Effect on drag–thrust transition for flapping airfoil with chordwise flexibility

The objective of the current study is to leverage hereditary flexibility enhance an airfoil's aerodynamic performance. aim understand effect drag reduction by imparting chordwise and thereby increasing thrust generation. done on NACA0015 airfoil examine effects foil dynamical features flapping-based propulsion. experimental work considers pitching oscillations rigid flexible at three amplitudes frequencies in a subsonic wind tunnel for Reynolds number (Re) range 1.2–5.1 × 103. Flow visualization, hotwire anemometer, particle image velocimetry are used flow field. findings demonstrate that alters force parameters efficiently increases For higher value Strouhal (StD), more pronounced. minimum coefficient ratio (Cdr) −3.17 compared −1.55 case foil. result suggests could impart twice propulsion flapping studied. drag–thrust transition occurs 2P wake regime low oscillation frequency. results show undulating enhances around trailing edge, which causes local acceleration fluid. vortex shed closer leading edge because large flap deformation. A region wider stronger envelope velocity jet formed behind case. excess momentum enables generate thrust. deflection meandering suppressed would assist designing wings with thrust-generation capacity improved