Pusat Pengajian Kejuruteraan Aeroangkasa - Tesis

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Browsing Pusat Pengajian Kejuruteraan Aeroangkasa - Tesis by Author "Seeni, Aravind Seeni"

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    Effect of grooves on aerodynamic performance of a low reynolds number propeller
    (2020-10-01)
    Seeni, Aravind Seeni
    UAVs in the future will be designed for next-generation applications such as product delivery from source to end-user. These UAVs weigh in the range of 1 to 10 kg and are powered by small-scale propellers that operate in the low Reynolds number (Re) regime (<100,000). The design of low Re propellers has gained particular importance in the research community with the development of UAVs. Small-scale propellers typically have low aerodynamic efficiency. Improvement in aerodynamic performance and efficiency of these propellers will enhance the endurance and operational range of UAVs. The desired requirement is a propeller design that can produce improved thrust and reduced torque. In order to fulfil such an objective, a novel technique known as the grooved design is studied on a small-scale propeller of pre-defined geometry. This grooved design is based on passive flow control, a technique in which the aerodynamic characteristics of a body is enhanced through the modification of surface geometry. A numerical study is performed on a baseline Applied Precision Composites 10x7 Slow Flyer propeller to investigate grooved passive flow control technique on propellers. Computational Fluid Dynamics as a method to solve Reynolds Averaged Navier Stokes equations is used as a tool to analyse this novel design. A steady, incompressible flow around the propeller is assumed. The commercial code ANSYS Fluent is selected as the solver. First, 2D simulations are conducted on NACA 0009 airfoil at very low Re of 20000 to study the flow characteristics of an airfoil at such low Re. The result showed at such low Re, as the α increases, the turbulence wake contours advanced from trailing edge to leading edge. Secondly, the effect of groove geometry variation is analysed. Grooved cross-sections considered in this study are rectangular in geometry with dimensions 0.1×0.1mm, 0.1×0.2mm, 0.1×0.3 mm, 0.2×0.1mm, 0.2×0.2mm and 0.2×0.3mm and placed at 4 specific locations, 0.09c, 0.17c, 0.32c and 0.42c from leading edge. Finally, the effect of positioning multiple grooves is investigated in which grooves of dimensions 0.1×0.2 mm, 0.1×0.3mm, 0.2×0.1mm, 0.2×0.2mm and 0.2×0.3mm are placed interchangeably at 0.09c, 0.17c, 0.32c and 0.42c. 53 different single and multi-grooved designs constitute the study in total. The results of the study showed that for the model with 0.2×0.1mm groove at 0.17c, the efficiency improved marginally over baseline for 11 cases of advance ratios and decreased for 3 cases of advance ratios. For all other models, the efficiency did not improve relative to baseline for most and/or all advance ratios.