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Fluidic oscillators are used to overcome fluid flow separation on the upper side of the airfoil. The AoA chosen is for stall conditions, namely 16°, 18° and 20°. The type of fluidic oscillator used is a two-feedback channel fluidic oscillator. The chosen element is a triangle because it is easy to implement in complex geometries such as fluidic oscillators. The algorithm used is PISO. The governing equation for solving problems is URANS. URANS is then combined with the k-omega SST turbulence model. A low Reynolds number of 48000 was chosen to simulate the NACA 0015 airfoil. This Reynolds number is calculated based on the chord length of the airfoil. Variations were also made to the fluidic oscillator velocity-inlet value. The velocity-inlet variations given are 25 m/s, 35 m/s, and 45 m/s. The increase in Cl will be more significant if the selected inlet velocity is higher. At an inlet velocity of 45 m/s, the average increase produced was 38.53%. Double FO experienced an increase of 21.99%. Drag reduction is another parameter used to assess the aerodynamic performance of an airfoil. The average drag reduction for a velocity-inlet of 45 m/s is 12.54%. Double FO produces an average drag reduction of 6.80%.

The increase in FO frequency due to the use of BFS is accompanied by an increase in pressure losses. The study was conducted using the URANS governing equation and the SST k-ω turbulence model. Double BFS exhibited the highest frequency, with an average increase of 25.78% over the prototype. In contrast, the average frequency increases of single and triple BFS were 20.29% and 19.6%, respectively. The frequency increase is influenced by the momentum of the backflow in the feedback channel. Double BFS had a lower pressure loss than the prototype model, with 4.54% reduction. The average pressure loss of the single BFS model was 24.9% higher than that of the prototype model, whereas the triple BFS model showed a 0.039% increase. The pressure loss is influenced by the recirculation bubble in the FO chamber. Nondimensional analysis using Strouhal and Euler numbers also showed that double BFS exhibited the best performance. The prototype model and single BFS had a velocity profile shape that is closer to a homogeneous shape. The double and triple BFS exhibited a velocity profile shape that is closer to the bifurcated jet shape. Bifurcated jets, which exhibit a wider spread, are characteristic of oscillatory flows. Thus, it can be concluded that the double BFS FO is more recommended.

An assessment of the longitudinal motion of a hybrid configuration called the aerodynamically alleviated marine vehicle (AAMV) with the presence of waves, is demonstrated in the thesis. The development of this type of vehicle requires a mathematical framework to characterise its dynamics with the influence of external forces due to the waves’ motion. An overview of the effect of waves towards the models of dynamics developed for wing in ground effect (WIGE) craft and high-speed marine vehicles (planing craft) is carried out. However, the overview only leads to a finding that the longitudinal stability of a lifting surface over wavy ground effect is not entirely established. Taking this fact into account, the analysis of the model is proposed for a WIGE craft configuration. A simplification is adopted considering heave motion only in the modelling of oscillation. The simplification is made to thoroughly capture the effect of oscillation toward dynamic stability of the vehicle. To support the model verification, a numerical simulation followed by a semi-empirical design method was adopted to produce aerodynamic data, both in two-dimensional and three-dimensional domains, respectively. The results show that the combination of underpinning parameters, i.e. ride height, frequency and amplitude of oscillation, remarkably influence the aerodynamics. The characteristics in aerodynamics affect the production of stability derivatives and eventually stability behaviour of the chosen configuration. Some patterns in the results are identified but there also some data that show the peculiarity. Thus further investigation is needed.