Separation control of a NACA 4412 with 25° sweep at high Reynolds numbers using pulsed-jet actuators
Résumé
Boundary-layer separation at large Reynolds numbers over swept wings remains a challenging phenomenon to either replicate in well-controlled laboratory experiments or predict in full-scale applications. The present work reports the aerodynamic performances of a wind-tunnel model based on a NACA 4412 airfoil with a sweep angle of 25◦ at Reynolds number up to 106. In addition, A flow-control strategy based on bi-stable fluidic oscillators is presented where the pulsed jet actuators (PJA) are capable of reaching frequencies of several kHz. This novel setup aims at improving the authority of the control while minimising the power input by the actuators.
To this end, several actuators were designed and tested to determine the best configuration. In this paper, we provide a summary of the results obtained for the best actuator and demonstrate net gains as high as 18% near stall, for values of the momentum coefficient as low as 2.5 × 10−4. The success behind this strategy resides in the low-speed high-mass-flow-rate provided by the design of the actuators which compensate for the mass and
momentum deficits in the boundary layer and delay efficiently separation. This study underlines the potential for upscaling this strategy to the full scale where the flow injected for the control is generally limited.
Origine | Fichiers produits par l'(les) auteur(s) |
---|