Abstract
T-junction is one of the familiar components in the cooling system of power plants with enormous capability of high-cycle thermal fatigue. This research investigates the structure and mixing mechanism of turbulent flow in a T-junction area with a 90 deg bend upstream. According to the wide distribution of turbulent jets in the T-junction, a reattached jet was selected previously as the best representative condition with the highest velocity fluctuation and the most complex structure. For considering the mixing mechanism of re-attached jet, T-junction is subdivided into few lateral and longitudinal sections, and each section is visualized separately by particle image velocimetry technique. Corresponding to the experimental data, the branch flow acts as a finite turbulent jet, develops the alternative type of eddies, and causes the high velocity fluctuation near the main pipe wall. Three regions are mainly subject to maximum velocity fluctuation: the region close to the jet boundaries (fluctuation mostly is caused by Kelvin-Helmholtz instability), the region above the jet and along the main flow (fluctuation mostly is caused by Karman vortex), and the re-attached area (fluctuation mostly is caused by changing the pressure gradient in the wake area above the jet). Finally, the re-attached area (near the downstream of wake area above the jet) is introduced as a region with strongest possibility to high-cycle thermal fatigue with most effective velocity fluctuation on the main pipe wall above the branch nozzle.
Original language | English |
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Pages (from-to) | 511031-511037 |
Number of pages | 7 |
Journal | Journal of Fluids Engineering, Transactions of the ASME |
Volume | 131 |
Issue number | 5 |
DOIs | |
Publication status | Published - 2009 May 1 |
Keywords
- Fluid mixing structure and interaction
- Mixing tee
- PIV
- Piping system
- Turbulent Flow
ASJC Scopus subject areas
- Mechanical Engineering