A representative interactive linear-eddy-model (RILEM) for simulating spray combustion

Tim Lackmann

A representative interactive linear-eddy-model (RILEM) for simulating spray combustion
Doktorsavhandling, 2017

Engine development aims at reducing pollutant emissions (e.g. NOx , soot, UHC) while maintaining high efficiencies. Detailed experimental results in combination with precise numerical predictions are of great importance in order to develop combustion systems for new clean and efficient inter- nal combustion engines. Computational fluid dynamics (CFD) tools must be able to deal with multi-mode (premixed, partially premixed and non- premixed) and multi-regime (from kinetically controlled to mixing con- trolled) turbulent combustion under various conditions (low temperatures, high pressures, high EGR rates). Work on laboratory flames [1, 2] clearly demonstrates the strong need to account for the impact of unresolved tur- bulent fluctuations of temperature and composition on chemical reaction rates in Reynolds-averaged and large-eddy simulations (LES) of turbulent combustion. Combustion models that neglect this so called turbulence- chemistry interaction (TCI) cannot predict fundamental physical phenom- ena like local or global extinction and re-ignition, possibly leading to in- precise predictions of essential quantities including heat release rates, tem- peratures and emissions. In order to maximize volumetric combustion ef- ficiency and minimize pollutant formation, it is desirable to maximize the rate of combustion subject to the limits of overall flame stability. These limits of flame stability are determined by the rate of local extinction. Es- pecially in new combustion concepts for engines, including stratified charged compression ignition (SCCI), lean stratified premixed combustion, and the use of high levels of exhaust gas recirculation (EGR) the impact of the flow field on the chemistry plays an important role. This thesis is divided into two parts. The first part deals with the intro- duction of a new regime independent combustion model for engine applica- tions, which is able to predict turbulent combustion under the beforemen- tioned challenging conditions, while the second part deals with the extension of existing knowledge about extinction in non-premixed combustion.

engine simulation

turbulent combustion

regime independent

HA3

Opponent: Prof. Dr.-Ing Christian Hasse, Technical University Freiberg, Germany

Författare

Tim Lackmann

Chalmers, Tillämpad mekanik, Förbränning och framdrivningssystem

Forskning Andra publikationer

Lackmann T., Kerstein A.R., Oevermann M., A representative linear eddy model for simulating spray combustion in engines

Lackmann T., Nygren A, Karlsson A., Oevermann M., Investigation of turbulence-chemistry interactions in a heavy-duty diesel engine with a representative interactive linear eddy model

"A representative interactive linear-eddy-model (RILEM) for
simulating spray combustion"

or in other words

"A new approach for analysing combustion processes in engines"

The goal of this thesis is the further improvement of combustion engines in
terms of efficiency and emissions. Especially the reduction of
pollutant formation is of
serious concern to the whole society.
New combustion concepts decrease emissions. These new concepts
require new computational tools,
which are able to predict combustion for those specific conditions.
The first part of the thesis introduces a new model, which is able
to investigate combustion engines operating under
non-standard combustion modes,
while the second part of the thesis deals with the
extension of existing knowledge about extinction in flames.
Both topics contribute to the development of clean and high efficient
combustion engines.

Ämneskategorier

Maskinteknik

Energiteknik

Strömningsmekanik och akustik

ISBN

978-91-7597-611-2

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4292

Utgivare

Chalmers

HA3