Vortex-meter design: The influence of shedding-body geometry on shedding characteristics

Ford, Christopher L.; Winroth, P. Marcus; Alfredsson, P. Henrik

doi:10.1016/j.flowmeasinst.2017.12.004

Cited by 5 publications

(17 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is postulated that the presence of the vortex shedder induces a periodic separation at the pipe wall and this is responsible for the mode-II frequency. Ford et al (2018) demonstrate numerous pieces of evidence for this; a reduction in near-wall Mach number downstream of the shedder when mode-II is present, for example.…”

Section: Mode-iimentioning

confidence: 98%

“…Mode interaction is clearly an important factor in confined bluff-body flows, which may lead to the complete disruption of the principal shedding mode. Using the hypothesis for the interaction mechanism laid out by Ford et al (2018) and the observations of the scaling behaviour of mode-II presented in this section allows a more complete picture of how to avoid (or indeed encourage) mode interaction.…”

Section: Mode-iimentioning

confidence: 99%

“…A recent work by Ford, Winroth & Alfredsson (2018) examined the influences of shedder geometry on vortex shedding of confined bluff bodies. The study highlighted a bi-modal behaviour: mode-I was associated with shedding of the primary vortex, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…For certain geometries and Reynolds numbers, modes-I and II interact and in some cases mode-I locks-on to the mode-II frequency. Ford et al (2018) hypothesised that this can only occur if the length scales of mode-I and mode-II are in sufficient proportion (i.e. the length scale of mode-II must be large enough) and the frequency ratio is 1020 C. L. Ford and P. M. Winroth close to an integer value.…”

Section: Introductionmentioning

confidence: 99%

“…the length scale of mode-II must be large enough) and the frequency ratio is 1020 C. L. Ford and P. M. Winroth close to an integer value. A detailed description and theoretical model is presented by Ford et al (2018).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

On the scaling and topology of confined bluff-body flows

Ford

Winroth

2019

J. Fluid Mech.

View full text Add to dashboard Cite

An experimental study of bluff bodies in confinement is presented. Two Reynolds matched rigs (pipe diameters: $D=40~\text{mm}$ and $D=194~\text{mm}$) are used to derive a picture of the flow topology of the primary-shedding mode (Kármán vortex, mode-I). Confined bluff bodies create an additional spectral mode (mode-II). This is caused by the close coupling of the shedder blockage and the wall and is unique to the confined bluff-body problem. Under certain conditions, modes-I and II can interact, resulting in a lock-on, wherein the modes cease to exist at independent frequencies. The topological effects of mode interaction are demonstrated using flow visualisation. Furthermore, the scaling of mode-II is explored. The two experimental facilities span Reynolds numbers (based on the shedder diameter, $d$) $10^{4}<Re_{d}<10^{5}$ and bulk Mach numbers $0.02<M_{b}<0.4$. Bluff bodies with a constant blockage ratio ($d/D$), forebody shape and various splitter-plate lengths ($l$) and thicknesses ($t$) are used. Results indicate that the flow topology changes substantially between short ($l<d$) and long ($l>d$) tailed geometries. Surface flow visualisation indicates that the primary vortex becomes anchored on the tail when $l\gtrsim 3h$ ($2h=d-t$). This criterion prohibits the development of such a topology for short-tailed geometries. When mode interaction occurs, which it does exclusively in long-tailed cases, the tail-anchored vortex pattern is disrupted. The onset of mode-II occurs at approximately the same Reynolds number in both rigs, although the associated dimensionless frequency is principally a function of Mach number. Accordingly, mode interaction is avoided in the larger-scale rig, due to the increased separation of the modal frequencies.

show abstract

Section: Mode-iimentioning

confidence: 98%

Section: Mode-iimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations