Aerodynamic performance analysis of two new types of helical blades for vertical axis wind turbines

For aerodynamic performance improvement, a helical blade vertical axis wind turbine (VAWT) with a symmetric structure is proposed. Using NACA0018 as the base airfoil, three-dimensional numerical simulations of the symmetric helical blade VAWT and a helical blade VAWT are performed using the shear–stress transport k–ω model. The aims is to comprehensively explore the correlation and influence between their wind energy utilization coefficients, single-bladed transient moment coefficients, and flow field characteristics under different wind field conditions. Furthermore, the blade cross sections at positions of 0.3H, 0.5H, and 0.7H are symmetrized and subsequently numerically simulated in terms of both global and local symmetries. The symmetrical blades provide smooth and significant average moment coefficients under low tip speed ratios (TSRs) and similar average moment coefficients under high TSRs. The global symmetry helical blade VAWT (GS-helical blade VAWT) exhibited the best performance. Compared to the helical blade VAWT, the average value of the total moment coefficient afforded by the proposed GS-helical blade VAWT is 19.13% higher at TSR = 1 and similar at TSR > 1.9. In conclusion, the proposed symmetric helical blade VAWT exhibits improved aerodynamic performance and can be practically employed.