Abstract
Airfoil blades can experience a significant change of angle of attack during operation cycles, which may lead to static or dynamic stall in various applications. It is unclear how elements distributed at the leading edge would affect the aerodynamic performance and stall behaviors. In the present study, a distributed dimples configuration was investigated and compared to a baseline smooth NACA0015 airfoil at low Reynolds numbers. Two- and four-camera, tomographic particle image velocimetry (PIV), and temperature sensitive paint (TSP) techniques were set up to gather flow and surface information near the curved leading-edge surface and to study flow separation. Results suggest that distributed dimples configuration create abrupt separation leading to stall and induce a similar stall compared to the smooth model. However, the stall is induced more abruptly and with different flow patterns. Results show that patterns of separated shear layer at stalled conditions were enhanced by the current configuration. Effect of these structures on the boundary layer transition were also analyzed based on combined tomographic PIV and TSP measurement techniques.
Highlights
Aerodynamic stall causes abrupt decrease in lift and increase in drag, which often leads to unfavorable static or dynamic loading conditions for low-Reynolds-number airfoils
At low Reynolds numbers and angles of attack (AoA), it is often recognized that a “separation bubble promotes laminar to turbulent flow transition at the leading edge, facilitates the turbulent layer reattachment, 3
At low Reynolds numbers and AoA, it is often recognized that a “separation bubble promotes laminar to turbulent flow transition at the leading edge, facilitates the turbulent layer reattachment, of aa low-Reynolds-number low-Reynolds-number airfoil”
Summary
Aerodynamic stall causes abrupt decrease in lift and increase in drag, which often leads to unfavorable static or dynamic loading conditions for low-Reynolds-number airfoils. Active control mechanisms, such as dynamic pitch control [3], plasma actuators [4], and synthetic jets [5,6], have been demonstrated effective in stall control, which enhances airfoil lift generation under large incident angles and increases the overall power production of the rotor blades. This improvement is largely related to the suppression of flow separation under larger angles of attack (AoA) scenarios. It has been found that passive mechanisms/structures can alter the aerodynamics
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
