The influence of ZigZag stripe on wind turbine aerodynamic loads in wind tunnel measurement and CFD predictions

摘要

ZigZag stripe is an effective tool to artificially trigger flow transition at fixed position when measuring aerodynamic characteristics of airfoils or wind turbine rotor performance in wind tunnel test. In this paper, the influence of ZigZag stripe on wind turbine aerodynamic loads is investigated by analysis of several wind tunnel experimental results, namely the MEXICO experiment and the non-rotating MEXICO experiment. The local chordwise pressure distribution, integral lift and drag force, at two radial locations r=R = 0:35 and 0:92, are compared for two blade configurations: clean blade and rough blade with ZigZag stripe. The results imply that the ZigZag stripe, not only acts as a tripping device to trigger boundary layer flow turbulent, but also alters the airfoil boundary layer displacement thickness as well as the airfoil camber. Compared with fully turbulent 3D CFD simulations, it is observed that CFD overpredicts aerodynamic loads, which could be attributed to the alteration induced by the ZigZag stripe. The contribution of this work aims to find the possible reason results in signifficant overprediction of blade tip loads by all CFD simulations found in the literature, comparing to the measured loads in the rotating MEXICO experiment.