Application of parametric airfoil design for rotor performance improvement

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Lim, J.W.
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A parametric airfoil design tool, PARFOIL, has been developed in a framework of rotor optimization. The design parameters in PARFOIL include camber and its crest position, thickness and its crest position, leading edge radius, trailing edge camber and its crest position, and boat-tail angle. Upon replacing the standard SC airfoils (SC1095 and SC1094R8) with the advanced RC airfoils (RC(3)-08 and RC(4)-10NL), a sensitivity study with design parameters is performed for UH-60A rotor performance. Camber crest position is found the most influential design parameter. Based on the outcomes in the sensitivity study, new rotor blade configurations are designed and examined for performance improvement. In comparison with the UH-60A standard rotor configuration, it is found that the performance-based best rotor reduces power required by 3.2% in hover, 11.3% at �=0.3, and 13.6% at �=0.4. This demonstrates the ability of PARFOIL to produce better airfoils in the design space. In spite of the performance improvements, the pitch link load of the performance-based best rotor shows an increase of about 8.5% from the UH-60A standard rotor configuration for the UTTAS high-g pull-up condition, which indicates the need to consider pitch link load under high thrust condition as a constraint in the blade design process.