Wind tunnel modelling as a means of predicting the response of chimmeys to vortex shedding

The effect of free-stream turbulence on sectional lift forces on a circular cylinder

“…It can be seen that these two experimental values extend the range of the turbulence parameter Ta above the full scale results, and that the values of C l follow the trend established by the full scale results. Estimates of sectional coefficients of lift C l and turbulence parameter Ta = Iu (L x u /D) −1/3 presented by Vickery and Daly (1984), together with values obtained at the upper end of the Reynolds number range (Re ≈ 5 × 10 5 ) in the present experiments.…”

“…There was substantial, but not dominant, energy at low frequencies, due to the buffeting effects of turbulence. Sanada & Nakamura (1983) and Sanada, Suzuki & Matsumoto (1992) published results measured on a 200 m high reinforced concrete stack; the readings were obtained from pressure tappings installed at an elevation of 140 m where the diameter was 15 m. The results have also been reproduced and discussed by Vickery & Daly (1984) and Vickery (1991). The surface roughness for this structure is not known, but is likely to be comparable to that for the Hamburg television tower.…”

“…Over the range of Reynolds numbers from 1 × 10 7 to 4 × 10 7 , C l dropped from approximately 0.4 to 0.07. Vickery & Daly (1984) and Vickery (1991) suggested that this drop could was correlated not with increase in Reynolds number but with a decrease in turbulence intensity, as assessed from the ratio C d /C d . Since a large proportion of the overall lift was due to vortex shedding as opposed to buffeting, it was suggested turbulent energy in the mean flow was able to enhance the forces produced by vortex shedding.…”

“…The effect of turbulence on flows in the transcritical Reynolds regime has received little systematic study, but data from a small number of full-scale experiments suggest that free-stream turbulence may also produce higher force coefficients in the transcritical regime (Vickery & Daly 1984). This effect can be partially attributed to low-frequency cross-flow buffeting by free-stream turbulence; however examination of lift spectra suggest that another, as yet unknown, mechanism also serves to increase lift force spectral density at the Strouhal frequency in the transcritical regime.…”

Field Tests on a Full-Scale Steel Chimney Subjected to Vortex-Induced Vibrations

“…VIV models are numerous and codified methods can be found in many standards but their ability to capture the VIV amplitude response at super-critical Reynolds numbers and with real atmospheric boundary layers needs validation. Wind tunnels are also important in response prediction though the scaled models can cause cross-wind loads to be highly overestimated [29]. A method for overcoming the scaling effect is to artificially increase the Reynolds number by adding surface roughness to the cylinder's surface [20,21].…”