Horizontal Strut-Arm Optimization Effects on Drag Coefficient
Strut arms contribute significantly to the overall drag in VAWT and reduces the overall power output. Four low drag air foil cross section profiles suitable for strut arm construction were simulated and optimized using the XFOIL 1.0 program. The profile with the lowest simulated drag coefficient, UWI-1, was constructed and tested in an open-circuit suction type conventional non-return laboratory wind tunnel. The flow characteristic was examined experimentally using surface pressure measurements. The results showed that an increase in the Reynolds number from 3.32 x 105 to 9.64 x 105 resulted in a decrease in the drag coefficient from 0.01241 to 0.00984. This is a significantly lower drag coefficient when compared to the nominal value of about 0.4 for cylinders in cross flow within the Reynolds number range tested. The results obtained for the experimental drag coefficient values and the simulated XFOIL were within 10.7%.