Effect of oncoming flow turbulence on the kinetic energy transport in the flow around a model wind turbine

2018 ◽  
Author(s):  
Wei Tian ◽  
Hui Hu
Keyword(s):  
Kinetic Energy ◽  
Wind Turbine ◽  
Energy Transport ◽  
Oncoming Flow ◽  
Flow Turbulence

Tip-vortex instability and turbulent mixing in wind-turbine wakes

2015 ◽  
Vol 781 ◽  
pp. 467-493 ◽  
Author(s):  
L. E. M. Lignarolo ◽  
D. Ragni ◽  
F. Scarano ◽  
C. J. Simão Ferreira ◽  
G. J. W. van Bussel
Keyword(s):  
Kinetic Energy ◽  
Wind Turbine ◽  
Shear Layer ◽  
Turbulent Mixing ◽  
Energy Transport ◽  
Stereoscopic Particle Image Velocimetry ◽  
Tip Vortex ◽  
Sudden Increase ◽  
Horizontal Axis Wind Turbine

Kinetic-energy transport and turbulence production within the shear layer of a horizontal-axis wind-turbine wake are investigated with respect to their influence on the tip-vortex pairwise instability, the so-called leapfrogging instability. The study quantifies the effect of near-wake instability and tip-vortex breakdown on the process of mean-flow kinetic-energy transport within the far wake of the wind turbine, in turn affecting the wake re-energising process. Experiments are conducted in an open-jet wind tunnel with a wind-turbine model of 60 cm diameter at a diameter-based Reynolds number range $\mathit{Re}_{D}=150\,000{-}230\,000$. The velocity fields in meridian planes encompassing a large portion of the wake past the rotor are measured both in the unconditioned and the phase-locked mode by means of stereoscopic particle image velocimetry. The detailed topology and development of the tip-vortex interactions are discussed prior to a statistical analysis based on the triple decomposition of the turbulent flow fields. The study emphasises the role of the pairing instability as a precursor to the onset of three-dimensional vortex distortion and breakdown, leading to increased turbulent mixing and kinetic-energy transport across the shear layer. Quadrant analysis further elucidates the role of sweep and ejection events within the two identified mixing regimes. Prior to the onset of the instability, vortices shed from the blade appear to inhibit turbulent mixing of the expanding wake. The second region is dominated by the leapfrogging instability, with a sudden increase of the net entrainment of kinetic energy. Downstream of the latter, random turbulent motion characterises the flow, with a significant increase of turbulent kinetic-energy production. In this scenario, the leapfrogging mechanism is recognised as the triggering event that accelerates the onset of efficient turbulent mixing followed by the beginning of the wake re-energising process.

Utilisation of kinetic energy from wind turbine for grid connections: a review paper

2018 ◽  
Vol 12 (6) ◽  
pp. 615-624 ◽  
Author(s):  
Dongxiao Wang ◽  
Xiaodan Gao ◽  
Ke Meng ◽  
Jing Qiu ◽  
Loi Lei Lai ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Wind Turbine ◽  
Review Paper

scholarly journals Kinetic energy entrainment in wind turbine and actuator disc wakes: an experimental analysis

2014 ◽  
Vol 524 ◽  
pp. 012163 ◽  
Author(s):  
L E M Lignarolo ◽  
D Ragni ◽  
C J Simão Ferreira ◽  
G J W van Bussel
Keyword(s):  
Kinetic Energy ◽  
Wind Turbine ◽  
Experimental Analysis ◽  
Actuator Disc

scholarly journals Prediction and measurement of the aerodynamic performance of a wind turbine

2018 ◽  
Vol 240 ◽  
pp. 04001
Author(s):  
Ali Cemal Benim ◽  
Michael Diederich ◽  
Fethi Gül
Keyword(s):  
Wind Turbine ◽  
Transport Model ◽  
Three Dimensional ◽  
Detached Eddy Simulation ◽  
Simulation Framework ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Shear Stress Transport Model ◽  
Flow Turbulence ◽  
Good Agreement

Aerodynamic behavior of a small wind turbine is analyzed, both experimentally and numerically. Mainly, an unsteady three-dimensional formulation is adopted, where the flow turbulence is modelled by an Improved Delayed Detached Eddy Simulation framework, using the four-equation transitional Shear Stress Transport model, as the turbulence model. A quite good agreement between the measurements and calculations is observed.

