Modelling and experimental study of automotive fuel droplets and sprays heating and evaporation

Research questions

1. Is it possible to perform accurate and CPU efficient modelling of realistic automotive fuel droplet heating and evaporation using modified commercial Computational Fluid Dynamics (CFD) codes, for example via the implementation user defined functions (UDF) in ANSYS Fluent?
2. Can the model be generalised for various forms of multi-component fuels and automatically select suitable quasi-components for accurate and efficient analysis?
3. Can we validate the developed models using available experimental data?
4. Do these validated models then enable accurate simulation of heating, evaporation and auto-ignition for realistic engineering applications?

Aims and objectives of the investigation:
To develop a new accurate and CPU efficient model for the analysis of realistic automotive fuel droplet heating and evaporation using the modified commercial Computational Fluid Dynamics (CFD) code ANSYS Fluent and to validate this model using available experimental data.

Objectives:
1- To implement the previously developed Model of Discretised Components and the Multidimensional Quasi-discrete Model into ANSYS Fluent, via the utilisation of User Defined Functions, and comparing the results with those predicted by the previously developed zero-dimensional code and experimental data where appropriate;
2- To perform optimisation analyses for the selection of quasi-components in the Multidimensional Quasi-discrete Model; further development of the model to enable it to select these quasi-components automatically based on pre-determined criteria;
3- To investigate feasibility of generalising the Discrete Component Model and Multidimensional Quasi-discrete Model taking into account non-sphericity of droplets; and applicability for fuel spray modelling.
4- To investigate the feasibility of combining the new model with an auto-ignition model (the auto-ignition process will be approximated using the Shell auto-ignition model);
5- To investigate the robustness of the model using Diesel and gasoline fuel droplets not used in the previous analysis;
6- To validate the predictions of the model using available or in-house experimental data.

The project will focus on the development of a new model of automotive fuel droplet heating and evaporation and validation of this model against available experimental data. The model to be developed will be based on the previous works developed by the lead supervisor in collaboration with Dr Al Qubeissi (Former research student, supported in the form of studentship by the University of Brighton) (Sazhin, 2014; Sazhin et al., 2014a,b; Al Qubeissi et al., 2015a,b; 2017).

These models took into account temperature gradient and species diffusion inside droplets based upon previously developed analytical solutions to the heat transfer and species diffusion equations. The effects of recirculation inside droplets was taken into account based on the Effective Thermal Conductivity and Effective Diffusivity models.
In the case of automotive fuels with relatively small number of components for fuels such as biodiesel the focus was on the diffusion of the individual components in the liquid phase by utilizing the Discrete Component Model (Sazhin et al., 2014a; Al Qubeissi et al., 2015a).

In the case automotive fuels with large number of components like that of Diesel and gasoline fuels, the focus shifted to the diffusion of the quasi-components in the liquid phase as described in the Multidimensional Quasi-discrete Model (Sazhin et al., 2014b; Al Qubeissi et al., 2015b; 2017).
The latter model had allowed a solution to take into account the complexity of Diesel and gasoline fuel composition which includes the presence of up to 98 various components in Diesel fuel.