1COMPARISON OF FULL-SCALE XV-15 BLADE-VORTEX INTERACTION NOISE CALCULATIONS WITH WIND TUNNEL DATA

Results from the TRAC acoustic prediction system were correlated with data from a test of an isolated full-scale XV-15 rotor in the NASA Ames 80- by 120-Foot Wind Tunnel. The airloads calculation provided by the original CAMRAD.Mod1 code in the standard TRAC system was exercised with several high resolution options, including the FPXBVI CFD code. In addition, the more recent CAMRAD II code was run in place of the original CAMRAD.Mod1. The CAMRAD II code, with a multiple trailer wake model yielding airloads at 3 degree azimuthal resolution, provided excellent correlation with measured BVI pulse amplitude, but less so for pulsewidth. There is indication that better results may be obtained with higher resolution airloads. Notation. c speed of sound CT rotor thrust coefficient (shaft axes) Mtip blade tip Mach number r/R microphone radial distance from hub rinner blade root cutout radius R blade radius a s rotor shaft angle (positive aft) b 0, b 1c , b 1s blade flap components f microphone elevation angle (positive down from rotor plane) m advance ratio r air density s rotor solidity q 0, q 1c , q 1s blade pitch components y azimuth angle (positive conterclockwise from downstream