A Physical 0D Combustion Model Using Tabulated Chemistry with Presumed Probability Density Function Approach for Multi-Injection Diesel Engines Institut PRISME - Univ. of Orleans

Format:

Conference/Event

Author/Creator:

Bordet, Bordet, author.

Contributor:

Caillol, Christian

Higelin, Pascal

Talon, Vincent

Conference Name:

International Powertrains, Fuels & Lubricants Meeting (2010-05-05 : Rio De Janeiro, Brazil)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2010

Summary:

This paper presents a new 0D phenomenological approach topredict the combustion process in diesel engines operated undervarious running conditions. The aim of this work is to develop aphysical approach in order to improve the prediction of in-cylinderpressure and heat release. The main contribution of this study isthe modeling of the premixed part of the diesel combustion with afurther extension of the model for multi-injection strategies.In phenomenological diesel combustion models, the premixedcombustion phase is usually modeled by the propagation of aturbulent flame front. However, experimental studies have shownthat this phase of diesel combustion is actually a rapid combustionof part of the fuel injected and mixed with the surrounding gas.This mixture burns quasi instantaneously when favorablethermodynamic conditions are locally reached. A chemical processthen controls this combustion.In the present model, the rate of heat release by combustion forthe premixed phase is related to the mean reaction rate of fuelwhich is evaluated by an approach based on tabulated local reactionrate of fuel and on the determination of the Probability DensityFunction (PDF) of the mixture fraction (Z), in order to take intoconsideration the local variations of the fuel-air ratio. The shapeof the PDF is presumed with a standardized β-function. Mixturefraction fluctuations are described by using a transport equationfor the variance of Z. The standard mixture fraction conceptestablished in the case of diffusion flames is here adapted topremixed combustion to describe the inhomogeneity of the fuel-airratio in the control volume. The detailed chemistry is describedusing a tabulated database for reaction rates and cool flameignition delay as a function of the progress variable c.Premixed zone volume and total entrained ambient gas mass flowrate are calculated using a detailed spray model. Themixing-controlled combustion model is based on the calculation of acharacteristic mixing frequency which is a function of theturbulence density, and on the evolution of the available fuelvapor mass in the control volume.The developed combustion model is one sub-model of athermodynamic model based on the mathematical formulation of theconventional two-zone approach. This zero-dimensional modelincorporates several sub-models describing turbulence,vaporization, and fuel introduction rate. The purpose of thisapproach is to directly relate physical model parameters tooperating conditions and engine parameters.Numerical results from simulations are compared withexperimental measurements carried out on a 2-liter Renault dieselengine. For all investigated operating conditions, simulatedcylinder pressure and heat release rate traces show a goodagreement with experimental measurements

Notes:

Vendor supplied data

Publisher Number:

2010-01-1493

Access Restriction:

Restricted for use by site license