Turbofan Engine Crystal Icing: Computational Fluid Dynamics Study

Sims, Daniel (2021) Turbofan Engine Crystal Icing: Computational Fluid Dynamics Study. [USQ Project]

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SIMS Daniel dissertation_redacted.pdf

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Turbofan engine icing takes the form of crystal icing. This phenomenon is relatively new and is not fully understood yet. The icing occurs due to the ingestion of crystal ice particles into the aircraft’s turbofan engine. The ice particles melt into a mixed phase of ice and supercooled liquid. The liquid increases the potential for adhesion of the particles to the surfaces which they contact due to reducing impulse. The particles can then cool the temperature of surfaces within the engine; including the stators of the low pressure compressor. This allows for particles to refreeze on these surfaces. This occurs when aircraft fly in conditions of increased moister that has fully solidified; such as at high altitudes and in convection zones. The issue of engine icing usually occurs at conditions of −40 ◦C and altitudes of 10 km.

Many institutions have begun to research this topic within the last decade. This usually occurs in facilities known as icing wind tunnels. The University of Southern Queensland has even developed an icing wind tunnel facility to conduct research for both themself and for external institutions to utilise. Icing wind tunnels have test condition limitations as they are a physical facility. Altering the conditions of an icing wind tunnel requires much more work than altering conditions in a simulation. Computational fluid dynamic models present the ability to simulate the functions of an icing wind tunnel and have been utilised in multiple studies thus far.

This dissertation aimed to investigate turbofan engine icing through the use of a Computational Fluid Dynamic model built in ANSYS Fluent utilising a Workbench. This study aimed at using the new stand alone Fluent Icing software, however, issues with the software resulted in a discrete phase model (DPM) being implemented in the regular Fluent. The DPM was used to inject particles at different sizes, densities and temperatures. As a result of changing the approach to the use of the DPM late in the study, the model had multiple limitations. This included not having the required heat transfer equations being utilised in the models calculations. This resulted in the model not being capable of producing actual ice accretion profiles. Another limiting factor was that a steady state model was created opposed to a transient. This prevented growth rates from being calculated.

Two airfoils were tested in the model. A NACA0012 airfoil was tested which allowed for the simulations turbulence model settings to be verified as there was plenty of data on the airfoil. An airfoil’s profile was sourced that were repetitiveness of a generalised stator from a turbofan engine compressor. This allowed the study to be relative to the issue at hand.

The computational model was capable of calculating results in the form of particles trapped and accretion rates. Multiple parameters affects on the results were tested over 112 tests. The parameters of particle diameter, density and temperature were tested. The affects of the airfoil’s angle of attack and type was also tested. The results allowed for multiple insights to be concluded. The findings were not abstract to those previously determined in other studies. However, the results are useful as many studies results are required to confidently confirm a parameters affect on the icing. It was generally observed that increased magnitude of angle of attack increases the icing rates. For the stator airfoil tested, the negative angles of attack resulted in smaller accretion rates than for the positive angles. This was due to the profiles curvatures.

This study’s main service was proving the foundations for a turbofan engine icing CFD model that can be expanded in further studies. Many issues were accounted when preparing the computational model. This study has outlined how to overcome these issues. Future studies can therefore bypass these issues and spend their time creating models with higher capabilities than this study’s.

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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 04:31
Last Modified: 26 Jun 2023 02:04
Uncontrolled Keywords: ice, icing, turbofan engine, aircraft, liquid, fluid dynamics, airfoil, heat transfer, ANSYS
URI: https://sear.unisq.edu.au/id/eprint/51838

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