Performance optimization and investigation of flow phenomena on tidal turbine blade airfoil considering cavitation and roughness

1998 ◽

Cited By ~ 10

Author(s):

C. R. Hedlund ◽

P. M. Ligrani ◽

H.-K. Moon ◽

B. Glezer

Keyword(s):

Heat Transfer ◽

Turbine Blade ◽

Flow Characteristics ◽

Leading Edge ◽

Internal Cooling ◽

Vortex Pairs ◽

Nusselt Numbers ◽

Swirl Chamber ◽

Flow Phenomena ◽

Energy Balances

Heat transfer and fluid mechanics results are given for a swirl chamber whose geometry models an internal passage used to cool the leading edge of a turbine blade. The Reynolds numbers investigated, based on inlet duct characteristics, include values which are the same as in the application (18000–19400). The ratio of absolute air temperature between the inlet and wall of the swirl chamber ranges from 0.62 to 0.86 for the heat transfer measurements. Spatial variations of surface Nusselt numbers along swirl chamber surfaces are measured using infrared thermography in conjunction with thermocouples, energy balances, digital image processing, and in situ calibration procedures. The structure and streamwise development of arrays of Görtler vortex pairs, which develop along concave surfaces, are apparent from flow visualizations. Overall swirl chamber structure is also described from time-averaged surveys of the circumferential component of velocity, total pressure, static pressure, and the circumferential component of vorticity. Important variations of surface Nusselt numbers and time-averaged flow characteristics are present due to arrays of Görtler vortex pairs, especially near each of the two inlets, where Nusselt numbers are highest. Nusselt numbers then decrease and become more spatially uniform along the interior surface of the chamber as the flows advect away from each inlet.

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Experimental analysis of the shear flow effect on tidal turbine blade root force from three-dimensional mean flow reconstruction

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2020.0001 ◽

2020 ◽

Vol 378 (2178) ◽

pp. 20200001 ◽

Cited By ~ 1

Author(s):

B. Gaurier ◽

Ph. Druault ◽

M. Ikhennicheu ◽

G. Germain

Keyword(s):

Turbine Blade ◽

Dimensional Space ◽

Three Dimensional ◽

Tidal Energy ◽

Velocity Shear ◽

Reconstruction Method ◽

Mean Flow ◽

Blade Root ◽

Image Velocimetry ◽

Tidal Turbine

In the main tidal energy sites like Alderney Race, turbulence intensity is high and velocity fluctuations may have a significant impact on marine turbines. To understand such phenomena better, a three-bladed turbine model is positioned in the wake of a generic wall-mounted obstacle, representative of in situ bathymetric variation. From two-dimensional Particle Image Velocimetry planes, the time-averaged velocity in the wake of the obstacle is reconstructed in the three-dimensional space. The reconstruction method is based on Proper Orthogonal Decomposition and enables access to a representation of the mean flow field and the associated shear. Then, the effect of the velocity gradient is observed on the turbine blade root force, for four turbine locations in the wake of the obstacle. The blade root force average decreases whereas its standard deviation increases when the distance to the obstacle increases. The angular distribution of this phase-averaged force is shown to be non-homogeneous, with variation of about 20% of its time-average during a turbine rotation cycle. Such force variations due to velocity shear will have significant consequences in terms of blade fatigue. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

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Accelerated life testing study of a novel tidal turbine blade attachment

International Journal of Fatigue ◽

10.1016/j.ijfatigue.2018.05.029 ◽

2018 ◽

Vol 114 ◽

pp. 226-237 ◽

Cited By ~ 2

Author(s):

Oscar de la Torre ◽

Daithi Moore ◽

Declan Gavigan ◽

Jamie Goggins

Keyword(s):

Turbine Blade ◽

Accelerated Life Testing ◽

Life Testing ◽

Accelerated Life ◽

Tidal Turbine

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Differential evolution algorithm for performance optimization of the micro plasma actuator as a microelectromechanical system

Scientific Reports ◽

10.1038/s41598-020-75419-5 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Javad Omidi ◽

Karim Mazaheri

Keyword(s):

Differential Evolution ◽

Wind Turbine ◽

Turbine Blade ◽

Performance Optimization ◽

Stokes Equations ◽

Differential Evolution Algorithm ◽

Aerodynamic Performance ◽

Wind Turbine Blade ◽

Electrostatic Model ◽

Dielectric Thickness

Abstract Dielectric Discharge Barrier (DBD) plasma actuators are considered as one of the best active electro-hydrodynamic control devices, and are considered by many contemporary researchers. Here a simple electrostatic model, which is improved by authors, and uses the Maxwell’s and the Navier–Stokes equations, is proposed for massive optimization computations. This model is used to find the optimum solution for application of a dielectric discharge barrier on a curved surface of a DU25 wind turbine blade airfoil, in a range of 5–18 kV applied voltages, and 0.5 to 13 kHz frequency range. Design variables are selected as the dielectric thickness and material, and thickness and length of the electrodes, and the applied voltage and frequency. The aerodynamic performance, i.e. the lift to drag ratio of the wind turbine blade section is considered as the cost function. A differential evolution optimization algorithm is applied and we have simultaneously found the optimized value of both geometrical and operational parameters. Finally the optimized value at each voltage and frequency are sought, and the optimum aerodynamic performance is derived. The physical effect of each design variable on the aerodynamic performance is discussed. A design relation is proposed to recommend an optimum design for wind turbine applications.

