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|NKS Programme Area:||NKS-R|
|Research Area:||Thermal Hydraulics|
|Report Title:||PIV Measurements of DCC-06 and DCC-07 PPOOLEX Experiments|
|Authors:||Lauri Pyy, Joonas Telkkä, |
|Abstract:||This report summarizes the results of the DCC-06 and DCC-07 steam discharge experiments carried out with the scaled down PPOOLEX test facility designed and constructed at Lappeenranta University of Technology. Steam was blown through the vertical DN100 blowdown pipe to the condensation pool filled with sub-cooled water.
The main objective of the experiments was to use the PIV measurement system in different direct contact condensation situations in order to obtain velocity field data to be used in verification of CFD simulation results.
Both experiments consisted of several PIV measurement sequences, where different steam flow rates and pool water temperatures were used. Most of the time the steam/water interface moved up and down along the blowdown pipe as a result of rapid condensation taking place either inside the pipe or at the pipe outlet. There was only a short period of time in DCC-06, when the steam/water interface was quite calm at the blowdown pipe outlet.
Steam release into the pool water created major optical problems for the PIV measurements. The problems couldn’t be avoided even with the new red band pass filters. Time-averaging of the PIV images did not work due to the fluctuating behaviour of the water phase. Therefore, the PIV results from the DCC-06 and DCC-07 experiments can be presented only as individual vector images from those measurement sequences where optically intact raw images are available. It is possible to measure the velocity field of the water phase, but only from areas where condensing does not occur.
The main finding from the DCC-06 and DCC-07 experiments is that PIV cannot be applied successfully for velocity measurements near the blowdown pipe outlet with the current PPOOLEX measuring set-up. The character of the flow in most steam discharge experiments is fluctuating and chaotic. These fluctuations make the time-averaging of PIV images impossible because there is no constant flow direction to be found. In addition, when there are optical distortions present, the PIV vector result is corrupted. At the moment there is not a way to get around these optical distortions even though the new filters succeeded well by cutting the reflections from the actual steam bubbles.|
|Keywords:||condensation pool, steam blowdown, PIV measurements|
|Publication date:||01 Apr 2015|
|Number of downloads:||1281|