Investigation of the Semi-Mechanistic Boiling Model for use in Numerical Aeroengine Fire Tests
| dc.contributor.author | Logan, Dylan | |
| dc.contributor.copyright-release | No | |
| dc.contributor.degree | Master of Applied Science | |
| dc.contributor.department | Department of Mechanical Engineering | |
| dc.contributor.ethics-approval | Not Applicable | |
| dc.contributor.external-examiner | Dr. Michael Pegg | |
| dc.contributor.manuscripts | No | |
| dc.contributor.thesis-reader | Dr. Baafour Nyantekyi-Kwakye | |
| dc.contributor.thesis-supervisor | Dr. Dominic Groulx | |
| dc.contributor.thesis-supervisor | Dr. Mohammad Saeedi | |
| dc.date.accessioned | 2025-12-08T15:20:30Z | |
| dc.date.available | 2025-12-08T15:20:30Z | |
| dc.date.defence | 2025-09-29 | |
| dc.date.issued | 2025-12-03 | |
| dc.description | In aeroengine design, mechanical components which contain oil must undergo experimental fire safety validation to ensure they will survive an aeroengine fire incident without leaking oil into the fire. Aeroengines operate in intense thermal conditions where an engine's capability to endure a fire incident may be the determining factor in avoiding failure of the aviation systems. Experimental fire tests are expensive and provide limited data due to the destructive nature of the tests. A numerical simulation model developed alongside experimental results would allow for a repeatable method of determining how engine components respond to fire incidents, lessening reliance on costly fire tests and providing design insight prior to fire safety testing. To accurately predict how solid temperatures change with time during a fire test requires various physical models that capture turbulence, multiphase flow, heat transfer, and vapor generation through boiling. The thesis applies these physical models with an emphasis on incorporating a boiling model. When a fluid boils, more heat to transferred from the wall to the fluid than pure convection due to vapor generation and flow disruption. Alternatively, a catastrophic boiling scenario can occur when too much vapor is generated and the fluid is no longer in contact with the wall. The heat transfer cooling the solid will drop drastically, corresponding to quick rises in solid temperatures, typically above the solid's melting temperature. The semi-mechanistic boiling model, available in the commercial computational fluid dynamic software ANSYS Fluent, is selected as the most applicable boiling model for industry due to its several parameters that can tuned to match experimental results. The selected boiling model and its tunable parameters are investigated by calibrating the model to the results of a publicly available channel cooling test case. In addition to learning the effects of the various tunable parameters, a change in heat flux solution trend is identified as possibly being able to spot conditions for when a catastrophic boiling scenario occurs. The selected boiling model is then applied to a simplified oil tank geometry representative of a complex aeroengine component. The findings demonstrate that the selected model effectively captures boiling-induced cooling and vapor generation effects. However, several limitations were encountered, including uncertainty in the thermophysical properties of oil vapor, difficulties achieving suitable mesh resolution near heated walls due to stability constraints, difficulty incorporating some oil tank boundary conditions, and a lack of a numerical combustion model to accurately represent the high heat fluxes from a fire. This work acted as a proof of concept, determining the future work required. Next steps are to incorporate more complex multiphase boundary conditions and to couple the multiphase-boiling model to a combustion burner model. With accurate boundary conditions for a test specimen, the boiling model can be tuned to experimental results. | |
| dc.description.abstract | This thesis investigates the application of the semi-mechanistic boiling model within the mixture multiphase framework in ANSYS Fluent to improve the accuracy of numerical simulations of aeroengine fire tests. Developed in collaboration with Pratt & Whitney Canada (PWC), this work addresses critical limitations in existing computational methods which fail to capture the complex multiphase heat transfer processes, particularly those involving the boiling of lubricating oils under fire conditions. The research includes an investigation of the boiling model and its tunable parameters through calibration against experimental data of a publicly available channel cooling test case, and an application to a simplified oil tank geometry representative of a complex aeroengine component. The findings demonstrate that the selected model effectively captures boiling-induced cooling and vapor generation effects, leading to more accurate temperature predictions and improved simulation reliability. | |
| dc.identifier.uri | https://hdl.handle.net/10222/85542 | |
| dc.language.iso | en | |
| dc.subject | Computational Fluid Dynamics | |
| dc.subject | Mechanical Engineering | |
| dc.subject | Multiphase | |
| dc.subject | Heat Transfer | |
| dc.subject | Boiling | |
| dc.subject | Mass Transfer | |
| dc.subject | Aerospace | |
| dc.subject | Aeroengine | |
| dc.subject | Fire Safety | |
| dc.title | Investigation of the Semi-Mechanistic Boiling Model for use in Numerical Aeroengine Fire Tests |