RANS analyses of cavitating propeller flows: Dissertation

    Research output: ThesisDissertationMonograph

    Abstract

    This publication presents validation studies for the cavitation model implemented in the Reynolds-averaged Navier-Stokes equation solver FINFLO. The validation studies relate to ship propellers in uniform and non-uniform inflow conditions. The main physical phenomena involved in cavitation are first introduced. Then, the cavitation phenomena related to marine applications are presented, and the physics behind sheet and vortex cavitation are explained. As cavitating flows are strongly related to turbu-lence, the physics behind turbulence and its simulation methods are also introduced. The benefits and uncertainties related to cavitation tests are described. It is important to understand the drawbacks of experimental methods when comparing the simulation results with the test observations. A brief description of the existing cavitation models is also given, and the utilized cavitation model and its numerical implementation are described in detail. The validation cases are introduced and the simulation results are compared to the out-come of the cavitation tests. The simulation results generally showed good correlation with the experiments. Sheet cavitation was observed in the tests on both the suction and pressure sides of the blades in the validation cases, which was also found in the simulations. The cavitating tip vortices were also found to be similar in the experiments and simulations. The propeller slipstream must be discretized with a high resolution grid in order to predict the cavitating tip vortices and the wakes of the blades with reasonable accuracy. A verification and validation analysis was performed for the global propeller performance characteristics according to the methodology recommended by the ITTC. The influence of the empirical constants in the utilized mass transfer model on the cavitating tip vortices is studied. Finally, explanations for the similarities and differences between the results of the ex-periments and the simulations are discussed. The main differences are found to be caused by laminar flow separation at the leading edge of the blades in the tests, and the limitations of the turbulence and cavitation models utilized in the present simulations.
    Original languageEnglish
    QualificationDoctor Degree
    Awarding Institution
    • Aalto University
    Supervisors/Advisors
    • Matusiak, Jerzy, Supervisor, External person
    Award date10 Sep 2012
    Place of PublicationEspoo
    Publisher
    Print ISBNs978-951-38-7946-4
    Electronic ISBNs978-951-38-7947-1
    Publication statusPublished - 2012
    MoE publication typeG4 Doctoral dissertation (monograph)

    Fingerprint

    propellers
    cavitation flow
    simulation
    blades
    vortices
    propeller slipstreams
    flow separation
    physics
    turbulence models
    suction
    leading edges
    laminar flow
    wakes
    Navier-Stokes equation
    mass transfer
    turbulence
    grids
    methodology

    Keywords

    • cavitation
    • CFD
    • hydrodynamics
    • propeller
    • RANS
    • simulation
    • tip vortex
    • turbulence

    Cite this

    Sipilä, T. (2012). RANS analyses of cavitating propeller flows: Dissertation. Espoo: VTT Technical Research Centre of Finland.
    Sipilä, Tuomas. / RANS analyses of cavitating propeller flows : Dissertation. Espoo : VTT Technical Research Centre of Finland, 2012. 144 p.
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    title = "RANS analyses of cavitating propeller flows: Dissertation",
    abstract = "This publication presents validation studies for the cavitation model implemented in the Reynolds-averaged Navier-Stokes equation solver FINFLO. The validation studies relate to ship propellers in uniform and non-uniform inflow conditions. The main physical phenomena involved in cavitation are first introduced. Then, the cavitation phenomena related to marine applications are presented, and the physics behind sheet and vortex cavitation are explained. As cavitating flows are strongly related to turbu-lence, the physics behind turbulence and its simulation methods are also introduced. The benefits and uncertainties related to cavitation tests are described. It is important to understand the drawbacks of experimental methods when comparing the simulation results with the test observations. A brief description of the existing cavitation models is also given, and the utilized cavitation model and its numerical implementation are described in detail. The validation cases are introduced and the simulation results are compared to the out-come of the cavitation tests. The simulation results generally showed good correlation with the experiments. Sheet cavitation was observed in the tests on both the suction and pressure sides of the blades in the validation cases, which was also found in the simulations. The cavitating tip vortices were also found to be similar in the experiments and simulations. The propeller slipstream must be discretized with a high resolution grid in order to predict the cavitating tip vortices and the wakes of the blades with reasonable accuracy. A verification and validation analysis was performed for the global propeller performance characteristics according to the methodology recommended by the ITTC. The influence of the empirical constants in the utilized mass transfer model on the cavitating tip vortices is studied. Finally, explanations for the similarities and differences between the results of the ex-periments and the simulations are discussed. The main differences are found to be caused by laminar flow separation at the leading edge of the blades in the tests, and the limitations of the turbulence and cavitation models utilized in the present simulations.",
    keywords = "cavitation, CFD, hydrodynamics, propeller, RANS, simulation, tip vortex, turbulence",
    author = "Tuomas Sipil{\"a}",
    year = "2012",
    language = "English",
    isbn = "978-951-38-7946-4",
    series = "VTT Science",
    publisher = "VTT Technical Research Centre of Finland",
    number = "22",
    address = "Finland",
    school = "Aalto University",

    }

    Sipilä, T 2012, 'RANS analyses of cavitating propeller flows: Dissertation', Doctor Degree, Aalto University, Espoo.

