CAA fundamental and Application

Duck Joo Lee, In Cheol Lee and Chi Hoon Cho

Korea Advanced Institute of Science and Technology

373-1 Guseong-dong, Yuseong-gu, Daejeon, 305-701, Korea

Tel: +82-42-869-3716, djlee@kaist.ac.kr

Computational Aeroacoustic (CAA) deals about capturing radiated acoustic quantities generated from flow fluctuations numerically. In general, the amplitude of acoustics is less than 4th order of the flow. Therefore, a higher order scheme, such as compact scheme, is employed to capture the acoustic and flow at the same time. To minimize the numerical phase error in the radiated acoustics, the coefficients of the high order scheme are optimized to have minimum dispersion error. Several high order high resolution schemes are compared in the point of numerical wave resolutions. The high order optimized compact schemes are applied in the acoustic from the cylinder, cavity tone and screech tone in the supersonic jet. The result of cylinder shows that the optimized compact scheme yields precise results. Cavity tone and Screech tone are generated due to the feedback between flow and acoustic wave. It is recognized that the period is determined by the time required for the flow convection in one direction, the time required for the acoustic propagation in the other direction and the time for phase shift depending on the flows and mode. But the cause of the phase shift and the correctness of the theory have not been clearly explained so far. results of cavity tone and screech tone shows feedback phenomena. Additionally, other effective methods for numerical analysis of incompressible flow noise are addressed and discussed.