Experimental study on the effect of turning angle on drag and lift forces for various cut angles on spheres

Abstract

Abstract

An experimental study on the effect of turning angle on drag and lift forces for various cut angles on spheres is performed. Five different cut angles on different spheres were applied including: 30°, 45°, 53°, 55°, and 75°.

Drag and lift forces were measured using a wind tunnel force balance and the wind speed was set so that a corresponding Reynolds number of 5.3 × 10⁴ was achieved. Wind turning angle was varied from 0° to 60°.

Experimental results show that, in general, drag and lift forces increase as the turning angle increases. At 0° turning angle, C _d minimum is attained at a cut angle of 53° and is ∼32 per cent less than C _d without cut angle. The maximum C ₁ is attained at a cut angle of 75° for a turning angle of 50° for approximately 0.68. This value of C _1,max is about 855 per cent higher than that of the same turning angle for a cut angle of 30°. At a particular turning angle, lift attains a maximum and beyond that turning angle-drag and lift forces decrease. Minimum value of drag and lift forces reached at the cut angle of 30° for all turning angles.