Abo Bibliothek: Guest

ISSN Online: 2377-424X

ISBN Print: 0-89116-130-9

International Heat Transfer Conference 6
August, 7-11, 1978, Toronto, Canada

TURBULENT INTERCHANGE IN TRIANGULAR ARRAY BARE ROD BUNDLES

Get access (open in a dialog) DOI: 10.1615/IHTC6.3390
pages 11-16

Abstrakt

Bulk mixing coefficients were measured for single phase water flows in a six channel simulated rod bundle with a pitch to diameter ratio of 1.10. A tracer technique employing Rhodamine B as the tracer and measuring fluorescence was used. Isokinetic sampling was achieved using a pressure balance method. Sub¬channel bulk exit concentrations were measured at two axial locations (L/De = 44.5 and 92.5). During each test the central subchannels were alternately traced so that mixing rates were determined for both directions (wij and wji). These results were corrected for both entrance effects and diversion cross-flows through the use of a subchannel analysis code.
Our results showed a change in Reynolds number behavior as the laminar sublayer began to "choke" the turbulent mixing. This, and a review of the experimental procedure used in other mixing experiments, suggested that secondary flows may not compensate for laminarization and that turbulent mixing decreases as the pitch to diameter ratio decreases for values of P/D less than 1.05 in a manner similar to that predicted by Ramm, et al.
Concentration profiles were measured through the clearance gap and the gap concentration gradients were calculated. The mixing coefficients from the bulk tests were combined with these gradients and the definition of the mixing coefficient to calculate the gap averaged circumferential eddy diffusivities for mass (∈m∅).