Modelling of Multicomponent Fuel Sprays
Doctoral thesis, 2021

The use of fuel blends (conventional fuels blended with renewable ones) has gained importance in the automotive industry as an option to reduce emissions and dependence on fossil fuels. In order to make the fuel blends commercially viable, computational fluid dynamics (CFD) is used to complement the experiments (done on engines or spray chambers) by providing fundamental insight into spray formation. The work presented in this thesis is focused on modelling and CFD simulation of multicomponent fuel sprays.

The spray model used in this work is the stochastic blob and bubble model (VSB2) which is a discrete multicomponent fuel spray model. One of the strengths of the model is that it uses thermodynamic equilibrium to calculate heat and mass transfer to ensure that there is no over- or under-estimation of the temperature or evaporated mass. The VSB2 also uses minimal tuning parameters for modelling. The present work extended the spray model to handle multicomponent fuels. One of the main challenges in modelling multicomponent fuels is to handle differential evaporation correctly. To address this, a non-linear equation solver was implemented . The solver interfaces with the OpenFOAM code containing the spray model. One of the main benefits of the newly implemented solver is that it can be scaled to handle a large number of fuel components with minimal effort. The multicomponent fuel spray model was validated with experimental data for one, two and three fuel components respectively in three separate cases and showedreasonably good agreement. Apart from this, the model was used to study the influence of non-ideal vapor liquid equilibrium (VLE) and showed that it is important to consider non-ideal VLE for fuels with polar molecules. The model was also used to study the influence of resolving the injector orifice and the counterbore of a gasoline direct engine (GDI) injector in two separate studies. The results of all the studies can be found in the appended manuscripts.

Having thus established the multicomponent fuel spray model in through this work, in future, it can be combined with detailed chemical mechanisms and combustion models to extend the studies to investigate combustion of multicomponent fuels.

diesel and gasoline engine conditions

GDI injector

multicomponent fuel sprays

differential evaporation

resolving counterbore

secondary breakup

stochastic blob and bubble model

resolving injector orifice

CFD

Tryckpressen, SB3, Sven Hultins Gata 8, Göteborg
Opponent: Associate Prof. Bart Somers, Eindhoven University of Technology, the Netherlands

Author

Vignesh Pandian Muthuramalingam

Chalmers, Mechanics and Maritime Sciences, Combustion and Propulsion Systems, Combustions and Sprays

Pandian Muthuramalingam, V., Karlsson, A., Validation of a multicomponent fuel spray model for gasoline direct engine conditions (Engine Combustion Network, Spray G) and influence of resolving the counterbore injector

Transportation is fundamental part of a growing global economy. The by-products produced from the energy conversion processes used to propel vehicles are harmful. For instance, CO2 produced from transportation causes global warming and the raise of average global temperature. Transportation
sector is currently responsible for 24 % of all CO2 emissions. Apart from this the fossil fuels, on which transportation mainly relies is depleting. The sustainable development scenario (SDS) based on the Paris climate agreement aims to prevent global temperatures from raising by more than 2 o C until the end of he century. One of the solutions to solve this problem for the transportation industry in general and the automotive industry in specific is to use fuel blends. Fuel blends consist of conventional fuels blended with renewable ones. In order to make the fuel blends commercially viable, they are tested in laboratory conditions on engines (or simplified set-ups representing engine conditions). To complement the experiments, computational fluid dynamics (CFD) is used to provide deeper insight into the different processes involved in formation and combustion of fuel sprays. The research work presented in this dissertation is focused on modelling and CFD simulation of multicomponent fuel sprays.

The present work extended the existing fuel spray model to handle multicomponent fuels. The main challenge in modelling multicomponent fuels is that each fuel component evaporates at its own rate and in turn influences the evaporation of the other components. This challenge is addressed through the implementation of numerical solver that can be easily scaled to handle a large number of fuel components.

The multicomponent fuel spray model has been validated for one, two and three fuel components respectively in three separate cases and showed reasonably good agreement with experimental data. Once the model was developed, it was applied to study the influence of considering non-ideal thermodynamics to accurately predict multicomponent fuel sprays. In two other studies, the model was used to investigated fuel sprays under gasoline and diesel conditions respectively and provided valuable insights into the fuel spray formation. These insights can be used to optimize combustion systems in vehicles to enable developing viable commercial solutions to reduce the emissions from vehicles and also the dependence on fossil fuels.

Subject Categories

Mechanical Engineering

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

ISBN

978-91-7905-431-1

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4898

Publisher

Chalmers University of Technology

Tryckpressen, SB3, Sven Hultins Gata 8, Göteborg

Opponent: Associate Prof. Bart Somers, Eindhoven University of Technology, the Netherlands

More information

Latest update

1/18/2021