Wang, Heyu;
(2024)
Numerical Modelling of Aerothermodynamics in Micro-Gas Turbines with Realistic Geometries.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The heavy use of fossil fuels, being major sources of carbon emissions, has intensified the global warming issue. Consequently, governments and organizations around the world have set a target to reach net zero emissions by 2050. Yet, with the rising needs for energy and transportation, electric engine technologies are not being leveraged to their full potential for various reasons. As a result, combustion gas turbines are expected to remain essential in the foreseeable future. This thesis investigates the aerodynamics, aerothermal performance, and emission characteristics of various components in gas turbine systems. Initial studies focused on the dump diffuser combustor, a simplified representation of a gas turbine combustion chamber, analyzing the aerodynamic effects of geometric parameters such as the pre-diffuser divergence angle and dump gap ratio. The research revealed the potential for optimizing weight, length, and aerodynamic efficiency through design adjustments. In subsequent sections, the aerothermal performance and emissions of a realistic micro-gas turbine geometry were investigated, employing a publicly available model for validation. Key parameters such as non-uniform outlet pressure, fuel-to-air ratio, and fuel injection velocity were identified as pivotal factors influencing the combustor's performance and emission characteristics. Through a thorough analysis of the combustor-turbine interaction, with a focus on clocking effects, the intricate balance and ramifications of various modelling approaches on aerothermal dynamics and soot emissions were elucidated. These findings underscored the significant impact of combustion modelling on predicting the aerodynamic performance of the turbine stage. Notably, unburned fuel migrating downstream the turbine vane was observed to create elevated temperature fields, affecting heat transfer performance. Leveraging clocking effects holds promise for enhancing aerothermodynamic performance and reducing soot emissions. Leading-edge hot-streak impingement clocking was found to enhance aerodynamic efficiency, while mid-passage clocking mitigated turbine vanes' heat load and reduced soot emissions, presenting avenues for optimization. Lastly, recommendations for future research, guided by the insights from the conducted studies, span the domains of compressor-combustor interaction, high-fidelity turbulence resolution, unsteady bladerow simulations, fuel type effects, and diverse operating points, providing a roadmap for further advancements in the field.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Numerical Modelling of Aerothermodynamics in Micro-Gas Turbines with Realistic Geometries |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10192901 |
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