Detailed steady and unsteady numerical studies were performed to investigate tip clearance flow in an axial water jet pump. The primary objective is to understand physics of unsteady tip clearance flow, unsteady tip leakage vortex, and cavitation inception in an axial water jet pump. Steady pressure field and resulting steady tip leakage vortex from a steady flow analysis do not seem to explain measured cavitation inception correctly. The measured flow field near the tip is unsteady and measured cavitation inception is highly transient. Flow visualization with cavitation bubbles shows that the leakage vortex is oscillating significantly and many intermittent vortex ropes are present between the suction side of the blade and the tip leakage core vortex. Although the flow field is highly transient, the overall flow structure is stable and a characteristic frequency seems to exist. To capture relevant flow physics as much as possible, a Reynolds-averaged Navier-Stokes (RANS) calculation and a Large Eddy Simulation (LES) were applied for the current investigation. The present study reveals that several vortices from the tip leakage vortex system cross the tip gap of the adjacent blade periodically. Sudden changes in local pressure field inside tip gap due to these vortices create vortex ropes. The instantaneous pressure filed inside the tip gap is drastically different from that of the steady flow simulation. Unsteady flow simulation which can calculate unsteady vortex motion is necessary to calculate cavitation inception accurately even at design flow condition in such a water jet pump.
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ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels
July 8–12, 2012
Rio Grande, Puerto Rico, USA
Conference Sponsors:
- Fluids Engineering Division
ISBN:
978-0-7918-4475-5
PROCEEDINGS PAPER
Investigation of Turbulent Tip Leakage Vortex in an Axial Water Jet Pump With Large Eddy Simulation Available to Purchase
Chunill Hah
Chunill Hah
NASA Glenn Research Center, Cleveland, OH
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Chunill Hah
NASA Glenn Research Center, Cleveland, OH
Paper No:
FEDSM2012-72121, pp. 135-142; 8 pages
Published Online:
July 24, 2013
Citation
Hah, C. "Investigation of Turbulent Tip Leakage Vortex in an Axial Water Jet Pump With Large Eddy Simulation." Proceedings of the ASME 2012 Fluids Engineering Division Summer Meeting collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels. Volume 1: Symposia, Parts A and B. Rio Grande, Puerto Rico, USA. July 8–12, 2012. pp. 135-142. ASME. https://doi.org/10.1115/FEDSM2012-72121
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