Novel Controlled-Velocity Wind Turbine Testing Apparatus to Simulate Turbulent, Non-Return Flow

This paper presents the work done by the authors to analyze the method of performance characterization of a 100W scale vertical axis wind turbines using a controlled-velocity test apparatus. The design of the power transfer system containing a gearbox and generator requires test data to determine the peak and operating range of wind speed, corresponding to RPM and torque. Multiple methods of turbine testing were considered, including in situ, wind tunnel, and control-velocity. Controlled-velocity, a method where the turbine is moved through a fluid, was selected based on lack of test location wind speeds or access to a wind tunnel of sufficient size. The test apparatus is designed to be effective for VAWT turbines of a diameter range from 1.45 to 4.2 meters in a wind velocity range of 1 to 17 m/s. This covers a Reynolds number range between (2.5 × 10^5 < Re < 4.2 × 10^6). A change from previous control-velocity test apparatus is the use of a separate truck and trailer compared to a flatbed truck, which allows greater distance between the truck cab and the turbine, to decrease any flow interference of the cab. This previous work and testing has shown to be a valid test method in that the turbine is in similar turbulent conditions as near the ground and buildings which the turbine is designed for. The main advantage of this test apparatus is the ability to test turbines in a region with low average wind speeds and minimum infrastructure.