Spanwise correlation on a vibrating cylinder near a wall in oscillatory flows
Abstract
Spanwise correlation measurements have been made for a stationary and a transversely vibrating cylinder placed near a wall and exposed to oscillatory flows. The correlation was calculated, based on pressure measurements on the surface of the cylinder. The carriage technique was used in the experiment, to simulate the oscillatory flow. The tests were conducted for three different values of KeuleganCarpenter number, namely 6, 20 and 65, where the Re number was 3.4 × 10^{4} for KC = 6 and 6.8 × 10^{4} for KC = 20 and 65. The corresponding β number range was from 1,050 to 5,700, the lower end of the range corresponding to KC = 65. The tests were conducted for various values of the gap between the cylinder and the wall, normalized by the cylinder diameter, e/D, covering 02.3. The range of doubleamplitude of cylinder vibrations, normalized by the cylinder diameter, 2A/D, was 0  0.7 in the tests. The results indicate that the correlation increases tremendously with the wall proximity, as far as the lift force on the cylinder is concerned. However, the effect of wall proximity appears to be insignificant, when fluctuations in surface pressure, either in the form of organized motion, namely the vortex shedding, in the case of wallfree cylinder or in the form of disorganized wake flow in the case of wallmounted cylinder are considered. Regarding the influence of vibrations on the correlation, it was found that the correlation coefficient first increases with increasing amplitudes of vibrations. However, the increase in the correlation with increasing amplitudes was found not to be as large as in steady currents. The experiments indicate that the correlation coefficient begins to decrease with further increase of the amplitudes. It was found that this occurs for 2A/D larger than about 0.2 for KC = 6 and for 2A/D larger than 0.3 for KC = 20 and 65.
 Publication:

Journal of Fluids and Structures
 Pub Date:
 May 1992
 DOI:
 10.1016/08899746(92)90015U
 Bibcode:
 1992JFS.....6..371K