The Effects of Tilt on a Savonius Rotor Exposed to a Turbulent Flow Regime

Results are presented of measurements of the performance of Savonius rotor type instrumentation being used for high resolution current profile studies in the Straits of Florida. The instrumentation housing is designed to hold the rotor horizontally during a profile measurement of the water column, but internal and external forces act to displace the profilers from their designed horizontal axis and introduce errors into their measurement of current velocity. The necessity for determining the occurrence and magnitude of these errors prompted this investigation into the effects of tilt on a Savonius rotor exposed to a turbulent flow regime, plus the development of an instrument to measure rotor inclination. Although the rotor tested was not a true Savonius rotor and actual velocity profiles are not uniform, the results are believed to be applicable to similar instrumentation. Significant differences in tilt effects between the measurements in this study and previous results were observed. Recommendations for reexamination of housing designs and careful calibration under controlled conditions are included.