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| NKS Programme Area: | NKS-R | | Research Area: | Thermal hydraulics | | Report Number: | NKS-280 | | Report Title: | PIV MEASUREMENTS AT THE BLOWDOWN PIPE OUTLET | | Activity Acronym: | ENPOOL | | Authors: | Markku Puustinen, Jani Laine, Antti Räsänen, Lauri Pyy, Joonas Telkkä, | | Abstract: | This report summarizes the findings of the PIV measurement tests carried out in January – February 2013 with the scaled down PPOOLEX test facility at LUT. The main objective of the tests was to find out the operational limits of the PIV system regarding suitable test conditions and correct values of different adjustable PIV parameters. An additional objective was to gather CFD grade data for verification/validation of numerical models. Both water and steam injection tests were carried out. PIV measurements with cold water injection succeeded well. Raw images were of high quality, averaging over the whole measurement period could be done and flow fields close to the blowdown pipe outlet could be determined. In the warm water injection cases the obtained averaged velocity field images were harder to interpret, especially if the blowdown pipe was also filled with warm water in the beginning of the measurement period. The absolute values of the velocity vectors seemed to be smaller than in the cold water injection cases. With very small steam flow rates the steam/water interface was inside the blowdown pipe and quite stable in nature. The raw images were of good quality but due to some fluctuation in the velocity field averaging of the velocity images over the whole measured period couldn’t be done. Condensation of steam in the vicinity of the pipe exit probably caused these fluctuations. A constant outflow was usually followed by a constant inflow towards the pipe exit. Vector field images corresponding to a certain phase of the test could be extracted and averaged but this would require a very careful analysis so that the images could be correctly categorized. With higher steam flow rates rapid condensation of large steam bubbles created small gas bubbles which were in front of the measurement area of the PIV system. They disturbed the measurements by reflecting laser light like seeding particles and therefore the raw images were of poor quality and they couldn’t be processed correctly. Experiments in the PPOOLEX facility form a very challenging environment for the use of the PIV measurement system. Some observations regarding the suitability of the system for different kind of flow situations can be made on the basis of the tests reported here. However, the full capacity of the system must be determined later on the basis of a more comprehensive experiment series | | Keywords: | condensation pool, steam/air blowdown, thermal stratification and mixing | | Publication date: | 01 May 2013 | | ISBN: | ISBN 978-87-7893-355-3 | | Number of downloads: | 4082 | | Download: |  NKS-280.pdf |
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