2007 Volume 2 Issue 2 Pages 278-292
To provide reliable validation data for computational aeroacoustics methods that predict bluff-body sound, the far-field sound pressure and fluctuating surface pressure were measured in detail for a simplified mock-up model of an automobile door mirror (a quarter-section sphere mounted on a half-circular cylinder placed on a flat plate). The surface flow on the model was visualized using an oil flow method. The Reynolds number based on the upstream uniform wind velocity and the diameter of the half-circular cylinder was varied from 1.4×105 to 2.4×105 for model yaw angles of 0 and 15 degrees. The pressure fluctuations on the model surface and flat plate indicated the existence of large-scale vortical motion with a non-dimensional frequency, calculated on the basis of the model width and the free-stream velocity, of 0.16. The frequency spectra of the sound pressure fluctuations had a weak peak apparently due to the large-scale vortical motion. However, unlike the flow around a two-dimensional circular cylinder, the peak was not intense enough to alter the overall level of the sound radiated from the model. When the model was rotated 15 degrees, the power spectra of the sound pressure increased in the non-dimensional frequency range between 1 and 2.
