Modeling igniting high-pressure sprays in combustion engines

March 22, 2023

Hesheng Bao defended his PhD thesis at the department of Mechanical Engineering on March 14th.

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Innovations in internal combustion engines relay on detailed understanding of in-cylinder processes such as spray combustion. For his PhD research, Hesheng Bao explored an efficient and predictive spray ignition modeling approach to describe the spray-relevant processes in the cylinders of internal combustion engines.

The dominant power source in our transportation industry is the internal combustion engine (ICE). While there are efforts to replace ICEs with electrical or hydrogen-based options, it’s likely that ICEs will still play a key role over the coming years, particularly when it comes to heavy-duty applications such as in trucks or construction vehicles.

With this being the case, it is imperative that the processes underlying ICEs are optimized so that future engines are both clean and sustainable in terms of their use of fuel. For instance, in heavy duty applications,  direct injection compression ignition is dominant is the dominant approach. Therefore, detailed information regarding underlying spray combustion would be beneficial for the sustainability of ICEs.

Spray ignition modeling

In his PhD thesis, Hesheng Bao explored an efficient and predictive spray ignition modeling approach that captures well the spray-relevant processes for an ICE. For this purpose, several well-characterized igniting sprays in constant-volume combustion chambers at representative conditions corresponding to engines were studied for model validation.

To preserve the fidelity with affordable computational cost, large-eddy simulation (LES) and Flamelet Generated Manifold (FGM) models were adopted for turbulence and combustion modeling, respectively.

Bao created the computational model in the open-source Computational Fluid Dynamics (CFD) software OpenFOAM. His research has resulted in a reliable and affordable computational tool that has been validated in various spray configurations.

Affordable computational tool

Bao’s research has resulted in a reliable and affordable computational tool that has been validated in various spray configurations.

The analysis methods developed by Bao provide a detailed understanding of igniting spray evolution. The performance of the modeling approach also gives great confidence that it can be readily applied to evaluate the performance of advanced combustion concepts.

Furthermore, its inherent sensitivity to detailed chemistry allows the approach to be applied to the emerging variety of low-carbon "new fuels". Hence, Bao has developed an excellent tool to investigate the future of zero-impact internal combustion engines.

Title of PhD thesis: Detailed description of igniting high-pressure sprays using efficient models. Supervisors: Bart Somers and Dirk Roerkaerts.

Media contact

Barry Fitzgerald
(Science Information Officer)

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