円弧型溝付回転円柱まわりの流動特性(流体工学,流体機械)

概要

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The drag and lift coefficient characteristics of rotating cylinder with arc grooves is investigated. The circular cylinders with grooves have thirty-two arc grooves of different depth on the cylinder surface. Pressure of the cylinder surface is measured with the Reynolds number Re=(0.4〜1.8)×10^5, and rotation of 0〜4500rpm. The drag and lift coefficients are calculated from pressure distribution. At Re=0.4×10^5, the drag coefficient C_D of smooth cylinder is constant until the spin rate ratio α(α=rotating speed/uniform flow)=0.6, and C_D decreases afterwards at 0.6<α<1.0. As Reynolds number increase, this decreasing part shift to low α side. In the case of cylinder with grooves, the decreasing part of C_D exists only in Re=(0.4〜0.8)×10^5 (subcritical, critical region of stationary condition), and C_D has monotonic increase at Re>1.0×10^5. As groove depth becomes deep, C_D becomes constant value as α increase. The lift coefficient C_L of smooth cylinder increases as α increase. However, C_L decreases to the minimum value as α further increase and C_L increases again with the increase of α, C_L indicated negative lift in Re>1.0×10^5. C_L of cylinder with grooves become monotonous increases tendency in Re>1.0×10^5. As groove depth becomes deep, the increasing gradient of C_L becomes small.
一般社団法人日本機械学会の論文
2005-03-25