Wells Turbine Stall Control Using Plasma Actuators

Greenblatt, David; Pfeffermann, Omer; Keisar, David; Göksel, B.

doi:10.2514/1.j060278

Cited by 15 publications

(2 citation statements)

References 28 publications

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“…20 Since the blade cascade effect decreases along with the solidity from the hub to tip with constant chord blades in Wells turbines, the flow separation, and consequently the stall, is prone to occur from the tip to the hub region. To suppress the leading-edge separation, some control methods were directed toward the flow near the LE of Wells turbine blades, such as the dielectric barrier discharge plasma actuators 21 and leading-edge microcylinder. 22 In these studies, stall points of the Wells turbine can be effectively delayed.…”

Section: Introductionmentioning

confidence: 99%

Influence of vortex interactions on the exergy transfer and performance of OWC wells turbine

Geng¹,

Yang²,

Zhang³

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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To provide deep dives about aerodynamic loss mechanisms in Wells turbines for wave energy conversion, a loss audit analysis was performed by numerical experiments in a monoplane Wells turbine with guide vanes. The interactions between the tip-leakage and leading-edge vortices during the stall process were captured by an improved vortex identification method, which revealed the relationship between vortex interactions and stall mechanisms by identifying coherent structures and tracking the vortex core trajectory. Finally, the influence of vortex interactions on exergy transfer was quantified. The results indicate that the lost kinetic energy and mixing losses dominate the loss generation in the Wells turbine stage under stall conditions. Under the beneficial effect of tip leakage flow, leading-edge separation first begins at the equilibrium region between the tip-leakage and leading-edge vortices. As the leading-edge vortices expand toward the blade tip, the intensified leading-edge vortex interacts with the casing suction-side corner vortex and accelerates the dissipation of the tip-leakage vortices. Consequently, the contributions of viscous irreversibilities outweigh those of shaft work, being the dominant factor in the decrease in flow exergy, leading to a decrease in exergy utilization by 38.46% from the pre-stall condition to the stall condition.

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Section: Introductionmentioning

confidence: 99%

Influence of vortex interactions on the exergy transfer and performance of OWC wells turbine

Geng¹,

Yang²,

Zhang³

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Active mechanical methods, such as trailing-edge flaps and variable-droop leading edges, often cause significant changes to the center of gravity and load, while frequently requiring intricate mechanical elements and control systems. In this research, we employ pulse-modulated dielectric barrier discharge (DBD) plasma actuators, ideally suited to rotor application due to their lightweight and high-frequency bandwidth [15][16][17][18][19]. In the past, DBD plasma actuators have been employed to attenuate the tonal noise from cavities [20,21], to reduce slat aerodynamic noise [22], and to control flow noise generated by cylinders [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Noise Reduction on a Model Helicopter Rotor using DBD Plasma Actuators

Polonsky¹,

Stalnov²,

Greenblatt³

2022

Preprint

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Noise reduction was achieved on a model helicopter rotor using pulsed dielectric barrier discharge (DBD) plasma actuators mounted at the blades' leading edges. The rotor was mounted on a bi-axial balance in an anechoic chamber, and the following three-point noise-reduction strategy was adopted: first, the blades' collective (geometric) angle was increased into the post-stall regime to achieve maximum baseline thrust; second, actuation was applied, increasing thrust and decreasing torque; third, the rotational speed was decreased to recover the original baseline thrust. This strategy resulted in an increase in the maximum Figure of Merit and a decrease in broadband and tonal noise components. Broadband and loading noise reduction, up to 3 dB, was due to boundary layer attachment, resulting in smaller and weaker turbulent eddies in the wake and the tip-vortex and, therefore, more minor turbulent surface pressure fluctuations. Noise reduction directivity associated with the blade passing frequency of up to 3 dB was consistent with Lowson's theory. Surprisingly, at most of the observer angles, both the plasma pulsation and ionization frequencies were not visible in the spectra. This directional acoustic signature was assumed to be due to the geometric mounting of the actuator and its effect on the boundary layer.

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