Abstract:The flow field behind attached ring-type turbulence promoters of various sizes in a smooth pipe has been investigated by measuring the mean velocity and turbulence intensity profiles for downstream distances up to 100 promoter heights at a Reynolds number of 20 500 (based on pipe diameter and average velocity). Measurements have been limited to distances downstream of the flow reattachment region. The results indicate that for the smallest tested promoter with nondimensional height h+=12.5, the disturbance int… Show more
“…It is postulated that signi"cant interaction between the two obstacles can exist only if the #ow reaching the downstream one has not recovered fully its equilibrium condition. For the case of developed turbulent #ow, the typical length of the separated region behind a very thin obstacle is 8}12 times its height h, while recovery may well require an additional length of 10}15h (Bullock et al 1990;Scho"eld & Logan 1990;Liou et al 1990). These lengths can be compared to the experimental bounds obtained for l R /h and l K /h and shown in Table 1.…”
Section: A Model For the Behaviour Of The Systemmentioning
“…It is postulated that signi"cant interaction between the two obstacles can exist only if the #ow reaching the downstream one has not recovered fully its equilibrium condition. For the case of developed turbulent #ow, the typical length of the separated region behind a very thin obstacle is 8}12 times its height h, while recovery may well require an additional length of 10}15h (Bullock et al 1990;Scho"eld & Logan 1990;Liou et al 1990). These lengths can be compared to the experimental bounds obtained for l R /h and l K /h and shown in Table 1.…”
Section: A Model For the Behaviour Of The Systemmentioning
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