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Heat Transfer and Flow Phenomena in a Swirl Chamber Simulating Turbine Blade Internal Cooling

Journal of Turbomachinery ◽

10.1115/1.2836734 ◽

1999 ◽

Vol 121 (4) ◽

pp. 804-813 ◽

Cited By ~ 30

Author(s):

C. R. Hedlung ◽

P. M. Ligrani ◽

H.-K. Moon ◽

B. Glezer

Keyword(s):

Heat Transfer ◽

Turbine Blade ◽

Flow Characteristics ◽

Leading Edge ◽

Internal Cooling ◽

Vortex Pairs ◽

Nusselt Numbers ◽

Swirl Chamber ◽

Flow Phenomena ◽

Energy Balances

Heat transfer and fluid mechanics results are given for a swirl chamber whose geometry models an internal passage used to cool the leading edge of a turbine blade. The Reynolds numbers investigated, based on inlet duct characteristics, include values that are the same as in the application (18,000–19,400). The ratio of absolute air temperature between the inlet and wall of the swirl chamber ranges from 0.62 to 0.86 for the heat transfer measurements. Spatial variations of surface Nusselt numbers along swirl chamber surfaces are measured using infrared thermography in conjunction with thermocouples, energy balances, digital image processing, and in situ calibration procedures. The structure and streamwise development of arrays of Go¨rtler vortex pairs, which develop along concave surfaces, are apparent from flow visualizations. Overall swirl chamber structure is also described from time-averaged surveys of the circumferential component of velocity, total pressure, static pressure, and the circumferential component of vorticity. Important variations of surface Nusselt numbers and time-averaged flow characteristics are present due to arrays of Go¨rtler vortex pairs, especially near each of the two inlets, where Nusselt numbers are highest. Nusselt numbers then decrease and become more spatially uniform along the interior surface of the chamber as the flows advect away from each inlet.

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Parameterization of a Multi-Directional Tidal Turbine Performance Using Computational Fluid Dynamics

Volume 9: Ocean Renewable Energy ◽

10.1115/omae2015-41035 ◽

2015 ◽

Author(s):

Richard B. Medvitz ◽

Michael L. Jonson ◽

James J. Dreyer ◽

Jarlath McEntee

Keyword(s):

Turbine Blade ◽

Three Dimensional ◽

Operating Conditions ◽

Moving Mesh ◽

Cfd Analysis ◽

Two Dimensional ◽

Peak Efficiency ◽

Trailing Edge ◽

Blade Shape ◽

Tidal Turbine

High resolution RANS CFD analysis is performed to support the design and development of the Ocean Renewable Power Company (ORPC) TidGen™ multi-directional tidal turbine. Two-dimensional and three-dimensional unsteady, moving-mesh CFD is utilized to parameterize the device performance and to provide guidance for device efficiency improvements. The unsteady CFD analysis was performed using a well validated, naval hydrodynamic CFD solver and implementing dynamic overset meshes to perform the relative motion between geometric components. This dynamic capability along with the turbulence model for the expected massively separated flows was validated against published data of a high angle of attack pitching airfoil. Two-dimensional analyses were performed to assess both blade shape and operating conditions. The blade shape performance was parameterized on both blade camber and trailing edge thickness. The blades shapes were found to produce nearly the same power generation at the peak efficiency tip speed ratio (TSR), however off-design conditions were found to exhibit a strong dependency on blade shape. Turbine blades with the camber pointing outward radially were found to perform best over the widest range of TSR’s. In addition, a thickened blade trailing edge was found to be superior at the highest TSR’s with little performance degradation at low TSR’s. Three-dimensional moving mesh analyses were performed on the rotating portion of the full TidGen™ geometry and on a turbine blade stack-up. Partitioning the 3D blades axially showed that no sections reached the idealized 2D performance. The 3D efficiency dropped by approximately 12 percentage points at the peak efficiency TSR. A blade stack-up analysis was performed on the complex 3D/barreled/twisted turbine blade. The analysis first assessed the infinite length blade performance, next end effects were introduced by extruding the 2D foil to the nominal 5.6m length, next barreling was added to the straight foils, and finally twist was added to the foils to reproduce the TidGen™ geometry. The study showed that making the blades a finite length had a large negative impact on the performance, whereas barreling and twisting the foils had only minor impacts. Based on the 3D simulations the largest factor impacting performance in the 3D turbine was a reduction in mass flow through the turbine due to the streamlines being forces outward in the horizontal plane due to the turbine flow resistance. Strategies to mitigate these 3D losses were investigated, including adding flow deflectors on the turbine support structure and stacking multiple turbines in-line.

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