Reynolds effects on wall pressure fluctuations at stall inception of a wind turbine blade section

Abstract

Understanding the flow physics over airfoils near stall is of major importance for improvement of dynamic stall models. However, static stall is a first important step that remains challenging. The present study focuses on the influence of Reynolds number on the stall inception of an airfoil, one of the important parameter impacting the stall behavior. The blade, extracted from scans of an operated 2MW turbine, is investigated experimentally at full scale using two chordwise lines of unsteady wall pressure sensors with Reynolds numbers ranging from 5 × 105 to 4.2 × 106. Results reveal an important dependence of the pressure fluctuations with the Reynolds number: their relative level compared with the intrados value is progressively increased with the Reynolds number in the intermittent separation region which corresponds to the peak of pressure standard deviation.