GARTEUR activities on acoustical methods and experiments for studying on acoustic scattering

This paper deals the activities conducted in the GARTEUR Action Group HC/AG-24 to address the noise scattering of helicopter rotors in the presence of the fuselage. The focus of the Action Group is on the development and the validation of numerical prediction methods and establishing an experimental data base for numerical validations. The numerical methods include boundary element method for solving the Helmholtz equation and computational aeroacoustic method for solving linearized Euler equations. The test activities are conducted in the DLR Acoustic Wind Tunnel in Braunschweig. In the current paper, the results from the numerical simulations, the wind tunnel tests as well as numerical and test comparisons are addressed. The test configurations include the sphere, the sphere with sting support and a finite NACA0012 wing (thanks to share data with a NATO STO group). The acoustic predictions of the scattering by spheres will be compared with the analytic solution to address the influence of the sphere support systems at different wind speeds. The acoustic predictions of the scattering by NACA0012 wing will be analyzed and compared to available test results for different source locations and frequencies.