Methods of producing velocity profiles in wind tunnels

Lawson, T.V.

doi:10.1016/0004-6981(68)90020-6

Cited by 11 publications

(10 citation statements)

References 10 publications

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“…Simulation techniques and evaluation of similarity between field observations and simulated ABL wind flows have been two main focuses of previous studies. For an example, Lawson (1968) has listed four different techniques including gauzes and honeycombs, rods, flat plates, and obstructions that can be employed to model a turbulent boundary layer in a BLWT. The invention of 'elliptical wedges' by Counihan (1969) has become a successful method for replicating ABL wind flows in a BLWT that has a shorter development section.…”

Section: Introductionmentioning

confidence: 99%

Simulation of twisted wind flows in a boundary layer wind tunnel for pedestrian-level wind tunnel tests

Tse

Weerasuriya

Kwok

2016

Journal of Wind Engineering and Industrial Aerodynamics

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Section: Introductionmentioning

confidence: 99%

Simulation of twisted wind flows in a boundary layer wind tunnel for pedestrian-level wind tunnel tests

Tse

Weerasuriya

Kwok

2016

Journal of Wind Engineering and Industrial Aerodynamics

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“…Furthermore, the minor bump of the mean velocity in the region 0.25 ≤ z/D ≤ 0.5 indicates a not completely developed boundary layer compared to the reference profile (1/7 power law, black dashed line). This effect was often observed in comparable experimental setups, where a sudden change of the flow is enforced by turbulence generators (Lawson, 1968;Counihan, 1969Counihan, , 1975Ligrani et al, 1979;Roberts and Walker, 2003;Sargison et al, 2004). Nevertheless, the overall profiles are similar for each Reynolds number (see Fig.…”

Section: Wind Tunnel and Turbulent Boundary Layermentioning

confidence: 60%

Experimental studies on the instantaneous fluid–structure interaction of an air-inflated flexible membrane in turbulent flow

Wood

Breuer

Nayer

2018

Journal of Fluids and Structures

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“…Mean flows with approximately uniform shears and different shear rates were successfully generated in a water channel. The most obvious drawback of any method using gauze and wires is, as commented by Lawson (1968), that the turbulence characteristics cannot be varied once the wire is chosen, and it is therefore impossible to generate mean velocity and turbulence profiles independently.…”

Section: Shear Generating Methodsmentioning

confidence: 99%

“…Other efforts have also been made to develop different types of devices to produce shear flows in wind tunnel experiments. Some of the most popular methods are briefly reviewed here, and reviews of the earlier methods can be found in Lawson (1968) and Laws and Livesey (1978). Here and for the rest of the discussion, x, y, z represent the streamwise, vertical and transverse direction, respectively.…”

Section: Introductionmentioning

confidence: 99%

Weakly sheared turbulent flows generated by multiscale inhomogeneous grids

et al. 2018

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A group of three multiscale inhomogeneous grids have been tested to generate different types of turbulent shear flows with different mean shear rate and turbulence intensity profiles. Cross hot-wire measurements were taken in a wind tunnel with Reynolds number $Re_{D}$ of 6000–20 000, based on the width of the vertical bars of the grid and the incoming flow velocity. The effect of local drag coefficient $C_{D}$ on the mean velocity profile is discussed first, and then by modifying the vertical bars to obtain a uniform aspect ratio the mean velocity profile is shown to be predictable using the local blockage ratio profile. It is also shown that, at a streamwise location $x=x_{m}$, the turbulence intensity profile along the vertical direction $u^{\prime }(y)$ scales with the wake interaction length $x_{\ast ,n}^{peak}=0.21g_{n}^{2}/(\unicode[STIX]{x1D6FC}C_{D}w_{n})$ ($\unicode[STIX]{x1D6FC}$ is a constant characterizing the incoming flow condition, and $g_{n}$, $w_{n}$ are the gap and width of the vertical bars, respectively, at layer $n$) such that $(u^{\prime }/U_{n})^{2}\unicode[STIX]{x1D6FD}^{2}(C_{D}w_{n}/x_{\ast ,n}^{peak})^{-1}\sim (x_{m}/x_{\ast ,n}^{peak})^{b}$, where $\unicode[STIX]{x1D6FD}$ is a constant determined by the free-stream turbulence level, $U_{n}$ is the local mean velocity and $b$ is a dimensionless power law constant. A general framework of grid design method based on these scalings is proposed and discussed. From the evolution of the shear stress coefficient $\unicode[STIX]{x1D70C}(x)$, integral length scale $L(x)$ and the dissipation coefficient $C_{\unicode[STIX]{x1D716}}(x)$, a simple turbulent kinetic energy model is proposed that describes the evolution of our grid generated turbulence field using one centreline measurement and one vertical profile of $u^{\prime }(y)$ at the beginning of the evolution. The results calculated from our model agree well with our measurements in the streamwise extent up to $x/H\approx 2.5$, where $H$ is the height of the grid, suggesting that it might be possible to design some shear flows with desired mean velocity and turbulence intensity profiles by designing the geometry of a passive grid.

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Methods of producing velocity profiles in wind tunnels

Cited by 11 publications

References 10 publications

Simulation of twisted wind flows in a boundary layer wind tunnel for pedestrian-level wind tunnel tests

Simulation of twisted wind flows in a boundary layer wind tunnel for pedestrian-level wind tunnel tests

Experimental studies on the instantaneous fluid–structure interaction of an air-inflated flexible membrane in turbulent flow

Weakly sheared turbulent flows generated by multiscale inhomogeneous grids

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