Affiliations: Tokai University, Graduate School of Engineering,
Course of Mechanical Engineering, 1117 Kitakaname, Hiratsuka, Kanagawa,
259-1292, Japan | Tokai University, Department of Mechanical
Engineering, School of Engineering, 1117 Kitakaname, Hiratsuka, Kanagawa,
259-1292, Japan
Abstract: The present paper describes the flow characteristics around a
rotating grooved circular cylinder with grooves of different depths. The
surface structure of a circular cylinder was varied by changing the depths of
32 arc grooves on the surface. The surface pressure on the cylinder is measured
for the Re range of from 0.4 ×10^5 to 1.8×10^5 and for
rotations of from 0 to 4500 rpm. The drag coefficient of a grooved cylinder
increases as the spin rate ratio α (= rotational speed of the
cylinder surface/uniform velocity) increases for Re > 1.0×10^5.
As the groove depth increases, the drag coefficient of a grooved cylinder is
independent from the spin rate ratio α. The direction of the
lift force of a smooth cylinder is opposite to the Magnus force for Re >
1.0×10^5. However, the direction of the lift force of a grooved
cylinder is the same as that of the Magnus force for all Re >
1.0×10^5. As the groove depth increases, the increase in the slope
of the lift coefficient becomes small. These phenomena are related to the
positions of the flow separation points, which are clarified from the pressure
distribution and flow visualization by the spark tracing method. In addition,
in the present study, the flow around a rotating grooved cylinder is clarified
by flow visualization.
Keywords: Rotating cylinder, Spark tracing method, Fluid force, Pressure distribution
