Experimental investigation of the effect of active flow control on the wake of a wind turbine blade

Abstract

An extensive experimental investigation was conducted to study the effects of Dielectric Barrier Discharge (DBD), on the flow field of an airfoil at low Reynolds number. The DBD was mounted near the leading edge of a section of a wind turbine blade. It is believed that DBD can postpone the separation point on the airfoil by injecting momentum to the flow. The effects of steady actuations on the velocity profiles in the wake region have been investigated. The tests were performed at α = 4 to 36 degrees i.e. from low to deep stall angles of attack regions. Both surface pressure distribution and wake profile show remarkable improvement at high angles of attack, beyond the static stall angle of the airfoil when the plasma actuation was implemented. The drag calculated from the wake momentum deficit has further shown the favorable role of the plasma actuators to control the flow over the airfoil at incidences beyond the static stall angle of attack of this airfoil. The results demonstrated that DBD has been able to postpone the stall onset significantly. It has been observed that the best performance for the plasma actuation for this airfoil is in the deep stall angles of attack range. However, below and near the static stall angles of attack, plasma augmentation was pointed out to have a negligible improvement in the aerodynamic behavior.

Genetic algorithm optimization of a horizontal axis wind turbine blade section performance equipped with a single dielectric barrier discharge plasma actuator utilizing a direct regression model

“…It is believed that PA has no remarkable impact on the pre-stall region. 11,12,36–38 Therefore, in present research, post-stall and deep stall regions were the major concern of PA influence investigations and the pre-stall region (0°–10° AOAs) was not investigated.

Figure 10. Lift-to-drag ratio for PA located at different places over the airfoil suction side at Reynolds number of a) 1.425 × 10 5 , b) 2.85 × 10 5 , and c) 4.274 × 10 5 .

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“…It is believed that PA has no remarkable impact on the pre-stall region. 11,12,[36][37][38] Therefore, in present research, post-stall and deep stall regions were the major concern of PA influence investigations and the pre-stall region (0°-10°A OAs) was not investigated.…”

“…2 To address these issues, wide range of flow control technologies have been adjusted for HAWTs, for instance, passive flow control via triangular, 3 rectangular, 4 and rod shape vortex generators, 5 morphed trailing edge (TE) flap, 6 leading edge (LE) slat, 7 down-stream facing winglets 8 as well as active flow control via microtabs and microjets 9 and dielectric barrier discharge plasma actuators (DBD-PAs). [10][11][12] In addition to extensive researches performed on the utilization of the various flow control devices over HAWTs and their consequent beneficiary effects, evolutionary algorithms have been substantially exploited for shape, aerodynamic, structural, and energy production optimization of wind turbine blades. Mohamed and Shaaban 13 investigated the two different blade geometries of Wells turbine optimum pitch angle to improve the energy share of the turbine.…”

“…2 To address these issues, wide range of flow control technologies have been adjusted for HAWTs, for instance, passive flow control via triangular, 3 rectangular, 4 and rod shape vortex generators, 5 morphed trailing edge (TE) flap, 6 leading edge (LE) slat, 7 down-stream facing winglets 8 as well as active flow control via microtabs and microjets 9 and dielectric barrier discharge plasma actuators (DBD-PAs). 10–12…”