Intense levels of noise are generated during the training or during the operations of Unmanned Air Systems (UAS). This is a dual problem due, on one hand, to annoyance of the community during the training flights and, on the other hand, to the risk of an early acoustic detection of the aircraft by the enemy during military operations. For a smart design leading to a quiet and a discreet aircraft, the engine integration of such vehicles is an important characteristic to consider. The potential of optimized engine integration is not exploited enough mainly because noise prediction is less developed. In order to establish a noise shielding database for a validation of acoustic prediction codes, a set of related aeroacoustics shielding tests were carried out. The diffraction studies were performed on the well-known airfoil geometry, namely the NACA0012, in 2D configuration. The experimental tests were carried out in the ONERA F2 wind tunnel using a home-made impulsive reference source. The SPARC source (Source imPulsionnelle AeRoaCoustique) is based on an electrical discharge created by a difference of potential between two electrodes. A strong electric field is generated and accompanied by a dilatation of the heated volume of air between the two electrodes, dilatation immediately followed by a contraction as the air rapidly cools. This phenomenon results in a fluctuation of the local density, which leads to the emission of a high level acoustic wave in all directions. The SPARC noise source was used in the F2/ONERA and the AWB/DLR wind tunnels. The appropriate test source is a key point to successful experimental shielding analysis. The authors present the characteristics of the SPARC source and the improvements done for its implementation in the both wind tunnels. The noise shielding effect results are compared and commented.
