Master's Thesis

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Start date: 2019End date: 2019

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    PREDICTION OF ICE ACCRETION AND CFD ANALYSIS OF NACA 2412 AIRFOIL FOR EVALUATION OF AERODYNAMIC PERFORMANCE DEGRADATION
    (DEPARTMENT OF AERONAUTICAL ENGINEERING, 2019-08) FERDOUS, MAHBUBA
    High altitude flights possess significant icing hazard in certain type of atmospheric conditions. This ice accretion on aircraft wing leading edges and engine nacelle pose threat to the flight safety. From early days of beginning of high altitude flights, numerous studies have been undertaken to determine the effects of icing on aircraft performance. Bangladesh is now moving at galloping pace in the aviation industry, and is expected to take leap of high altitude flight designs in near term period. This could be accomplished if several technologies are developed in-house prior to design and development of high altitude flights. One such requirement is the development of code for prediction of ice accretion and subsequently to design the anti-icing system. With this long term goal in mind, the present research focuses on understanding of the analytical approaches to predict ice accretion physics on aircraft wing cross section. Using the existing ice accretion thermodynamic and other conservation laws presented in open literature, a computer code was developed to predict the ice accretion over the airfoil. The code developed was validated against the experimental ice shapes from the open literatures. Using the developed code, the ice accretion prediction is undertaken on a specific airfoil i.e. NACA 2412, a most common airfoil cross section for moderately high altitude flights. The aerodynamic performance of the predicted ice accretion was analyzed using the Computational Fluid Dynamic (CFD) technique. The aerodynamic study was undertaken for three different icing conditions and it suggests that the ice accreted airfoil possesses lower lift than the base airfoil. It is also observed that the increase in the drag for ice accreted airfoil is significant as compared to base airfoil. Results of the study show that, most critical and worst icing occurs in presence of altocumulus clouds forming mixed ice on the airfoil leading edges. Such icing conditions result in reduction in lift coefficient and increase in drag coefficient approximately by 90% and 800% respectively compared to the base airfoil. These observations are in consonance with the published literature available in open domain. The current research is considered as the stepping stone for subsequent development and improvement of icing codes as well as design of anti-icing systems.
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    STUDY OF MULTISPECIES NANO-PARTICLES TO ENHANCE THERMO-HYDRAULIC PERFORMANCE IN MICROCHANNELS
    (DEPARTMENT OF AERONAUTICAL ENGINEERING, 2019-08) RASHID, MOHSINA
    Nanofluid is the colloidal suspension of nano-sized solid particles of metals or metal oxides in base fluids such as water, ethylene glycol etc. When liquid is mixed with nanoparticles, it exhibits substantially higher thermal conductivity than those of the corresponding base fluids. The augmented thermal conductivity of nanofluids over the base fluids is considered one of the driving factors for enhanced heat transfer performance of nano-fluids. The forced convection heat transfer of nanofluid is investigated by numerous researchers over the last few years. Recently, multispecies nanofluids have been defined as a new class of nanofluids with possible applications in almost all fields of heat transfer. The idea of using multispecies nano-fluids is expected to improve the heat transfer characteristics of individual nanofluids and to beneficially combine different properties from metal oxides, metals etc. The present research work is undertaken using the Computational Fluid Dynamics (CFD) to analysis and assess the high performing nanofluid for micro-channel applications. The study considers three metal oxide, two metal nano particles and their combinations in the base fluid i.e. desalinated water. The study is conducted for different Reynolds numbers and heat capacity. The performance of the nano-fluids is assessed based on the convective heat transfer coefficient, Nusselt number and pumping power requirement based on total pressure loss. The extensive numerical analysis suggests that MgO-Water nano-fluid possesses excellent heat transfer performance over other combinations considered. Study also reveals that the metal oxides possess better cooling performance in terms of convective heat transfer coefficient as compared to metal nanofluids. Among multispecies nanofluids of Ag-MgO-Water, Al2O3-Cu-Water and CuO-Cu-Water, the Al2O3-Cu-Water nano fluid performed better providing highest Nusselt number which is approximately 6% over and above that provided by pure water. Utilizing the data generated by parametric study for different nano-fluids, two combinations nanofluids are utilized for design of a compact heat exchanger with three different heat capacities i.e. 1 kW, 50kW and 100 kW. The hydraulic performance of this heat exchanger was compared in terms of pumping power requirements and it revealed that pumping power requirement increases nearly exponentially for higher Reynolds numbers.