Discussion: “Experiments on Flow About a Yawed Circular Cylinder” (Smith, R. A., Moon, Woo Taik, and Kao, T. W., 1972, ASME J. Basic Eng., 94, pp. 771–776)

Abstract

certainly outside of the separated shear layer a t a position above boundary layer separation. Bloor also detected waves outside of the separated layer. The entire sequence of the development of transition waves and subsequent turbulence is elaborately outlined by Bloor, and we find the same qualitative behavior when the cylinder is yawed. Typical oscilloscope traces are noted in Fig. 9. These data are downstream of the first appearance of transition waves, and the transition wave is superimposed on the lower frequency vortex shedding wave. The transition wave frequency was measured by storing a 10 to 100 millisec waveform in an oscilloscope and simply counting the wave cycles over a known time interval. At A = 0 this was generally satisfactory and it gave results of frequency versus Reynolds number consistent with Bloor's data, as noted in Fig. 10. The variation in the data obtained at any Reynolds number is large and the frequency measurement is subject to significant variation, especially at the lower frequencies, as noted by the bars about the data points in Fig. 10. The data at A = 0 degrees do follow the established result for separated shear layers tha t transition wave frequency is proportional to U' where U is the characteristic velocity. The free-stream velocity is taken to be characteristic of the problem of the unyawed cylinder.