The foundation of graduate training at UTIAS is high-quality research on technically challenging projects. The following is an exemplary selection of projects to be pursued under the theme of Sustainable Aviation, divided into four research themes.
I Aerodynamics and Aeroacoustics
II Lightweight Structures
III Biofuels, Combustion and Atmospheric Impacts
IV Life Cycle Assessment and Multidisciplinary Optimisation
I Aerodynamics and Aeroacoustics
Improved aerodynamics through drag reduction is one important means of reducing aircraft fuel consumption and emissions. Large reductions in drag can be achieved through unconventional aircraft configurations, such as the blended wing body, and control of separated and attached shear layers. Investigating unconventional design and the impact of flow control requires radically new analytical tools.
Algorithms for Aerostructural Optimisation (Zingg): This project involves the development of novel algorithms for aerostructural optimisation based on the Reynolds-averaged Navier-Stokes equations, including the capability to predict the location of transition from laminar to turbulent flow. When such algorithms are applied to drag minimisation of unconventional aircraft configurations, the optimiser can move the transition point aft to produce robust aircraft designs with minimum drag. The impact of speed on efficiency will be investigated for aircraft of various sizes. The new algorithms will be based heavily on algorithms recently developed at UTIAS for aerodynamic shape optimisation, which do an excellent job of minimising wave and induced drag and provide a solid foundation for the proposed project.
Aeroacoustic Optimization (Moreau, Zingg): This co-supervised project involves aeroacoustic optimization using analytical noise models based on RANS solutions. The latter have been recently developed at the Université de Sherbrooke for the prediction of airfoil noise. Noise pollution, particularly in the proximity of airports, is of great concern to modern aircraft and engine manufacturers. The multiple blunt struts and cavities in a landing gear system both contribute to drag increase and noise generation.
Aeroacoustic Optimization of Fairings: Another co-supervised project (Zingg, Moreau, Lavoie) will therefore involve the aeroacoustic optimization of fairings that could simultaneously reduce both noise and drag.
Smart Control System Development to Delay Boundary Layer Transition (Lavoie): One specific project will be to develop a smart control system to delay boundary layer transition using sensors and actuators located at the aircraft surface. Since active laminar flow control is an important technology for reducing drag in the future, it is important to investigate the potential of laminar flow for unconventional configurations.
Passive Flow Control Methods (Ekmekci): Passive flow control methods can also be highly beneficial. This project will investigate wing-body junctions, which contribute up to 10% in drag on current aircraft, and consider passive means of mitigating their contribution to the overall drag.
II Lightweight Structures
The two primary means of reducing aircraft weight are the replacement of metallic parts with composite parts, and the improvement of composite design techniques so that composite parts can be made lighter. New types of composite sandwich panels with truss-like cores promise to replace metallic panels. Moreover, it is possible to choose an advantageous geometry so that the truss possesses additional functional properties, such as vibration resistance or low thermal expansion. To integrate truss-core panels into aircraft requires better understanding of how they behave in use under mechanical and environmental loading.
Models of Truss-core Composite (Steeves): This project will use analytical modeling, finite element simulations and experimentation to develop models of truss-core composite sandwich panel behaviour, failure mechanisms and post-damage residual properties.
Optimization of Composite Fibre Layouts in Three-Dimensional Structures (Steeves): Another project will use topology optimisation and surrogate modeling to optimise the layout of composite fibres in three-dimensional structures that can be manufactured using existing textile fabrication techniques. Structural and materials research also provides inputs into aerostructural optimisation and life cycle assessment, enabling co-supervised projects.
III Biofuels, Combustion and Atmospheric Impacts:
The combustion of biofuels remains problematic because significant changes in performance and emissions are expected when biofuels are used at the high pressures associated with existing aircraft engines. Future high-efficiency engines using biofuels will operate at still higher pressures and fuel-to-air ratios. Furthermore, jet fuel is generally used as a heat sink to remove waste heat in aviation engines, on top of its primary role as an energy source. Heating fuel results in several liquid-phase chemical reactions involving hydrocarbon molecules, dissolved oxygen and impurities, leading to the build up of carbon deposits within the fuel system that can constrict fuel flow, decrease the effectiveness of surfaces acting as heat exchangers and potentially cause engine shutdown.
