Krishnil R. Ram

Low Reynolds number airfoil optimization for wind turbine applications using genetic algorithm

Optimization of a low Reynolds number airfoil for use in small wind turbines is carried out using a Genetic Algorithm (GA) optimization technique. With the aim of creating a roughness insensitive airfoil for the tip region of turbine blades, a multi-objective genetic algorithm code is developed. A review of existing parameterization and optimization methods is presented along with the strategies applied to optimize the airfoil in this study. A composite Bezier curve is used to parameterize the airfoil. The resulting airfoil, the USPT2 has a maximum thickness of 10% and shows insensitivity to roughness at the optimized angles and at other angles of attack as well. The characteristics of USPT2 are studies by comparing it against the popular SG6043 airfoil. While a slight loss in lift is noticed for both airfoils, the drag increments due to early transition are noticeable as well. The airfoil is also studied using computational fluid dynamics (CFD) and wind tunnel experiments during free and forced transitio...

A Regional University Perspective on Engineering Education of Multi-Cultural Freshman Students From South Pacific Countries

Of late, there is a growing need for quality engineers who have the ability to solve complex engineering problems with reasonable knowledge of ethics and economics. This has led many universities to pursue accreditation by professional engineering bodies. While the accreditation process installs a standardized system of quality teaching, it is important that the engineering entrants have a degree of understanding that allows implementation of quality teaching methods. This study looks at the performance of first year engineering students in a bid to identify major issues that students face in a Bachelor of Engineering program. The learning of students in the School of Engineering and Physics at the University of the South Pacific is influenced by interactions of at least 12 different cultures from the 12 member countries of the university. The study looks at how students perform across cultures in the first year mechanical engineering courses, mainly engineering mechanics and engineering graphics & design. The general trend over the last five years shows that while the student numbers in the program have been increasing, student performance in one course seems to be improving but declining in the other; the two courses differ considerable in contents, required skill sets, and assessment methodologies. The study also presents possible reasons for the varied performance by considering issues such as cultural and academic backgrounds, use of teaching tools and resources, and revisions to the course and program and looks at how multi-cultural engineering education can be improved. The number of female students taking up engineering as their major is also looked at and positive trends are seen with female participation increasing from 7.6% in 2008 to 13.9% in 2013.Copyright

Optimization of Hydrofoils for Horizontal Axis Marine Current Turbines Using Genetic Algorithm

As fossil fuels near depletion and their detrimental side effects become prominent on ecosystems, the world is searching for renewable sources of energy. Tidal energy is an emerging and promising renewable energy resource. Tidal turbines can extract energy from the flowing water in a similar way as wind turbines extract energy from the wind. The upside with tidal turbines is that the density of water is approximately 800 times greater than that of air and a tidal turbine harnessing the same amount of power as a wind turbine can be considerably smaller in size. At the heart of the horizontal axis marine current turbines are carefully designed hydrofoil sections. While there is a growing need to have hydrofoils that provide good hydrodynamic and structural performances, the hydrofoils also have to avoid cavitation for safe operation. This study uses a genetic algorithm optimization code to develop hydrofoils which have the desired qualities mentioned above. The hydrofoil problem is parameterized using a composite Bezier curve with two Bezier segments and 11 control points. Appropriate curvature conditions are implemented and geometric constraints are enforced to maintain the hydrofoil thickness between 16 to 18%. XFOIL is used as the flow solver in this study. The hydrofoils are optimized at Reynolds number of 2 million and for angles between 4 to 10 degrees. The best foil from the results, named USPT4 is tested for performance with the CFD code ANSYS CFX. The CFX results are validated with experimental results in a wind tunnel at the same Reynolds number. The hydrofoil’s performance is also compared with a commonly used NACA foil.Copyright

Airfoil Optimization for Small Wind Turbines Using Multi Objective Genetic Algorithm

Small wind turbines are gaining popularity due to their ability to meet community or domestic needs in isolated areas with relatively easier installation and lower cost than large wind turbines. This study looks at optimizing airfoils for use in small horizontal axis wind turbines. The optimization looks to maximize the lift coefficient (Cl) while minimizing or fixing the drag coefficient (Cd). To satisfy these two objectives a multi–objective genetic algorithm is used. The airfoil is parameterized using a composite Bezier curve with two Bezier segments and 11 control points. Appropriate curvature conditions are implemented at the leading and trailing edge of the airfoil and geometric constraints are applied to maintain the maximum thickness between 8% to 14% of the chord for structural reasons. An existing genetic algorithm (GA) code is modified in C++ to generate suitable airfoils using the 13 control points and pass the coordinates to a solver for analysis. As a result four new airfoils are generated for application in low Reynolds number (Re) flow. The characteristics and suitability of the four airfoils are discussed while comparing them to the popular SG6043 airfoil.Copyright