Supercritical Reynolds number experiments on a freely rotatable cylinder/splitter plate body

The behavior of a circular cylinder with attached splitter plate, under conditions where the entire cylinder/splitter plate body was free to rotate about the cylinder axis, has been studied experimentally as Reynolds number was increased through the critical value (laminar boundary layer separation replaced by turbulent boundary layer separation farther downstream). As in previous experiments (at lower Reynolds numbers), it was found that the plate did not align itself with the free stream, but instead rotated to some off-axis equilibrium angle, θ. For plates with splitter plate length, L, less than one cylinder diameter, D, θ dropped very quickly to some minimum value in the transitional Reynolds number range, then slowly increased toward some new supercritical value, which in all cases was smaller than that in the subcritical range. For cases with L/D≳1, however, in the transitional Reynolds number range, the splitter plate overshot the centerline and commenced oscillating between extremes on either side. At supercritical Reynolds numbers, for cases with L/D≤2, a new equilibrium angle eventually reestablished itself on one side or the other; but for cases with L/D≥2.5, the cylinder/splitter plate body continued to oscillate between extremes on either side, even at the highest Reynolds numbers tested.