scholarly journals Energy-consistent entrainment relations for jets and plumes

2015 ◽  
Vol 782 ◽  
pp. 333-355 ◽  
Author(s):  
Maarten van Reeuwijk ◽  
John Craske
Keyword(s):  
Kinetic Energy ◽  
Richardson Number ◽  
Turbulence Kinetic Energy ◽  
Mean Flow ◽  
Unified Framework ◽  
First Order ◽  
Entrainment Coefficient ◽  
The Mean ◽  
Flow Turbulence ◽  
Pure Plume

We discuss energetic restrictions on the entrainment coefficient${\it\alpha}$for axisymmetric jets and plumes. The resulting entrainment relation includes contributions from the mean flow, turbulence and pressure, fundamentally linking${\it\alpha}$to the production of turbulence kinetic energy, the plume Richardson number$\mathit{Ri}$and the profile coefficients associated with the shape of the buoyancy and velocity profiles. This entrainment relation generalises the work by Kaminskiet al. (J. Fluid Mech., vol. 526, 2005, pp. 361–376) and Fox (J. Geophys. Res., vol. 75, 1970, pp. 6818–6835). The energetic viewpoint provides a unified framework with which to analyse the classical entrainment models implied by the plume theories of Mortonet al.(Proc. R. Soc. Lond.A, vol. 234, 1955, pp. 1–23) and Priestley & Ball (Q. J. R. Meteorol. Soc., vol. 81, 1954, pp. 144–157). Data for pure jets and plumes in unstratified environments indicate that to first order the physics is captured by the Priestley and Ball entrainment model, implying that (1) the profile coefficient associated with the production of turbulence kinetic energy has approximately the same value for pure plumes and jets, (2) the value of${\it\alpha}$for a pure plume is roughly a factor of$5/3$larger than for a jet and (3) the enhanced entrainment coefficient in plumes is primarily associated with the behaviour of the mean flow and not with buoyancy-enhanced turbulence. Theoretical suggestions are made on how entrainment can be systematically studied by creating constant-$\mathit{Ri}$flows in a numerical simulation or laboratory experiment.

Experimental Study of the Type VI Stilling Basin Performance

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Seyed Sobhan Aleyasin ◽  
Nima Fathi ◽  
Peter Vorobieff
Keyword(s):  
Experimental Study ◽  
Kinetic Energy ◽  
River Flow ◽  
Doppler Velocimetry ◽  
Huge Amount ◽  
Stilling Basin ◽  
Stilling Basins ◽  
Turbulence Data ◽  
Flow Turbulence ◽  
Acoustic Doppler Velocimetry

Understanding the estuarine turbulent flow from dams, channels, and pipes, as well as the river flow are very important due to the potential to cause damage to the bed of the river or channel and cause scouring of structures such as the saddles of bridges, because of the huge amount of the kinetic energy carried by the flow. One of the most efficient yet simple ways to dissipate this energy is to install a stilling basin at the discharge point to calm the flow. Turbulence data were recorded using acoustic Doppler velocimetry (ADV) for type VI2 of stilling basins for pipe outlets. During the study, various splitters and a cellular baffle were placed in the stilling basin, and the baffle locations were changed to assess the effect on the energy dissipation. Velocity at several locations in the basin was measured for different Froude numbers to investigate the effect of flow rate. Based on the findings of the experiments, several suggestions regarding the efficiency and geometry of stilling basins were made.

Statistical analysis of kinetic energy entrainment in a model wind turbine array boundary layer

2012 ◽  
Vol 4 (6) ◽  
pp. 063105 ◽  
Author(s):  
Nicholas Hamilton ◽  
Hyung Suk Kang ◽  
Charles Meneveau ◽  
Raúl Bayoán Cal
Keyword(s):  
Boundary Layer ◽  
Statistical Analysis ◽  
Kinetic Energy ◽  
Wind Turbine

Turbulent kinetic energy transport in a corner formed by a solid wall and a free surface

2000 ◽  
Vol 410 ◽  
pp. 343-366 ◽  
Author(s):  
T. Y. HSU ◽  
L. M. GREGA ◽  
R. I. LEIGHTON ◽  
T. WEI
Keyword(s):  
Free Surface ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Energy Transport ◽  
Solid Wall
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