Fuselage-Induced Velocity Model for LRTA, RTA, and HART Fuselages

In order to make the aerodynamic fuselage-rotor interference effects available to comprehensive rotor codes, a simple analytical model of the fuselage-induced velocities is developed here for the following bodies used in wind tunnel experiments: • the Large Rotor Test Apparatus (LRTA), • the Rotor Test Apparatus (RTA), and • the Higher Harmonic Control Aeroacoustic Rotor Test (HART). While the first two are used in the National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames Research Center, California; the third one is used by DLR in the large low-speed facility of the German-Dutch wind tunnel in the Netherlands. The fuselage-induced velocity model is based on parameter identification of isolated fuselage-induced velocity data (computed by means of computational fluid dynamics, CFD) and is intended to be generic enough to be used for real helicopter fuselages as well. The accuracies obtained in reproducing the CFD data show a remaining average error of less than or equal to 5% of the peak-to-peak induced velocity range; which is considered sufficient for comprehensive code analysis.