Drag reduction of flat plate normal to airstream by flow control using a rod

Experimental studies on drag reduction of a flat plate normal to airstream were carried out. To control the flow around the plate, a small rod was set upstream of the plate. The chord length of the plate, D, was 50 mm and the diameter of the rod, d, ranged from 2 to 20 mm, and the distance between the axes of the rod and the plate, L/ D, was varied from 1.0 to 2.6. The Reynolds number ranged from 1.9×10 4 to 7.7×10 4. For the case without vortex shedding from the rod at d/ D=0.4 and L/ D=2.0, the maximum reduction of the total drag coefficient is about 20–30% compared to the drag without the rod in the same range of the Reynolds number.