The characteristics of vortex wakes of rectangular prisms, with and wihtout forced osicllation, were experimentally investigated, as placed in different uniform turbulent flows. The experimental parameters were the turbulence intensities and length scales of the uniform turbulent flows and the depth-to-width ratios and vibrating frequencies, with fixed amplitudes, of the rectangular prisms. Measurements were taken on the lateral pressure and base pressure of the prisms, the point velocity in the wake, and the phase angle between lateral pressure and body displacement. The pressure coefficients (-CP, -Cpb• Cp', C~b) are much greater when the oscillating cylinder is in lock-in range and reach peak values at resonant frequencies in a uniform flow. High turbulence intensity weakens the vortex shedding, thereby decreasing the pressure coefficients and peak values of the spectra. Increasing the turbulent length scale causes the pressure coefficients to increase. The critical depthto- width ratio is found at HID=.6, while decreasing in this ratio results owing to increases in turbulence intensities.
關聯:
Journal of the Chinese Institute of Engineers=中國工程學刊 20(6), pp.615-622
