An experimental study on cross-flow mixing in a rod-bundle geometry using a wire-mesh. Bulk, F., P. In Proc. 15th Int. Topl. Mtg. Nuclear Reactor Thermal Hydraulics (NURETH-15), 2012.
abstract   bibtex   
The flow of water through a reactor core is of interest for various reasons associated with reactor safety and efficiency. In order to gain more insight into the behavior of this flow, this work aims to measure characteristics of the single-phase turbulent flow in this geome- try. For this purpose, a wire-mesh measurement equipment was chosen. The wire-mesh is a conductivity-based measurement equipment that so far has mainly been used for measure- ments in gas-liquid flows. Because this research focuses on single-phase flows, first, the capabilities of a wire-mesh in a single-phase flow were investigated using a simple pipe geometry. In this setup, the radial dispersion of a tracer injected in the center of the pipe was looked at. The calibration method of the signal was investigated, methods of improving the capabilities of the equipment were looked at and its reliability and accuracy were investigated. In particular, it was found that the use of added resistors to increase the measuring range of the equipment is problematic and, therefore, is not recommended. Values for the tracer concentration and dispersion as a function of Reynolds number and travel distance in the tube were investigated and com- pared to literature. The results are in a good agreement with the literature. Furthermore, the large-scaled turbulence structures were visualized and quantified with the help of the power spectra of the concentration fluctuations in the wire-mesh. The behavior and size of these structures was as expected, and consistent with the results found in literature. Aside from the more general research on the measurement technique, in the second part of this work research was performed with the aim of investigating the possibilities and limita- tions of the wire-mesh technique for concentration measurements and mixing information in a rod-bundle geometry. For this purpose, a custom-designed wire-mesh was constructed and installed in the rod-bundle geometry. The wire-mesh was designed and constructed in- house, and specifically made for an existing rod-bundle geometry. Special care was taken in order to minimize the flow disturbance introduced by the measurement equipment. Some initial experiments were performed with this equipment. The measured dispersion shows a good signal without negative influence from any possible disturbances in the flow due to the measurement equipment or injection capillary. The reliability of the signals was looked at, and some first attempt were done in quantifying the size of the large scale coherent structures in the flow. This quantification shows a consistent behavior, with a reasonable agreement with the literature. The experimental work was performed at the ’Kramers Laboratorium voor Fysische Tech- nology’ as a part of an on-going collaboration between the departments of Mutiscale Physics and Physics of Nuclear Reactors.
@inproceedings{
 title = {An experimental study on cross-flow mixing in a rod-bundle geometry using a wire-mesh},
 type = {inproceedings},
 year = {2012},
 city = {Pisa, Italy},
 id = {89f8a878-1eb5-353c-aa6b-63dfad34a41b},
 created = {2018-06-29T18:31:10.038Z},
 file_attached = {false},
 profile_id = {51877d5d-d7d5-3ec1-b62b-06c7d65c8430},
 group_id = {efaa6fc9-0da5-35aa-804a-48d291a7043f},
 last_modified = {2018-10-02T09:30:06.134Z},
 read = {false},
 starred = {false},
 authored = {false},
 confirmed = {true},
 hidden = {false},
 citation_key = {Bulk2012},
 source_type = {CONF},
 private_publication = {false},
 abstract = {The flow of water through a reactor core is of interest for various reasons associated with reactor safety and efficiency. In order to gain more insight into the behavior of this flow, this work aims to measure characteristics of the single-phase turbulent flow in this geome- try. For this purpose, a wire-mesh measurement equipment was chosen. The wire-mesh is a conductivity-based measurement equipment that so far has mainly been used for measure- ments in gas-liquid flows. Because this research focuses on single-phase flows, first, the capabilities of a wire-mesh in a single-phase flow were investigated using a simple pipe geometry. In this setup, the radial dispersion of a tracer injected in the center of the pipe was looked at. The calibration method of the signal was investigated, methods of improving the capabilities of the equipment were looked at and its reliability and accuracy were investigated. In particular, it was found that the use of added resistors to increase the measuring range of the equipment is problematic and, therefore, is not recommended. Values for the tracer concentration and dispersion as a function of Reynolds number and travel distance in the tube were investigated and com- pared to literature. The results are in a good agreement with the literature. Furthermore, the large-scaled turbulence structures were visualized and quantified with the help of the power spectra of the concentration fluctuations in the wire-mesh. The behavior and size of these structures was as expected, and consistent with the results found in literature. Aside from the more general research on the measurement technique, in the second part of this work research was performed with the aim of investigating the possibilities and limita- tions of the wire-mesh technique for concentration measurements and mixing information in a rod-bundle geometry. For this purpose, a custom-designed wire-mesh was constructed and installed in the rod-bundle geometry. The wire-mesh was designed and constructed in- house, and specifically made for an existing rod-bundle geometry. Special care was taken in order to minimize the flow disturbance introduced by the measurement equipment. Some initial experiments were performed with this equipment. The measured dispersion shows a good signal without negative influence from any possible disturbances in the flow due to the measurement equipment or injection capillary. The reliability of the signals was looked at, and some first attempt were done in quantifying the size of the large scale coherent structures in the flow. This quantification shows a consistent behavior, with a reasonable agreement with the literature. The experimental work was performed at the ’Kramers Laboratorium voor Fysische Tech- nology’ as a part of an on-going collaboration between the departments of Mutiscale Physics and Physics of Nuclear Reactors.},
 bibtype = {inproceedings},
 author = {Bulk, Frederick Pieter},
 booktitle = {Proc. 15th Int. Topl. Mtg. Nuclear Reactor Thermal Hydraulics (NURETH-15)}
}

Downloads: 0