COMPUTATIONAL ANALYSIS OF NOISE SOURCES INSIDE THE HIGH SPEED FLOW OVER A BUMP

摘要

The aerodynamic noise sources around the three dimensional bump are studied. In this search, pressure fluctuation on the wall which effects interior noise is searched using ILES. The ratio of the bump diameter (D) and height (H) is D/H=4. In front of the bump, the boundary layer thickness is half of the bump height. Reynolds number based on the bump height was 65000 and the free stream Mach number is 0.1. In flow boundary layer profile is given by using rescaling method and the laminar boundary layer is changed into turbulent boundary layer. Sixth-order-accurate compact scheme is used to represent spatial derivatives and six-order low pass spatial filtering procedure is utilized for removing numerical oscillations. First, instantaneous flow field is discussed. Second, characteristics of time average flow field, such as Cp distribution and stream line topology, are discussed. Third, spanwise velocity fluctuation and sound pressure level on the wall are discussed.