In this work the propagation characteristics of acoustic waves due to the interaction between a vortex and a helicopter airfoil were computed for a wide variety of methods, ranging from Linearized Transonic Small Disturbance to Thin-layer Navier-Stokes. The analysis of the data from these methods showed that the accurate calculation of the acoustics required a computational method that not only accurately calculated the aerodynamics on the airfoil, but also properly preserved and propagated the wave as it left the surface. This resulted in improvements to the Transonic Small Disturbance formulation for transonic airfoil-vortex interactions. Several post-processing techniques were developed to display the most important information from the computations.; The Euler equations were found to be the most effective for calculating typical transonic airfoil-vortex interactions. Thus, they were utilized to study the effect of transonic flow on the formation process of the acoustic wave, resulting in significant new insight. Next, various parameters were studied. It was shown that in the linear subsonic regime the strength of the propagating wave varies with the sixth power of the Mach number; while, in the non-linear transonic regime this power is smaller. It was also shown that in the transonic regime, the sign of the vortex was very important; suggesting that in the transonic regime one should avoid situations which results in clockwise vortices passing above the airfoil.; The most important parameters governing transonic airfoil-vortex interaction noise were the Mach number, the vortex miss-distance, vortex strength and the sign of the vortex. Surprisingly, the airfoil shape and shock wave motions had relatively little effect on the transonic airfoil-vortex interaction noise.
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