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The breakaway of the flow from solid surfaces is defined as stall, which cannot hold onto the surface based on the positive pressure exposure due to geometric or external factors. Flow separation (stall) is the most critical concept affecting the performance of the aircraft. Hence in this study, it is aimed to change the shape of the airfoil profile during the flight to obtain maximum performance at different angle of attack values. 2D computational fluid dynamic analysis is used in this study based on NACA 4412 airfoil profile. In order to achieve higher aerodynamic performance at different angles of attack during flight, two different airfoil profiles were obtained (NACA 4412_1 and NACA 4412_2) by modifying the NACA 4412 airfoil profile and the aerodynamic performances of the original NACA 4412 airfoil profile with the modified airfoil profiles were compared. Analyses were performed between 0° and 23° angle of attack values to carry out the comparison. Drag coefficient, lift coefficient, and flow separation as the performance parameters were investigated. At the end of the study, it was determined that the NACA 4412 airfoil profile angle (a) between 0° and 12°, the NACA 4412_2 airfoil profile angle (a) between 12° and 17°, and the NACA 4412_1 airfoil profile for angle of attack values higher than 17° were suitable for maximum aerodynamic efficiency. [ABSTRACT FROM AUTHOR]

The breakaway of the flow from solid surfaces is defined as stall, which cannot hold onto the surface based on the positive pressure exposure due to geometric or external factors. Flow separation (stall) is the most critical concept affecting the performance of the aircraft. Flow separation can also be defined as boundary layer separation. The boundary layers that develop on the upper and lower surfaces of the airfoil do not separate at small angles of attack. Stall is an undesirable situation which causes a sudden reduction in the lift generated by the aircraft wing when the critical angle of attack is reached or exceeded. Flow separation on an airfoil surface can observed at different critical angle of attack values related to the aerodynamic design of the airfoil profile. Hence in this study, it is aimed to change the shape of the airfoil profile during the flight to obtain maximum performance at different angle of attack values. 2D computational fluid dynamic analysis is used in this study based on NACA 4412 airfoil profile. In order to achieve higher aerodynamic performance at different angles of attack during flight, two different airfoil profiles were obtained (NACA 4412_1 and NACA 4412_2) by modifying the NACA 4412 airfoil profile and the aerodynamic performances of the original NACA 4412 airfoil profile with the modified airfoil profiles were compared. Analyses were performed between 0° and 23° angle of attack values to carry out the comparison. Drag coefficient, lift coefficient, and flow separation as the performance parameters were investigated. At the end of the study, it was determined that the NACA 4412 airfoil profile for 0° < α < 12°, the NACA 4412_2 airfoil profile for 12° < α < 17°, and the NACA 4412_1 airfoil profile for angle of attack values higher than 17° were suitable for maximum aerodynamic efficiency. [ABSTRACT FROM AUTHOR]

In this study, a new algorithm has been developed for Design Optimization of composite plates using Tsai- Wu criteria. Von-Mises stress criteria is used as design variable for the stress based Design Optimization problems. It is used to understand the effect of combined stresses on the isotropic materials. However, Von- Mises stress analysis is not appropriate for anisotropic composite materials. To define the strength of composite materials, maximum stress, maximum strain, Azzi Tasi Hill and Tsai-Wu criterias are used. In this study, failure index was used as design criteria and Tsai-Wu criteria was used to calculate this value in the optimization algorithm. Topology optimization, which is used for mass and shape optimization on structures, is a design tool. In this study, a new algorithm has been developed for topology optimization of composite materials. By using this algorithm, common geometric models and different fiber angles have been investigated. Nearly 50% mass reduction have been obtained by using the developed algorithm. [ABSTRACT FROM AUTHOR]