Wind Tunnel Measurement of Integral Aerodynamic Forces on a Flettner Rotor at Re = 800 Using a Low-Cost Approach

Abstract

The lift and drag forces of a Flettner rotor at a Reynolds number of about 800 are experimentally investigated, resulting in the first force measurements on Flettner rotors at Reynolds numbers being this low. Experiments comprise ratios of circumferential rotor velocity to freestream velocity of 0 ≤ α ≲ 4. The instrumentational facility consists of inexpensive off-the-shelf equipment only. The results show an approximately linear growth of lift with circumferential rotor velocity in the range of 1.5 ≲ α ≲ 3.5, followed by a decrease in lift gradient. While the lift magnitude shows good agreement with available data in the range of linear growth for α ≲ 3, at α ≳ 3 it is considerably higher than in previous measurements with higher Reynolds numbers. The experimental setup is well suited for teaching purposes and the demonstration of both flow phenomena and measurement techniques.