Experimental and Numerical Investigation of Roughness Structure in Wind Turbine Airfoil at Low Reynolds Number

Abstract

This paper experimentally and numerically investigates the effects of suction side surface roughness on the aerodynamic performances of the NACA 0015 turbine blade profile. Three different NACA 0015 turbine blade configurations, which are smooth (K0), single roughness (K1), and double roughness (K2), are considered. The experimental studies were conducted using the HM-170 GUNT open wind tunnel model. The aerodynamic characteristics of these three blade configurations are evaluated in terms of their lift coefficient (CL), drag coefficient (CD), and aerodynamic efficiency (CL/CD). The maximum CL (CL,max) for K0 was obtained at 25°, whereas the CL,max angles for the K1 and K2 roughness blade profiles were reduced to 22.5°, utilizing the rough surfaces on the suction side. The experimental analysis revealed that the K2 profile demonstrated a 21% and 19% enhancement in maximal CL over the K0 and K1 profiles, respectively. The highest CL/CD was observed with K1, except at low attack of angle (αoα), where the smooth blade profile resulted in slightly better performance. Experimental analysis showed peak CL/CD at αoα of 7.5° for K0, and 12.5° for both K1 and K2, with K1's optimal CL/CD being 2.85% and 8.5% higher than K0 and K2, respectively. Numerical analysis indicated that the CL/CD,avg for K1 was observed to be 11% and 8% higher than that of K0 across all αoα.