Hover Predictions on the S-76 Rotor with Tip Shape Variation Using Helios

摘要

High-resolution, time-accurate computational fluid dynamics validation of a 9.34 ft, four-blade, Mach-scaled S-76 rotor in hover is performed using the U.S. Department of Defense Computational Research and Engineering Acquisition Tools and Environments-Air Vehicles Helios software. The effect of blade tip shape variation is studied for three tip shapes: rectangular, swept tapered, and swept tapered anhedral. The effect of tip Mach number is studied for the swept-tapered tip. Computed results include rotor performance, blade airloads, and tip-vortex strength and position. The performance predictions are compared against the test measurements and good agreement is obtained. Compared with the swept-tapered tip, the rectangular blade incurs compressibility losses near the tip. The addition of anhedral to the swept-tapered tip improves performance as a result of redistribution of thrust.