Analysis of Flow Characteristics Within USQ's Icing Wind Tunnel

Crosby, James (2021) Analysis of Flow Characteristics Within USQ's Icing Wind Tunnel. [USQ Project]

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CROSBY James dissertation_redacted.pdf

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Ice crystal icing is a relatively new phenomenon which has been brought about by the continual improvement of the aviation industry. At the flight altitudes of modern-day aircraft, the residence of tropical thunderstorms results in dense clouds of ice particles. These particles are unable to be detected by current aircraft equipped radar systems. They pose no threat to the external surfaces of the aircraft, however begin accreting within the turbofan engines. This is a result of the higher temperatures which partially melt the particles allowing them to adhere to the inner surfaces. Accretion continues until large masses of ice are ingested deeper into the engine (Mason et al. 2011). This has resulted in both engine failures and significant degradation. Two of the most pronounced failures were Colgan Air Flight 3407 where 50 lives were lost, and Air France Flight AF447 recording a total of 228 fatalities (Appiah-Kubi et al. 2013, Oliver et al. 2017). Due to the high risk surrounding practical data collection, wind tunnel simulations become the most reliable source of expanding current knowledge.

In 2013 the University of Southern Queensland initially commissioned their icing wind tunnel facility within the P3 building of the Toowoomba campus (Saleh 2013). Further advancements were then made by Saeed (2019) mainly through the introduction of a new drive fan and down stream sections. The facility utilises liquid nitrogen to cool a stream of air in which water droplets are injected. As the droplets are injected, they instantaneously freeze creating ice particles. These particles are then drawn through a conical diffuser where they are mixed with ambient air supplied by a secondary drive fan. The main fan draws this fluid into a nozzle contraction with an exit diameter of 170 mm, that acts to increase the flows velocity. Leaving the nozzle, the flow enters a test section of size 302.5×302.5×610 mm. Initial characterisation demonstrated the facilities potential, however, this highlighted the vast improvements that still remained (Saeed et al. 2019).

These improvements included six main points: – Humidity Control – Melting Ratio Control – Temperature Control – Improved Instrumentation – Measurement of Particle Size Distribution – CFD Simulations.

Working under an overarching technical paper, the identified aims were to provide a computational model of the facility which successfully matched the characterisation results achieved through improved instrumentation. This would further allow for measurements surrounding particle distributions to be made. Hence, the aim of the dissertation was to characterise the flow within the wind tunnels test section based upon the recent modifications. Thus, extending the work of both Saleh (2013) and Saeed (2019) respectively.

To achieve this, experimental data was initially recorded and supplied as part of the overarching paper (Saleh et al. 2021). This allowed for the development of a clean flow computational model through ANSYS Academic R1 2021. The key parameters from the simulation were the use of a K-Epsilon Realizable viscous model coupled with specified mass flow rates and a representative inlet vent. The mass flow rates were adjusted to represent increasing and decreasing the secondary fan power across intervals of 10 %. These results were verified against experimental profiles where the total observed error was below 1 %. An injection of particles was then simulated through DPM, where the diameter was varied between 10 and 60 µm and the LWC between 3 and 10 g/m3 . Comparisons were made across a range of models and the results recorded.

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Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering (1 Jul 2013 - 31 Dec 2021)
Supervisors: Saleh, Khalid
Qualification: Bachelor of Engineering (Mechanical)
Date Deposited: 03 Jan 2023 01:05
Last Modified: 26 Jun 2023 01:08
Uncontrolled Keywords: ice tunnel, ice, flight, aviation, accretion, wind tunnel, computational model, viscous model, mass flow rate

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