Effect of Blade Tip Sweep on Flutter in Small-scale Wind Turbine Rotors

Wind turbines and wind power are becoming more important as the need for renewable sources of energy increases. Wind turbines are efficient and environmentally friendly, but they need to be constantly studied to improve safety and performance. Flutter is a particularly important concern for wind turbines, as it can cause fatigue and subsequent failure in turbine blades. Flutter is the vibration of the blade caused by external loads and high angular velocities. This report analyzes the flutter effects of small scale wind turbine blades. The rotor was made of acrylic and was rotated with a motor. The angle of sweep of the blade tip was varied and the rotations per minute (rpm) were measured. Sweep angles of 0 degrees (control), 5 degrees, 10 degrees, and 15 degrees were tested. The rpm at which flutter and early onset flutter occurred was recorded. Early onset flutter is the vibration suggesting the beginning of flutter and is used as an indicator that flutter will soon occur. This report aims to determine if there is a correlation between the angle of sweep and the rpm at which the blade flutters. From the data collected to date, evidence suggested a slight trend of a decreasing rpm “speed limit” at which flutter occurred in the blade for higher degree sweeps (15 degrees), but overall there was not a strong correlation between sweep angle and the rpm at which flutter was evident. Further testing will be performed to confirm or deny this trend, as well as to determine if there is a strong correlation at all