Truncated vortex generators for part-depth wind-tunnel simulations of the atmospheric boundary layer flow

Kozmar, Hrvoje

doi:10.1016/j.jweia.2010.11.001

Cited by 39 publications

(12 citation statements)

References 21 publications

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“…The flow and the turbulence were analyzed with respect to the mean velocity, turbulence intensity, Reynolds stress, integral length scales of turbulence, and power spectral density of velocity fluctuations, as this set of ABL parameters allows for a comprehensive analysis of ABL characteristics, e.g. [36], [37], [38], [39], [40]. The ABL velocity profiles without the hill model were normalized using the reference velocity u in the lower ABL (above the displacement height), as this way of normalization is common when studying ABL wind tunnel simulations.…”

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Wind Characteristics in the Wake of a Non-Rotating Wind Turbine close to a Hill

Kozmar

Allori

Bartoli

et al. 2019

TFAMENA

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Hilly terrain may considerably influence energy yield and structural loading of wind turbines. Wind energy developers are therefore required to accurately predict wind characteristics at the wind farm site already in the designing phase. It is necessary to determine how particular hill shape and size affect wind characteristics at the location of wind turbines operating in the wake of a hill. In order to address this complex issue, small-scale laboratory experiments were carried out in a boundary layer wind tunnel (BLWT). The focus was on characteristics of the flow at the same position downstream of the hill and the wind turbine models studied on various sizes and shapes of the hill model. Three hill models (a small and a large hill with laterally uniform heights and a hill with a bay) were exposed to the thermally neutrally stratified atmospheric boundary layer (ABL) simulation. In each experiment, there was only one hill model in the BLWT test section. The configuration without the hill, i.e. the flat terrain model, was tested as a reference case. Downstream of the hill model, there was a single (alone-standing) wind turbine model. Flow characteristics were studied downstream (behind) the wind turbine model. The wind turbine model was in the parking position in order to study wind characteristics in the situation with a strong wind when there is no rotation of rotor blades. The experimental results indicate a velocity decrease and stronger turbulence in the wind turbine wake in the presence of a hill, which trend is more pronounced in the case of larger hills. Strong velocity gradients are observed around the hub height in the large hill configuration, while this velocity deficit is the smallest in the hill with a bay configuration due to flow channeling. The velocity power spectra reveal the characteristic peak due to the vortex shedding from the hill ridge. The obtained results provide a new insight into the turbulent wake characteristics of a single wind turbine placed downstream of a hill with a potential to serve as a validation tool for computational studies.

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Wind Characteristics in the Wake of a Non-Rotating Wind Turbine close to a Hill

Kozmar

Allori

Bartoli

et al. 2019

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“…In the 1:395 simulation, five full-size vortex generators were used. In the 1:236 simulation, three full-size vortex generators, and in the 1:208 simulation three redesigned (truncated) vortex generators were employed [22]. Design details of three types of vortex generators applied in this study are shown in Fig.…”

Section: Wind-tunnel Experimentsmentioning

confidence: 99%

Physical modeling of complex airflows developing above rural terrains

Kozmar

2011

Environ Fluid Mech

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The rural atmospheric boundary layer (ABL) flow was reproduced in a wind tunnel at three different simulation length scales to investigate possible effects of the simulation length scale on flow characteristics. Performance of truncated vortex generators developed for part-depth ABL wind-tunnel simulations was tested in rural terrain exposure against the full-size Counihan vortex generators. A procedure to design the ABL developing above rural type terrain has been described. The 1:395 and 1:236 simulations were created as full-depth simulations, i.e., wind characteristics throughout an entire ABL were reproduced in the wind tunnel. The 1:208 simulation was a part-depth simulation, i.e., only a lower 70% of the ABL was experimentally modelled. The projected scaled-up ABL thicknesses are 395, 354, and 416 m full-scale in the 1:395, 1:236, and 1:208 simulations, respectively. Experimental results show similar trends in all three configurations not depending on the simulation length scale factor. This clearly indicates a possibility to physically, in the wind tunnel, reproduce the same rural atmospheric airflows at different simulation length scales.

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“…On the other hand, in the work by Seshagiri et al (2009), the effectiveness of using dynamic oscillating VGs has been proved for low Reynolds numbers to be not relevant to justify the augmented system complexity. In the work by Kozmar (2011), the ability of ad hoc–designed “Counihan” VGs for part-depth atmospheric boundary layer (ABL) wind tunnel simulations is reported, based on a good agreement with the full-scale data for rural, urban, and suburban ABL cases.…”

Section: Introductionmentioning

confidence: 99%

An extension of a strong viscous–inviscid coupling method for modeling the effects of vortex generators

et al. 2018

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The aim of this work is to provide insights into the advantages and the limitations of the extension of a strong viscous-inviscid interactive code for modeling the effects of vortex generators, with focus on the calibration and validation for wind turbine airfoils. The proposed methodology relies on the approach proposed by other authors in the past and introduces an alternative formulation for the lag dissipation within the integral boundary-layer equations whose effects on the numerical prediction are evaluated. Besides the verification of the aeronautical test cases, particular attention is devoted to the validation of the results for several airfoils commonly used in wind turbine design. A blind test for airfoils from an industrial test case is conducted as well. Results show that the maximum lift coefficient can be well predicted by the present implementation, whereas the angle of maximum lift is a little higher than in wind tunnel measurements. Apart from that, the drag coefficients of airfoils with vortex generators cannot be predicted by the current implementation, but it is expected that the maximum lift and the stall angle of attack are more important in the design phase, since they determine power, loads, and noise.

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Truncated vortex generators for part-depth wind-tunnel simulations of the atmospheric boundary layer flow

Cited by 39 publications

References 21 publications

Wind Characteristics in the Wake of a Non-Rotating Wind Turbine close to a Hill

Wind Characteristics in the Wake of a Non-Rotating Wind Turbine close to a Hill

Physical modeling of complex airflows developing above rural terrains

An extension of a strong viscous–inviscid coupling method for modeling the effects of vortex generators

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