Aerodynamic Design and Numerical Assessment of a 1.5 kW Helical Vertical-Axis Wind Turbine Using DMST and Three-Dimensional CFD

Helical vertical-axis wind turbines are well suited to small-scale distributed generation because they need no yaw mechanism and can operate effectively in changing wind conditions. However, their aerodynamic design requires comparing configurations without relying solely on computationally expensive simulations. This article describes the design and numerical evaluation of a helical rotor for a vertical-axis wind turbine coupled to a 1.5 kW generator. It combines wind resource analysis, rotor sizing, and a double multiple streamtube (DMST) model, and compares the results with computational fluid dynamics (CFD) simulations. The resulting three-bladed rotor, designated DU-H-18, uses the DU-06-W-200 airfoil and a 63° helix angle. The DMST model predicted a maximum power coefficient of 0.4071 at a tip-speed ratio of 2.5, whereas CFD yielded a maximum of 0.3806 at a tip-speed ratio of 3, with torque and drag coefficients of 0.1269 and 0.0326, respectively. At the common operating condition near λ = 3, the predictions obtained with the selected DMST and CFD numerical settings differed by approximately 3%. However, a three-level temporal-resolution assessment using Δt = 0.005, 0.0025, and 0.00125 s showed that the CFD integral torque remained sensitive to temporal discretization. Therefore, this difference of approximately 3% is interpreted as conditional on the selected numerical settings rather than as demonstrated agreement between time-step-independent solutions. DMST nevertheless captures the overall performance trend and can support preliminary geometric assessment, whereas CFD remains necessary to characterize viscous losses, flow separation, blade–wake interactions, and three-dimensional vortex structures.