An Evaluation Testbed for Alternative Wind Turbine Blade Tip Designs

wind turbine;blade design;blade tip;tip aerodynamics;tip design;experimental;performance;analysis;Mechanical Engineering

Gertz, Drew Patrick

University of Waterloo

关键词: wind turbine;    blade design;    blade tip;    tip aerodynamics;    tip design;    experimental;    performance;    analysis;    Mechanical Engineering;   

Others  :  https://uwspace.uwaterloo.ca/bitstream/10012/5941/1/Gertz_Drew.pdf

瑞士|英语

来源: UWSPACE Waterloo Institutional Repository

【 摘 要 】

The majority of present-day horizontal axis wind turbine blade tips are simpledesigns based on historical trends. There is, however, some evidence that varying thedesign of the tip can result in significant changes in performance characteristics suchas power output, noise, and structural loading. Very few studies have tested this ideaon an actual rotating blade and there is much to be investigated. Thus, a project wasdevised to examine experimentally the effect of various tip designs on an operationalrotating wind turbine rotor.A tapered, twisted blade 1.6 m in length was custom designed for use in the UWWind Energy Research Facility using the blade element momentum (BEM) method.A coupling mechanism was designed such that the outer 10% of each blade could beexchanged to evaluate the effect of different tip designs. A set of three blades wasfabricated out offibre-reinforced plastic, while the tips were machined out of maplewood on a CNC milling machine.The blade was evaluated with a standard rectangular tip to establish baselineperformance against which to compare the alternative tip configurations. The three-bladedrotor was tested at shaft speeds from 100 rpm to 240 rpm in wind speedsup to the facility maximum of 11.1 m/s. The rotor was found to have a maximumpower coefficient of 0.42 at a tip speed ratio of 5.3 and a 1.45 kW rated power at awind speed of 11 m/s. The performance was compared to predictions made using theBEM method with airfoil data generated using a modified Viterna method and theAerodas method. While the Aerodas data was capable of predicting the power fairlyaccurately from 5 m/s to 10 m/s, the modified Viterna method predicted the entirecurve much more accurately.Two winglet designs were also tested. Thefirst (called Maniaci) was designedby David Maniaci of Pennsylvania State University and the other (called Gertz) wasdesigned by the author. Both winglets were found to augment the power by roughly5% at wind speeds between 6.5 m/s and 9.5 m/s, while performance was decreasedabove and below this speed range. It was calculated that the annual energy productioncould be increased using the Maniaci and Gertz winglets by 2.3% and 3%, respectively.Considering the preliminary nature of the study the results are encouraging and it islikely that more optimal winglet designs could be designed and evaluated using thesame method. More generally, this study proved that the blades with interchangeabletips are capable of being used as an evaluation testbed for alternative wind turbineblade tip designs.