Three-dimensional flow visualization in the wake of a miniature axial-flow hydrokinetic turbine

Chamorro, Leonardo P.; Troolin, Dan; Lee, Seung-Jae; Arndt, Roger E. A.; Sotiropoulos, Fotis

doi:10.1007/s00348-013-1459-9

Cited by 42 publications

(32 citation statements)

References 19 publications

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“…Their results showed a breaking of the helical symmetry and merging of the vortices in the wake. Using 3D visualizations in the wake of a miniature axial-flow turbine, Chamorro et al (2012a) observed the propagation, stability and interaction between consecutive tip vortices. They noted that instability can be triggered by vortex-to-vortex interactions.…”

Section: Introductionmentioning

confidence: 99%

Detection of tip-vortex signatures behind a 2.5 MW wind turbine

Toloui

Chamorro

Hong

2015

Journal of Wind Engineering and Industrial Aerodynamics

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a b s t r a c tThe near-field signature of the vortical structures shed from the blade tips behind a 2.5 MW horizontal axis wind turbine in a stably-stratified atmospheric boundary layer (ABL) was quantified for the first time. This study utilizes wind velocity measurements from sonic anemometers installed on a meteorological tower, which offers continuous characterization of wind conditions in the field, at elevations coinciding with the bottom, hub and top tip heights of the turbine. Using the stringent criteria on wind speed, direction and steadiness, we are able to subsample the dataset in which the sonic anemometers are positioned near the edge of the turbine wake. The spectral analysis of this dataset shows a distinct peak at the turbine rotational frequency (f T ) for hub and top tip height measurements. Based on recent literature, we infer that this peak is the signature of tip-vortices, and the shift of this signature from blade-passing frequency (3f T ) to f T is likely to be caused by vortex grouping phenomena. Slight changes of mean wind direction in other data samples result in the absence of the spectral peak, suggesting the very local extent of tip vortices.

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Section: Introductionmentioning

confidence: 99%

Detection of tip-vortex signatures behind a 2.5 MW wind turbine

Toloui

Chamorro

Hong

2015

Journal of Wind Engineering and Industrial Aerodynamics

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“…The well-known λ 2 -criterion is used to visualize the three-dimensional vortical structures in the very near wake region. 20 Similar setup and visualization techniques are described in Chamorro et al 21 Although specific details of such experiment are beyond the scope of the paper, the main message is highlighted in Figure 4 as a motivation for the present measurements. Subplot 4(a) depicts the von-Karman vortices shed by the cylinder only; similarly, subplot 4(b) shows the tip vortices shed from the turbine alone, while subplot 4(c) illustrates the very near wake of the turbine with the cylinder placed upstream of the rotor.…”

Section: B Turbine Wakementioning

confidence: 94%

Effects of energetic coherent motions on the power and wake of an axial-flow turbine

et al. 2015

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A laboratory experiment examined the effects of energetic coherent motions on the structure of the wake and power fluctuations generated by a model axial-flow hydrokinetic turbine. The model turbine was placed in an open-channel flow and operated under subcritical conditions. The incoming flow was locally perturbed with vertically oriented cylinders of various diameters. An array of three acoustic Doppler velocimeters aligned in the cross-stream direction and a torque transducer were used to collect high-resolution and synchronous measurements of the three-velocity components of the incoming and wake flow as well as the turbine power. A strong scale-to-scale interaction between the large-scale and broadband turbulence shed by the cylinders and the turbine power revealed how the turbulence structure modulates the turbine behavior. In particular, the response of the turbine to the distinctive von Kármán-type vortices shed from the cylinders highlighted this phenomenon. The mean and fluctuating characteristics of the turbine wake are shown to be very sensitive to the energetic motions present in the flow. Tip vortices were substantially dampened and the near-field mean wake recovery accelerated in the presence of energetic motions in the flow. Strong coherent motions are shown to be more effective than turbulence levels for triggering the break-up of the spiral structure of the tip-vortices. C 2015 AIP Publishing LLC. [http://dx.

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“…A study carried out on an axial turbine by Chamorro et al revealed that the distance equals to four times the diameter is considered as the transition zone. Harrison et al validated the same work through computational fluid dynamics (CFD), which differs in the length of transition zone by two times the diameter of the turbine.…”

Section: Review On Hydrokinetic Potential Assessmentmentioning

confidence: 99%

Development of hydrokinetic energy technology: A review

Sood

Singal

2019

Int J Energy Res

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Summary The drastic change in climatic conditions has led to shift towards the review of sustainable strategies in the renewable energy sector. Hydrokinetic technology has various benefits over the conventional methods, which can be helpful in achieving the desired sustainable development. In the present study, an outline for the conversion of hydrokinetic energy along with its challenges has been discussed. The study comprises of three steps involving collection of properties required for site characterization followed by selection of the suitable hydrokinetic device as per the site characteristics and the determination of impact on the flow condition due to device installation. The characteristics of the site govern the selection of the device, its mooring arrangements, and augmentation. The arrangement of devices as a single unit or in an array will have an impact on the flow conditions. The altered flow condition will in turn affect and change the characteristics of the site. This three‐step process is interlinked and will have a cumulative impact on the environment. The influence of environmental impact and cost of energy, which are the two major factors for the success of this technology, are also discussed. Further, various challenges faced by hydrokinetic technology in its development are explored. It is concluded that only the optimization of a hydrokinetic device for its efficiency improvement will not be fruitful until its impact on flow condition is considered for optimization.

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Three-dimensional flow visualization in the wake of a miniature axial-flow hydrokinetic turbine

Cited by 42 publications

References 19 publications

Detection of tip-vortex signatures behind a 2.5 MW wind turbine

Detection of tip-vortex signatures behind a 2.5 MW wind turbine

Effects of energetic coherent motions on the power and wake of an axial-flow turbine

Development of hydrokinetic energy technology: A review

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