Abstract
Control of the dynamic stall process of a NACA 0015 airfoil undergoing periodic pitching motion is investigated experimentally at the NASA Ames compressible dynamic stall facility. Multiple microjet nozzles distributed uniformly in the first 12 % chord from the airfoil’s leading edge are used for the dynamic stall control. Point diffraction interferometry technique is used to characterize the control effectiveness, both qualitatively and quantitatively. The microjet control has been found to be very effective in suppressing both the emergence of the dynamic stall vortex and the associated massive flow separation at the entire operating range of angles of attack. At the high Mach number (M = 0.4), the use of microjets appears to eliminate the shock structures that are responsible for triggering the shock-induced separation, establishing the fact that the use of microjets is effective in controlling dynamic stall with a strong compressibility effect. In general, microjet control has an overall positive effect in terms of maintaining leading edge suction pressure and preventing flow separation.
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Acknowledgments
This work was supported by a grant from NASA Ames, monitored by Dr. G. Yumauchi; we are grateful for this support. We also thank additional support and technical advices provided by Dr. C. Tung of US Army Aero flight dynamics Division and Dr. J. C. Ross and Dr. R. D. Mehta for allowing the use of the FML CDSF.
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Beahan, J.J., Shih, C., Krothapalli, A. et al. Compressible dynamic stall control using high momentum microjets. Exp Fluids 55, 1813 (2014). https://doi.org/10.1007/s00348-014-1813-6
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DOI: https://doi.org/10.1007/s00348-014-1813-6