The application of advanced beamforming techniques for the noise characterization of installed counter rotating open rotors

This paper reports on the results of a series of aeroacoustic measurements of a counter rotating open rotor (CROR) installed on a 1/7 scale model of an advanced regional aircraft design. The tests were conducted in a large low speed wind tunnel for a variety of aircraft geometries, angles of attack and flow speeds. Data were acquired on three far field beamforming arrays. The study attempts to characterize the installed CROR noise source through the application of several beamforming techniques applied to each individual array and to a global array of the three arrays in combination. Although some results have been achieved in this preliminary study, there are also drawbacks and limitations of the beamforming processes for the case of model with CRORs, therefore a deeper investigation will be necessary. This work has been conducted as part of the European Clean Sky funded WENEMOR project which will be completed in August 2013, the testing phase of which was completed in May 2013.