    RANS analyses of cavitating propeller flows : Dissertation. / Sipilä, Tuomas.

    Espoo : VTT Technical Research Centre of Finland, 2012. 144 p.

    Research output: ThesisDissertationMonograph

    TY - THES

    T1 - RANS analyses of cavitating propeller flows

    T2 - Dissertation

    AU - Sipilä, Tuomas

    PY - 2012

    Y1 - 2012

    N2 - This publication presents validation studies for the cavitation model implemented in the Reynolds-averaged Navier-Stokes equation solver FINFLO. The validation studies relate to ship propellers in uniform and non-uniform inflow conditions. The main physical phenomena involved in cavitation are first introduced. Then, the cavitation phenomena related to marine applications are presented, and the physics behind sheet and vortex cavitation are explained. As cavitating flows are strongly related to turbu-lence, the physics behind turbulence and its simulation methods are also introduced. The benefits and uncertainties related to cavitation tests are described. It is important to understand the drawbacks of experimental methods when comparing the simulation results with the test observations. A brief description of the existing cavitation models is also given, and the utilized cavitation model and its numerical implementation are described in detail. The validation cases are introduced and the simulation results are compared to the out-come of the cavitation tests. The simulation results generally showed good correlation with the experiments. Sheet cavitation was observed in the tests on both the suction and pressure sides of the blades in the validation cases, which was also found in the simulations. The cavitating tip vortices were also found to be similar in the experiments and simulations. The propeller slipstream must be discretized with a high resolution grid in order to predict the cavitating tip vortices and the wakes of the blades with reasonable accuracy. A verification and validation analysis was performed for the global propeller performance characteristics according to the methodology recommended by the ITTC. The influence of the empirical constants in the utilized mass transfer model on the cavitating tip vortices is studied. Finally, explanations for the similarities and differences between the results of the ex-periments and the simulations are discussed. The main differences are found to be caused by laminar flow separation at the leading edge of the blades in the tests, and the limitations of the turbulence and cavitation models utilized in the present simulations.

    AB - This publication presents validation studies for the cavitation model implemented in the Reynolds-averaged Navier-Stokes equation solver FINFLO. The validation studies relate to ship propellers in uniform and non-uniform inflow conditions. The main physical phenomena involved in cavitation are first introduced. Then, the cavitation phenomena related to marine applications are presented, and the physics behind sheet and vortex cavitation are explained. As cavitating flows are strongly related to turbu-lence, the physics behind turbulence and its simulation methods are also introduced. The benefits and uncertainties related to cavitation tests are described. It is important to understand the drawbacks of experimental methods when comparing the simulation results with the test observations. A brief description of the existing cavitation models is also given, and the utilized cavitation model and its numerical implementation are described in detail. The validation cases are introduced and the simulation results are compared to the out-come of the cavitation tests. The simulation results generally showed good correlation with the experiments. Sheet cavitation was observed in the tests on both the suction and pressure sides of the blades in the validation cases, which was also found in the simulations. The cavitating tip vortices were also found to be similar in the experiments and simulations. The propeller slipstream must be discretized with a high resolution grid in order to predict the cavitating tip vortices and the wakes of the blades with reasonable accuracy. A verification and validation analysis was performed for the global propeller performance characteristics according to the methodology recommended by the ITTC. The influence of the empirical constants in the utilized mass transfer model on the cavitating tip vortices is studied. Finally, explanations for the similarities and differences between the results of the ex-periments and the simulations are discussed. The main differences are found to be caused by laminar flow separation at the leading edge of the blades in the tests, and the limitations of the turbulence and cavitation models utilized in the present simulations.

    KW - cavitation

    KW - CFD

    KW - hydrodynamics

    KW - propeller

    KW - RANS

    KW - simulation

    KW - tip vortex

    KW - turbulence

    M3 - Dissertation

    SN - 978-951-38-7946-4

    T3 - VTT Science

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -

    Sipilä T. RANS analyses of cavitating propeller flows: Dissertation. Espoo: VTT Technical Research Centre of Finland, 2012. 144 p.