Turbulent and laminar heat transfer to gases with varying properties in the entry region of circular ducts

Bankston, C.A.; McEligot, Donald M.

doi:10.1016/0017-9310(70)90110-9

Cited by 94 publications

(36 citation statements)

References 16 publications

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“…The coefficients are pref = 0.074321 lbm/fi?, pref = 1.2391 x 10-5 lbm/ftsec, Cppf = 0.24 Btu/lbmF and Href = 0 Btu/lbm, respectively. These property relations are consistent with the nomenclature in the predictive program by Bankston and McEligot [1970].…”

Section: B 1 Calculation Proceduressupporting

confidence: 85%

“…They further supplement and extend earlier data for internal turbulent flows in sinal1 tubes with temperature dependent transport properties that could only provide integral parameters, such as local Nusselt numbers and local skin friction coefficients. These earlier data gave initial tests of turbulence models accounting for temperature-dependent transport properties, as demonstrated by Bankston and McEligot [1970] and Kawamura [1979]. The current data also complement measurements by Steiner [ 19711 and Carr, Connor and Buhr [1973] who used "large" tubes for mean profile measurements so buoyancy forces probably dominated their flows.…”

Section: Introductionsupporting

confidence: 77%

“…One may calculate apparent local friction friction factors from these data; these are the friction factors one obtains from one-dimensional measurements without profile data -as explained by McEligot [1963] and Bankston and McEligot [1970]. These fapp values can be expected to differ from fs = p,w(aU/ay)~ / (G2/2pbgc) as usually calculated by analysts.…”

Section: A -2mentioning

confidence: 97%

“…The range 0 < y/rw < 0.5 was selected for presentation, corresponding to 0 < y+ < 40 at the exit (and yf < 100 at the start of heating). These numerical predictions were obtained by applying the finite control volume program of Bankston and McEligot [1970] with the addition of a body force term in the momentum equation. There is no direct functional accounting for buoyancy effects in the turbulence model itself; however, adjustment of the turbulence model for flows in this range of parameters would imply indirect allowance for buoyancy effects.…”

Section: Distribution Of Mean Turbulence Quantitites In Conventional mentioning

confidence: 99%

“…The wall coordinates are defined in terms of fluid properties evaluated at the wall temperature, pw = p{TW}, cPIw = cp{Tw} and so forth, as by Bankston and McEligot [1970]. Once these properties are evaluated and ZW is determined via fs = (fs/fDKM) fDKM, calculation of UT, y+w, U+W and t+w from their definitions is straight forward.…”

Section: B-5mentioning

confidence: 99%

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Turbulence structure in the viscous layer of strongly heated gas flows

Shehata

McEligot

1995

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For dominant forced convection with significant gas property variation, even in low Mach number flow through a circular tube, apparently the only published profile data available to guide (or test) the development of predictive turbulence models are K. R. Perkins' measurements of mean temperature structure [Perkins, 19751. The work here takes the next step: the frrst mean velocity distributions for this situation are presented.In order to dissect the anatomy of the viscous layer in gaseous, turbulent, tubie flow with strong heating, it has been probed via thermal anemometry coupled with diagnostic application of simple computational thermal fluid dynamics. Experiments for air flowing upward in a vertical circular tube were conducted for heating rates causing significant property variation. An unheated entry of fifty diameters preceeded the heating.Two entry Reynolds numbers of approximately 6000 and 4000 were employed, concentrating on three heating rates, q+ = q"w/Gcp,inTin = 0.0018, 0.00135 and 0.0045, to give conditions considered to be "turbulent," "subturbulent" and "laminarizing," respectively. Exit Reynolds numbers were above 3000 in all cases.Examination emphasizes the wall region which would conventionally be expected to contain the viscous layer, 0 < y+ < -30, if the flow were unheated. In the flow called "turbulent", after being disturbed in the first few diarneters by the heating (and its accompanying variation of viscosity, density and thermal conductivity), profiles representing the turbulence quantities --l/y, E /v, -p UV /'cw and -pc+ 5 /qtvw --appear to recover to approximately selfpreserving conditions. In the other two runs with higher heating rates, the turbulence quantities decrease after the immediate thermal entrance until they are small relative to molecular effects. m DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use wouid not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, rnanufacturer, or otherwise does not necessarily constitute or imply its endorsement, m mmendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors ~XPT~SSUI herein do not necessarily state or reflect those of the United States Government or any agency thereof.

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Section: B 1 Calculation Proceduressupporting

confidence: 85%

Section: Introductionsupporting

confidence: 77%

Section: A -2mentioning

confidence: 97%

Section: Distribution Of Mean Turbulence Quantitites In Conventional mentioning

confidence: 99%

Section: B-5mentioning

confidence: 99%

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