Akademik Veri Yönetim Sistemi
5th International World Energy Conference, Kayseri, Türkiye, 12 - 13 Aralık 2025, ss.1185-1190, (Tam Metin Bildiri)
The aerodynamic performance of Vertical Axis Wind Turbines (VAWTs) is significantly affected by flow separations and instabilities, particularly at low Reynolds numbers. In this study, the formation and behavior of the Laminar Separation Bubble (LSB) on finite and infinite wing models possessing the NACA 4415 airfoil and wing were investigated experimentally. The primary objective of this research is to elucidate the aerodynamic differences between the finite wing, where three-dimensional flow effects are present, and the infinite wing, representing idealized two-dimensional flow, through the LSB mechanism. Experimental tests were conducted at three different Reynolds numbers (75,000, 100,000, and 150,000) within an angle of attack range of 0 to 16 degrees. The surface oil flow visualization technique was utilized to observe the flow structure on the wing surfaces. The acquired visual data were analyzed using Python-based image processing algorithms to detect flow separation and reattachment points, enabling quantitative assessment. The results reveal that the LSB effect is particularly distinct at a Reynolds number of 150,000. While early stall is observed at lower Reynolds numbers, the behavior of the LSB changes significantly at higher Reynolds numbers. Specifically, at Re=150,000, it was observed that the LSB progressively moves towards the leading edge and diminishes in size up to an angle of attack of 12 degrees. Beyond 12 degrees, the bubble completely disappears. These findings corroborate the critical role of Reynolds number and wing finiteness in the design of vertical axis wind turbines.