Refine your search�ソスF     
Report No.
 - 

Order of Magunitude Analysis of stratified natural convection and mixed convection penetration flow of cold liquid into a vertical channel with hot,forced flow

Tokuhiro, Akira; Kobayashi, Jun 

In the thermal-hydraulic analysis of nuclear reactors and other energy-related systems, the proper scaling of simulation experiments and separate effect studies, is first determined by the identification of the relevant dimensionless group(s) and then by the reproduction in magnitude of the range. While most experiments contain some idealizations in geometry so that well-known dimensionless groups can be easily identified, the non-ideal nature of any given experiment may appear for instance, in the presentation of data using the selected dimensionless numbers. If this is the case, a reconsideration of the Scale Analysis or Order of Magnitude Analysis (OMA) may reveal slight modifications to classic results that originate from ideal cases. The present work summarizes OMA by way of example; that is, a reconsideration of the stratified natural convection problem from which a stratified Nusselt number is introduced. Two data sets are presented in support of the described modification. This is then followed by an experimental investigation on penetration of cold liquid into a modeled subassembly channel under mixed convection, from the hot plenum of a protypicaI FBR design. The penetration phenomenon occurs under certain natural circulation conditions during the operation of the DRACS (direct reactor auxilialy cooling system) for decay heat removal and can influence the natural circulation head that determines the core flow rate and consequently the core cooling rate. In the present experiment, a simplified test section simulating the upper plenum and a subassembly channel was constructed wherein both temperature and velocity measurements were made to investigate the penetration of cold water into a vertical channel with upward flowing hot water. Upon comparing temperature and velocily data we found an overall similarity in their respective spatio-temporal distributions as expected. The data suggested correlations describing the onset of flow penetration and ...

Acecsses

:

- Accesses

InCites™

:

Altmetrics

:

[CLARIVATE ANALYTICS], [WEB OF SCIENCE], [HIGHLY CITED PAPER & CUP LOGO] and [HOT PAPER & FIRE LOGO] are trademarks of Clarivate Analytics, and/or its affiliated company or companies, and used herein by permission and/or license.