Investigation of the benefits of unsteady blowing actuation on a 2D wind turbine blade

Abstract

This paper investigates the benefit of unsteady blowing actuation over a two-dimensional (2D) airfoil specially designed for wind turbine applications. The experiments were carried out in Syracuse University's anechoic wind tunnel, both with and without large-scale unsteadiness in the free stream generated by a 2D cylinder upstream of the airfoil. By analyzing both surface pressure through wavelet analysis and Particle Image Velocimetry (PIV) velocity field measurements, we found a drastic change in the flow physics and the aerodynamic loading on the airfoil between steady and unsteady free-stream conditions. When there was no large-scale unsteadiness introduced in the flow, under open-loop flow control conditions with unsteady blowing, the leading-edge separation was delayed and the maximum lift coefficient was increased. For the cases where large-scale unsteadiness was introduced into the flow, the experiments showed that both open-loop and closed-loop control cases were capable of reducing load fluctuations by a measurable amount. However, only the closed-loop control case that utilized dynamic surface pressure information from the airfoil suction side near the leading edge was capable of consistently mitigating the fluctuating load.

Review of Flow-Control Devices for Wind-Turbine Performance Enhancement

“…Applying the blowing mechanism for aerodynamic load control is also feasible. In [265], the application of pulsating jets reduced the root mean-square (RMS) of the fluctuating load of wind turbine blades by up to 12%. Moreover, load alleviation induced by a suction or pulsed-blowing coupled mechanism [266] is attributable to boundarylayer extraction (suction) and energizing (blowing), unsteady shear-layer excitation, thrust generation and streamwise vortices.…”

Dynamic Stall Control on the Wind Turbine Airfoil via a Co-Flow Jet

“…Hence, for a flow control method, it is important to provide the blade with both, good static and dynamic, aerodynamic perofmance. Various flow control methods have been investigated to enhance wind turbine blade performance, including trailing edge flaps [5], microtabs [6,7], vortex generators [8], blowing jets [9,10], circulation control [11], Gurney flaps [11], synthetic jets [12], and plasma actuators [13]. Hanns et al [10] carried out an experimental study to explore constant blowing as a flow control concept for wind turbine blades.…”