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This content will become publicly available on August 10, 2018

Title: Jet stability and wall impingement flow field in a thermal striping experiment

We present velocity and temperature field measurements for a 0.9 x 0.9 x 1.7 m glass tank in which two air jets at Re=10000 mix and impinge upon the lid at ambient temperature and pressure. Flow patterns are characterized across a 350 x 200 mm plane located 3 mm below the lid for two inlet geometries: 1) “extended”, in which inlet channels protrude above the tank base, and 2) “flush”, a flat base without protrusions. This minor geometry variation produced distinct changes in the lid flow field, appearing as three stagnant regions for the extended case and only one for flush. The dichotomy is attributed to system stability characteristics: jets are stable in the extended case and unstable for flush. In a separate set of nonisothermal tests, the impingement temperature field was measured for inlet temperature mismatches of 4 oC and jets near Re=10000. A 50 m-long fiber optic distributed temperature sensor positioned 2 mm below the lid measured at 1350 locations. Like the velocity fields, the temperature fields differ for the two inlet geometries: good thermal mixing for the flush case and subdued mixing for the extended case. Simulations with the spectral element code Nek5000 replicated the observed stabilitymore » dichotomy, duplicating the number of stagnant regions observed in the experiment and matching their locations within ±10 mm. Simulation data suggests that flush case instability is due to interactions between jets and wall flows at the bottom of the tank. The clear flow dichotomy exhibited by this two-jet setup presents an unambiguous case to test the ability of CFD tools to predict subtle flow field changes driven by minor modifications in geometry in the context of thermal striping.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
International Journal of Heat and Mass Transfer
Additional Journal Information:
Journal Volume: 115; Journal Issue: Part A; Journal ID: ISSN 0017-9310
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE; USDOE Office of Nuclear Energy, Nuclear Energy Advanced Modeling and Simulation (NEAMS)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; CFD validation; experiment; thermal striping; Nek5000; PIV; fiber optic distributed temperature sensor; jet impingement; CFD Validation; NeK5000
OSTI Identifier:
1376554
Alternate Identifier(s):
OSTI ID: 1379164