Title: BYOE: Comparison of Vertical- and Horizontal-axis Wind Turbines
Abstract: Abstract Wind turbine technology provides an opportunity to measure a number of experimental quantities, including wind speed, power generated, and rotational speed. An experiment using scale model wind turbines in a wind tunnel was developed for a junior level course in Measurements and Analysis at ___________ University. The primary goals of this experiment are: 1. To learn how to measure wind speed using Pitot tubes and anemometers. 2. To measure rotational velocity using non-contact methods 3. To compare vertical and horizontal axis wind turbines in terms of power produced as a function of wind speed and load on the generator. 4. To demonstrate key wind turbine concepts such as power generated from wind, power coefficient, and tip speed ratio. The experiment was conducted in a small scale wind tunnel that had been designed and built by senior undergraduate design students. Teams of 3-4 students were given either a three bladed horizontal axis wind turbine or a Savonius vertical axis wind turbine. The three-bladed turbine was taken from a commercially available kit and modified using custom 3D printed parts. The Savonius wind turbine was completely designed and 3D printed in house. In each lab section, each group tested one of the turbines, then shared the data with the other groups. During testing, the tunnel fan speed was increased in increments. At each fan speed increment the group varied the electrical load on the generator while measuring wind speed, power, and rotational speed. Wind speed downstream of the wind turbine was measured using a Pitot tube and a differential pressure transducer. Wind speed upstream of the wind turbine was measured using an anemometer. The power generated by the wind turbine and the temperature of the air were measured using a Vernier™ Energy Sensor and Temperature Probe, connected to a Vernier™ SensorDAQ. The rotational speed of the turbine was measured using a non- contact optical tachometer and an oscilloscope. At the end of the experiment, students had enough data to compare vertical and horizontal axis wind turbines in terms of power generated, power coefficients, and tip speed ratio. Students were be able to examine the relationship between load on the generator and turbine behavior. During the analysis portion of the lab report, students were also asked to compare the behavior, uncertainty, and accuracy of the various sensors. In a post lab survey students rated the first iteration of this lab as more interesting than the previous wind tunnel lab, which had measured drag on a model car. Students demonstrated increased proficiency in calculating instrument uncertainty and increased understanding of wind tunnel concepts between the pre-lab homework and the post-lab report. Some frustration was noted due to unexpected wind measurements from the anemometer. Future terms will concentrate on minor improvements to the instrumentation and connection of the wind turbines to the wind tunnel.