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Validation of Cavitating Flows: a two-dimensional study using a NACA0012 hydrofoil
2004 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This thesis was primarily intended for investigating Fluent 6.1.18’s capability of performing cavitational computations: thickness distribution upon the suction side of a hydrofoil, the cavity downstream movement and the initiation of a so called re-entrant jet was to be studied. For validation purposes experiments have been carried through in the conventional cavitation tunnel at Rolls-Royce Hydrodynamic Research Center in Kristinehamn, Sweden. The reason for this study is due to the interest of reducing the costly time spent in the laboratory, as well as the interest of minimizing deleterious effects of cavitation. The method used when examining the cavitation was high speed film photography. With the aid of equipment delivered from Bosch-Rexroth, several test cases were set up. Two pair of test runs were arranged, where each pair had the same cavitation number but different velocities: this to observe how the dynamics of the cavity varied with the Reynolds number, as well as the effects of an increase of static pressure as a result of a velocity increment. One major drawback when simulating cavitating flows in Fluent was its incapability of solving the RANS equations for turbulence. Therefore the laminar solver had to be used when comparing with the gathered experimental data. Results show that an increase of static pressure will give a more accurate prediction. To establish a cavitating flow in Fluent, high ambient pressure has to be used. The comparison between thickness distributions from simulations and experiments were in bad agreement, it differed by as much as 100% for the more stable cases: in contrary it captured the downstream cavity edge very well. Regarding the re-entrant jet phenomenon Fluent only captured early starting jets, no late or double jets were observed during the entire thesis.

Place, publisher, year, edition, pages
2004.
Keyword [en]
Technology
Keyword [sv]
Teknik
Identifiers
URN: urn:nbn:se:ltu:diva-43716ISRN: LTU-EX--04/148--SELocal ID: 18f7bc02-723b-4d4e-9830-90b65021ed06OAI: oai:DiVA.org:ltu-43716DiVA: diva2:1016957
Subject / course
Student thesis, at least 30 credits
Educational program
Engineering Physics, master's level
Examiners
Note
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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