Title   name
KSIAM 2006 Annual Meeting
  Speaker   Yu, Yung Hoon  
  Date 2006-11-24
  Place 건국대학교
  File  의 1 번째 Real Media 동영상입니다. 의 1 번째 강연자료입니다.
Abstract : A generalized singularity description of an inhomogeneous wave field for moving surfaceboundary conditions in arbitrary motion is presented and applied to nonlinear wavepropagation and acoustics of rotors in high speed. A nonlinear transonic aerodynamicequation is derived for understanding basic impulsive noise generating mechanisms of rotorsin high speed. This equation includes the high-order mathematical singularities in thenonlinear transonic equation in a rotating frame, which is an integral equation with no simpleclosed-form solution available. The governing equation for high-speed impulsive rotor noiseis formulated with a nonlinear velocity potential and this equation governs how local shockwaves propagate away from rotating blades. This equation is also useful to explain thephenomenon of delocalization, which is a sudden change of propagation of nonlineartransonic shock waves on a blade to a far-field at a certain Mach number. This delocalizationphenomenon is validated with experimental results and explains one of the unsolved acousticpropagation problems. The important aspect of this phenomenon is an introduction of anonlinear sonic curve concept with respect to nonlinear wave propagation. The effect of thedelocalization Mach number on the nonlinear wave propagation of high-speed impulsive rotornoise is investigated.