A dual compact model for rotor noise prediction

This paper examines the applicability and robustness of the dual compact thickness noise model for a wide variety of cases. Three major parameters are considered: airfoil, blade planform, and advancing-tip Mach number. The computation results (acoustic pressure time history and spectrum) indicate that generally, dual compact thickness noise is in good agreement with normal thickness noise for all the cases examined in this paper, but the approximation is approximately 24 times faster. The chord length and advancing-tip Mach number have the most impact on the accuracy of the dual compact thickness noise approximation. Therefore, in order to improve the accuracy of the dual compact thickness noise, a scaling factor is proposed to modify the amplitude of dual compact loading vectors for different chord lengths and tip Mach numbers. In addition, loading noise computed by single compact loading and distributed loading is compared in one case. Dual compact loading model is generated by equally dividing the single compact loading at two different chordwise locations. However, dual compact loading result does not have significant advantage over single compact loading in this case.