Experimental investigation on drag coefficient reduction due to tripping wire on a cylinder

Authors

1 Graduated M.Sc.

2 hakim sabzevari university

Abstract

An experimental investigation is conducted in the wake of a circular cylinder with two tripwires attached at angle of 140 and 40 degrees measured from the forward stagnation point at Reynolds numbers, Re = 30000. The tripwire diameter is 0.5, 1, 1.5 mm. The effects of the tripwires on drag reduction, mean velocity profile and velocity defect and half width, turbulence intensity profiles and Strouhal number have been examined. The results reveal that for Re=3000, there exits optimum case where the drag coefficients acting on the cylinder all reach some of the drag coefficient of a plain cylinder. At the optimum case the drag coefficient of cylinder is reduced for two-wire cylinder with two different diameters. The results reveal that when we get far from cylinder, the procedure of changes of the peak of mean velocity (w0), and peak of turbulence intensity profiles decrease–increase and increase–decrease, respectively. Also the results of experiment are shown that with a plain cylinder the values of peak of turbulence intensity profiles and velocity defect (w0) are generally decreased compared with those values for tripping wires cylinder.

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