudes and frequencies, which can lead to enginedamage.This paper presents a model which allows linking 3D-CFD with adetailed chemical reaction system. Therefore a three-dimensionalnumerical model in OpenFOAM is formulated that includes allphysical characteristics of a direct-injected, highly charged sparkignition engine. The conservation equation for mass, momentum andenergy form the mathematical basis for the modeling approach.Additional equations for spray modeling and forturbulence-chemistry interaction are required whereat the latterbases on a partially stirred-reactor approach. This model wasdeveloped and implemented in OpenFOAM at the Chalmers University ofTechnology in Göteborg, Sweden.A detailed chemical reaction system that describes thecombustion of iso-octane/n-heptane and air is used. This mechanismcould be reduced by means of sensitivity and 0D-reactor studies.Thus it is adopted to the cold-flame range at which auto ignitionoccurs. The reduction of the chemical mechanism has greatimportance especially for the coupling with the CFD-code.Several hypotheses for causes of autoignition already exist. Theaim of this paper is to verify such causes with CFD methods,particular the sensitivity with respect to engine parameters. Anoperating state at low engine speed and high load is chosen as areference point. Measured pressure history can be applied tovalidate the complete numerical model. Finally it is used for asystematic parameter study to gain insight into the character ofautoignitions

Notes:

Vendor supplied data

Publisher Number:

2012-01-0158

Access Restriction:

Restricted for use by site license