Experimental and Simulation Investigation of J-Shaped and Kammtail Virtual Airfoils in Small-Scale Horizontal Axis Wind Turbines

Abstract

In this work, the performance of new wind blade designs for small-scale horizontal axis wind turbines (HAWTs) was studied and compared with the performance of a baseline design. The studied designs were J-shaped and Kammtail Virtual Foil profiles. Three J-shaped pressure-side truncation ratios and two KVF truncation ratios were studied. All proposed cases were first investigated in a two-dimensional simulation study to get the lift-to-drag ratio by applying different wind speeds and angles of attack. The baseline design was experimentally investigated. Output power was measured using a digital rotary torque sensor at three wind speeds. The tip speed ratio was calculated after measuring each wind speed's free rotating revolutions. Three wind speeds and experimental TSRs were used in three-dimensional simulations to capture the performances of the proposed cases and compare them with the baseline. The simulation investigation was carried out for lab-scale and scaled cases. The three-dimensional study found that the J-shaped blades enhanced the performance of the HAWTs for both lab-scale and scaled cases. J-shaped blades with a 1/3 opening ratio yielded an average power coefficient enhancement of around 1.56% and 4.16% for lab-scale and scaled cases, respectively. J-shaped blades with a 2/3 opening ratio enhanced the average power coefficient for lab-scale and scaled cases. Furthermore, it was found that the KVF blades diminished the performance for both lab-scale and scaled cases.