Vibrational characteristics of sphere model installed in wind tunnel test section

Abstract

The vibrational characteristics of a sphere model installed in a wind tunnel test section were quantitatively investigated using a noncontact laser vibrometer. The sphere was supported by two fine wires passing perpendicularly through the center of the model in an Xshape. Each end of the wire was fastened firmly to the frame of the test section with a secure turnbuckle. This fixation method was evaluated by laser vibrometry measurement of the vibration of the sphere and by spectral analysis. The maximum displacement of the sphere was found to be less than 30 nm with the characteristic frequency on the order of hundreds of kilohertz. The effects of the vibrational displacement and frequency of the model were negligible considering the model dimensions and the shedding frequency of the sphere wake.