BEM theory analysis of a small biomimetic HAWT

• Main Author: Damirez, Von Eric A.
• Format: text
• Language: English
• Published: Animo Repository 2021
• Subjects: Horizontal axis wind turbines; Horizontal axis wind turbines—Blades; Wind turbines—Aerodynamics; Mechanical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etdm_mecheng/2; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1000&context=etdm_mecheng
• Institution: De La Salle University

A small biomimetic horizontal axis wind turbine (HAWT) with tubercles was analyzed using the Blade Element Momentum (BEM) Theory. Calculation frameworks based from the Original BEM Theory and three (3) other brake state models (Wilson-Walker Method, Glauert’s Empirical Formula, and Buhl’s Theory) were used in the prediction of the power output and power coefficient. The results were then evaluated and compared to the actual wind tunnel test results presented in the literature. The Buhl’s theory was considered to be the most accurate method in predicting the power output since it had the lowest mean absolute percentage difference (MAPD) and mean absolute deviation (MAD), with values of 17.21% and 1.63 Watts respectively. The Wilson-Walker Method provided the closest prediction of the power coefficient at λ=4.06, showing only a percentage difference equivalent to 0.47%. A maximum power coefficient of 0.28 at λ=5.10 was predicted by the Original BEM Theory. The Wilson-Walker method, Glauert’s empirical formula, and Buhl’s theory recorded close values of maximum power coefficients of 0.24, 0.23, and 0.23 respectively. This only proved that the small biomimetic HAWT’s power coefficient could still be increased if the tip speed ratio was also increased further to a certain point. The axial and tangential induction profiles both produced curves with wavy patterns similar with that of the chord length distribution. This resemblance meant that the variation in chord lengths and their arrangement in a wind turbine blade both had a significant role on the induction curves calculated by the BEM Theory. Specifically, the tangential induction curve generated by the original BEM theory had the most significant similarity with the chord length distribution on a small HAWT with tubercles, based from the correlation coefficient of 0.9890. This relationship opened up avenues for future studies. Comparison of the straight and biomimetic blade also confirmed that the addition of tubercles on a wind turbine blade posed a disadvantage in the aerodynamic performance of the small HAWT.