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Title: Mixed convection heat transfer to and from a horizontal cylinder in cross-flow with heating from below.

Abstract

Heat transfer to and from a circular cylinder in a cross-flow of water at low Reynolds number was studied both experimentally and numerically. The experiments were carried out in a high aspect ratio water channel. The test section inflow temperature and velocity, channel lower surface temperature and cylinder surface temperature were controlled to yield either laminar or turbulent flow for a desired Richardson number. When the lower surface was unheated, the temperatures of the lower surface and water upstream of the cylinder were maintained approximately equal and the flow was laminar. When the lower surface was heated, turbulence intensities as high as 20% were measured several cylinder diameters upstream of the cylinder due to turbulent thermal plumes produced by heating the lower surface. Variable property, two-dimensional simulations were undertaken using a variant of the u{sup 2}-f turbulence model with buoyancy production of turbulence accounted for by a simple gradient diffusion model. Predicted and measured heat flux distributions around the cylinder are compared for values of the Richardson number, Gr{sub d}/Re{sub d}{sup 2} from 0.3 to 9.3. For laminar flow, the predicted and measured heat flux results agreed to within the experimental uncertainty. When the lower surface was heated, and themore » flow was turbulent, there was qualitative agreement between predicted and measured heat flux distributions around the cylinder. However the predicted spatially averaged Nusselt number was from 37% to 53% larger than the measured spatially averaged Nusselt number. Additionally, spatially averaged Nusselt numbers are compared to correlations in the literature for mixed convection heat transfer to/from cylinders in cross-flow. The results presented here are larger than the correlation values. This is believed to be due to the effects of buoyancy-induced turbulence resulting from heating the lower surface and the proximity of the cylinder to that surface.« less

Authors:
 [1]; ;  [2];
  1. (University of California, Berkeley, CA)
  2. (Sandia National Laboratories, Albuquerque, NM)
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
952100
Report Number(s):
SAND2006-0969J
TRN: US200913%%296
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proposed for publication in the International Journal of Heat and Fluid Flow.
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; CONVECTION; HEAT TRANSFER; CYLINDERS; LAMINAR FLOW; TURBULENT FLOW; NUSSELT NUMBER; REYNOLDS NUMBER; RICHARDSON NUMBER; FLOW MODELS; TEMPERATURE MEASUREMENT

Citation Formats

Greif, Ralph, Evans, Gregory Herbert, Kearney, Sean Patrick, and Laskowski, Gregory Michael. Mixed convection heat transfer to and from a horizontal cylinder in cross-flow with heating from below.. United States: N. p., 2006. Web.
Greif, Ralph, Evans, Gregory Herbert, Kearney, Sean Patrick, & Laskowski, Gregory Michael. Mixed convection heat transfer to and from a horizontal cylinder in cross-flow with heating from below.. United States.
Greif, Ralph, Evans, Gregory Herbert, Kearney, Sean Patrick, and Laskowski, Gregory Michael. Wed . "Mixed convection heat transfer to and from a horizontal cylinder in cross-flow with heating from below.". United States. doi:.
@article{osti_952100,
title = {Mixed convection heat transfer to and from a horizontal cylinder in cross-flow with heating from below.},
author = {Greif, Ralph and Evans, Gregory Herbert and Kearney, Sean Patrick and Laskowski, Gregory Michael},
abstractNote = {Heat transfer to and from a circular cylinder in a cross-flow of water at low Reynolds number was studied both experimentally and numerically. The experiments were carried out in a high aspect ratio water channel. The test section inflow temperature and velocity, channel lower surface temperature and cylinder surface temperature were controlled to yield either laminar or turbulent flow for a desired Richardson number. When the lower surface was unheated, the temperatures of the lower surface and water upstream of the cylinder were maintained approximately equal and the flow was laminar. When the lower surface was heated, turbulence intensities as high as 20% were measured several cylinder diameters upstream of the cylinder due to turbulent thermal plumes produced by heating the lower surface. Variable property, two-dimensional simulations were undertaken using a variant of the u{sup 2}-f turbulence model with buoyancy production of turbulence accounted for by a simple gradient diffusion model. Predicted and measured heat flux distributions around the cylinder are compared for values of the Richardson number, Gr{sub d}/Re{sub d}{sup 2} from 0.3 to 9.3. For laminar flow, the predicted and measured heat flux results agreed to within the experimental uncertainty. When the lower surface was heated, and the flow was turbulent, there was qualitative agreement between predicted and measured heat flux distributions around the cylinder. However the predicted spatially averaged Nusselt number was from 37% to 53% larger than the measured spatially averaged Nusselt number. Additionally, spatially averaged Nusselt numbers are compared to correlations in the literature for mixed convection heat transfer to/from cylinders in cross-flow. The results presented here are larger than the correlation values. This is believed to be due to the effects of buoyancy-induced turbulence resulting from heating the lower surface and the proximity of the cylinder to that surface.},
doi = {},
journal = {Proposed for publication in the International Journal of Heat and Fluid Flow.},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2006},
month = {Wed Feb 01 00:00:00 EST 2006}
}