Analytical Study of the Impact of Solidity, Chord Length, Number of Blades, Aspect Ratio and Airfoil Type on H-Rotor Darrieus Wind Turbine Performance at Low Reynolds Number
Pedram Ghiasi, Gholamhassan Najafi, Barat Ghobadian, Ali Jafari, Mazlan Mohamed
Abstract
The use of wind energy can be traced back thousands of years to many ancient times. Among the tools used for converting wind energy was the vertical-axis wind turbine (vawt). Investigating the performance of this type of turbine is an interesting topic for researchers. The appropriate correlation between the Double Multiple Stream Tube (DMST) model and the experimental results has led researchers to pay distinct attention to this model for vawt simulation. In this study, using the aforementioned model, the appropriate range of important wind turbine design parameters was determined. First, the model outcome was validated based on experimental results and then, the performances of 144 different turbine types were simulated with respect to chord length, number of blades, H/D ratio and airfoil type. Chord length was evaluated at three levels, 0.1, 0.15 and 0.2 m, number of blades 2, 3 and 4, Height to Diameters (H/D) ratio of 0.5, 1, 1.5 and 2, and four types of airfoils, NACA0012, NACA0018, NACA4412 and NACA4418. Simulation was performed at a low Reynolds number (Re ≤ 105) and at four TSRs, 1, 2, 3 and 4. The results show that wind turbines perform best at low TSRs when they have longer chords, more blades, and a higher H/D ratio, but this trend reverses at high TSRs. Among the four types of airfoils evaluated, the NACA4412 airfoils showed a better performance at TSRs 1 to 3.