Experimental investigation of an embedded crossflow fan for airfoil propulsion/circulation control

This experimental study examines the feasibility and effectiveness of using a crossflow fan embedded in an airfoil for simultaneous propulsion and circulation control. In an earlier computational fluid dynamics study, results indicated that a 34% thick airfoil equipped with a trailing-edge-embedded crossflow fan can operate stall-free up to 40 deg angle of attack and achieve lift coefficients upward of 6-7. This study seeks to experimentally verify the computational fluid dynamics results and provide further insight into the fan's behavior in providing circulation control to the airfoil. Through flow-visualization techniques, surface static pressure, and wake total pressure measurements, the degree to which the fan can influence the flow is determined. Surface pressure distributions are studied for a wide range of fan operating points and angles of attack, leading ultimately to the calculation of the relative improvement in the airfoil's lift-coefficient curves for the cases studied. Finally, the experimental setup and geometry were reproduced in the computational fluid dynamics package FLUENT for direct comparison with the acquired data. Good agreement between the experimental data and computational fluid dynamics results was found and both confirm the viability of the proposed propulsive/circulation-control airfoil concept.