Small wind turbines operate under low Reynolds number conditions, where improving aerodynamic efficiency becomes crucial due to the adverse inflow characteristics. This study systematically investigates the isolated effect of a broad range of inflow turbulence intensities on the aerodynamic performance of a NACA2414 airfoil at a Reynolds number of 10 5 using two-dimensional finite volume Unsteady Reynolds-Averaged Navier-Stokes simulations. The computational domain was discretized as a structured grid and a Realizable k-ɛ model was utilized as the closure model in ANSYS Fluent. Three turbulence intensities (1%, 5%, and 10%) were examined over angles of attack spanning from 0° to 30°. Significant reduction in lift-to-drag ratio was observed pre-stall with a contrasting enhancement post-stall with increasing turbulence intensities. In addition, onset of stall was delayed. Statistical analysis, employing ANOVA, based on 800 design points from 0.1% to 20% confirmed turbulence intensity as a significant parameter governing lift-to-drag ratio explaining 42.5% of the associated variance. The effect was substantial at lower angles of attack and diminished at higher angles as post-stall conditions dominated. The present work demonstrates a non-linear and regime-dependent influence of turbulence intensity over NACA2414 airfoil performance at a transitional flow regime, directly relevant to small-scale wind turbine operation. Rotor-level analysis using a validated blade element momentum model further indicates a reduction in mechanical power output with increasing turbulence intensity. The findings establish turbulence intensity as a critical design parameter for low-Reynolds number wind turbine airfoils. • Explored turbulence intensity impact on NACA2414 airfoil at a Reynolds number of 10 5 . • Behavior in pre-stall and post-stall regions at higher turbulence intensity are discussed. • Patterns in lift, drag coefficients and boundary layer development are discussed. • Established turbulence intensity as a critical parameter through a comprehensive ANOVA test. • Blade Element Momentum analysis revealed a 59.23% reduction in mechanical power as turbulence intensity increased from 1% to 10%.
Krishnan et al. (Fri,) studied this question.