The International Civil Aviation Organization (ICAO) states in its Environmental Report 2010 that the “gain in efficiency from technological and operational measures does not offset the overall emissions that are forecast to be generated” and that, consequently, biofuels are likely to form a major part of overall emissions reduction in aviation. The global market for biofuels in 2015 is expected to exceed $50 billion. Canada is home to Biox, Dupont, Iogen, Mascoma Canada and Greenfield Ethanol, significant producers of liquid biofuels as well as several engineering consulting agencies specializing in renewable energy and environmental assessment (e.g. Hatch, GeoSyntec). Increasing awareness of environmental issues in aviation significantly increases the importance of life cycle assessment; companies such as Quantis Canada are specialists in life cycle assessment. In the short to medium term there will be increasing demand for people trained in these strategic areas, and even higher demand in the long term.
Biofuel Synthesis Project (Master): uses acyl transferase (MsAcT) from Mycobacterium smegmatis to catalyse transesterification of long-chain fatty acids with methanol or ethanol in aqueous conditions. The aim of the project will be to mine publicly available genome sequences for proteins that are homologous to Ms-AcT, and to screen recombinantly expressed proteins for transesterification activity in aqueous conditions. Long-chain alcohols and fatty acids will be included in the enzyme screens, and thin layer chromatography will initially be used to rapidly identify active protein targets.
Combustion Characteristics of Gaseous and Liquid Biofuels (Gülder, Groth): A co-supervised project will be to conduct a coherent, systematic, combined experimental and numerical study focusing on the high-pressure combustion characteristics of a wide range of gaseous and liquid biofuels, and to assess the thermal oxidative stability of various liquid aviation biofuels. The experimental program will examine the ignition and extinction properties of biofuels at elevated pressures, the sooting tendencies of biofuels at elevated pressures, and the influence of thermal stressing of biofuels on ignition and soot formation.
Accelerating Design Optimization (Nair): Finally, the impact on the atmosphere of emissions from biofuel-powered aircraft engines will be studied. One project in atmospheric physics will consider the implications of the mix of combustion products from biofuels on the atmosphere at various possible flight altitudes, looking to minimise the overall impact of these products.
IV Life Cycle Assessment and Multidisciplinary Optimisation
Understanding the impact of aviation on the environment requires studying all the energy and resource needs and their associated emissions, from the fabrication of an aircraft, through its operation, and finally to its disposal, a novel topic of critical importance to Canadian aerospace companies.
Technoeconomic and Environmental Perspectives (MacLean): This project investigates, from technoeconomic and environmental perspectives, the potential for the aviation industry to move to lower carbon aviation fuels. There is significant motivation and emerging regulations calling for reductions in greenhouse gas emissions generated by the aviation sector. The vast majority of these emissions result from the combustion of the current petroleum-based aviation fuels during aircraft operation. The project will develop a life cycle-based framework for examining the environmental and economic aspects associated with aviation fuels, apply the framework to examine the life cycle environmental and economic performance of current (reference) fuels as well as alternative fuels in use or being proposed, and determine the conditions required for low carbon fuels to enter the market successfully.
Accelerating Design Optimization (Nair): Applying the results of life cycle assessment to mitigate the impacts of aircraft necessitates optimal design in very complex design spaces. Research work on this topic will focus on the development of surrogate models or emulators for high-dimensional design spaces. This work is driven by the need to develop strategies for accelerating design optimization problems where high-fidelity computational models are used to predict the performance of candidate designs. The research will focus on the construction of real-time emulators for approximating the aerodynamic and structural response as a function of the design variables. This development will allow designers to rapidly explore a wide range of design alternatives in an immersive visualization environment and also enable the acceleration of automated design space search procedures. The goal is to develop optimisation schemes by which aircraft designs with minimum total environmental impact can be selected.