Prediction of strongly-heated internal gas flows Page: 1 of 17
15 p.View a full description of this article.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
I A4114AI -97- >,134
PREDICTION OF STRONGLY-HEATED INTERNAL GAS FLOWS
Donald M. McEligotl,2,3, A. Mohsen Shehata4 and Tomoaki Kunugi3,5 CA/OAF- 9 'o ---1.
2.
3.
4.
5.ABSTRACT
Idaho National Engineering and Environmental Laboratory / LMITCo, Idaho Falls, Ida. USA
University of Arizona, Tucson, Ariz., USA
Japan Atomic Energy Research Institute, Tokai, Ibaraki, Japan
Xerox Corporation, Webster, N. Y., USA
Tokai University, Hiratsuka, Kanagawa, JapanOSTI
The purposes of the present article are to remind practitioners why the usual textbook approaches may not be
appropriate for treating gas flows heated from the surface with "large" heat fluxes and to review the successes of some
recent applications of turbulence models to this case. Simulations from various turbulence models have been assessed
by comparison to the measurements of internal mean velocity and temperature distributions by Shehata for turbulent,
laminarizing and intermediate flows with significant gas property variation. Of about fifteen models considered, five
were judged to provide adequate predictions.1. INTRODUCTION
Gas cooling of heated surfaces offers the advantages of
inherent safety, environmental acceptability, chemical
inertness, high thermal efficiency and a high
temperature working fluid for electrical energy
generation and process heating. Consequently, helium
and other gas systems are considered as coolants for
advanced power reactors, both fission and fusion.
Cooling of a gas is important in gas turbine engine and
rocket propulsion systems. These applications have in
common turbulent flow with significant gas
temperature variation along and/or across the cooling
channels.
The purposes of the present article are (1) to
remind practitioners why the usual textbook approaches
may not be appropriate for treating gas flows heated
from the surface with "large" heat fluxes and (2) to
review the successes (and failures) of some recent
applications of turbulence models to this case. Some
observations will also be pertinent to cooling of a gas
as well. The main message is one of caution to thermal
engineers, even for apparently simple cases.
There are enough effects induced by large heat
fluxes so that, to concentrate on them and avoid further
complications, this paper considers only steady state
conditions in a simple geometry: the classical
axisymmetric circular tube. The heated region is
preceded by a flow development region which yields an
approximately fully-developed turbulent velocity
profile; heating is then by an approximately uniform
wall flux, as from electrical resistance heating. No
internal energy generation is treated. The case is further
constrained to small tubes, low densities and/or
microgravity applications so buoyancy effects are not
important; that is, the situation represents dominant
forced convection. As a first warning, Figure 1
demonstrates the dangers of blind application of
recommended "general purpose," commercial computer
codes for this limited case (a version of a popular
commercial code has been used on a typical engineer's
work station).
DISTRIBUTION OF THIS DOCUMENT IS UNIMiEBoo
0
Data of Shehata o
*
0
-- commercial code
Run 635
o *
S 0 5 10 , x0 D
X/ DFigure 1 Numerical prediction from commercial
general-purpose CTFD code, at conditions of Shehata's
Run 635, compared to his measurements.
For a summary of Western studies to about
1982 on the effects of property variation on turbulent
and laminar internal gas flows, the reader is referred to
an earlier review by McEligot [1986]. While not all-
inclusive and concentrating primarily on forced
convection, this review can provide a useful
introduction to the subject. The present study does not
consider particle-laden gas flows; for studies of this
promising technique, the reader is referred to the review
of Hasegawa, Echigo and Shimizu [1986]. Reviews of
mixed convection in vertical tubes are presented by
Jackson and coworkers [Jackson, Cotton and Axcell,
1989; Cotton and Kerwin, 1995]. Useful reviews of
the status of numerical prediction techniques for
turbulent flows have been published by Nagano and
Shimada [1995] and Iacovides and Launder [1995].
Nagano and Shimada relate modeling techniques to
Direct Numerical Simulations (DNS) and their
potential. Iacovides and Launder relate their study to
applications for internal cooling passages of gas turbine
blades, a complicated problem with some features of the
present study; of particular interest is their conclusion
MASTER
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
McEligot, D. M.; Shehata, A. M. & Kunugi, Tomoaki. Prediction of strongly-heated internal gas flows, article, December 31, 1997; Idaho Falls, Idaho. (https://digital.library.unt.edu/ark:/67531/metadc691775/m1/1/: accessed July 16, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.