Experimental investigation on effect of partial flexibility at low aspect ratio airfoil – Part I: Installation on suction surface

Effects of flexible membrane mounted over suction surface NACA 4412 airfoil were experimentally investigated at Reynolds number 5x104 and low aspect ratio (AR=1) in this paper. The smoke-wire visualization method has been performed for flow to demonstrate phenomena as laminar separation bubble (LSB), leading edge z/c=0.4 tip vortices z/c=0.1. Values velocity, stress turbulence statistics measured by means a constant temperature anemometer (CTA) system. Results experiment revealed that size height LSB formed along lower angles attack such α=8° was mitigated. Moreover, stall phenomenon result boundary layer apparently postponed higher attack. Velocity value increased, whereas values Reynold turbulent kinetic energy decreased with reduction amount fluctuations flow. Consequently, using allowed the be mitigated or extinguished, resulting exhibition more stable characteristics.