CFD Investigation of Wind-powered Ships under Extreme Condition: Simulations on the NACA-0015 Foil under Deep Stall Condition
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Examensarbete för masterexamen
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This thesis is dedicated to study the loading condition of the rigid wingsails on a
ship with wind-assisted propulsion using CFD methods. OpenFOAM is used for the
CFD simulations. 2D simulation cases are performed for both low angles of attack
and 90 degrees angle of attack conditions. Simulations on a uniform 3D foil with 90
degrees angle of attack conditions are also performed.
Unsteady RANS and DES simulations are carried out to predict the loading condition
on a NACA-0015 foil. Under the conditions of low angles of attack, the k − !
SST model and the k − ! SST DDES model are used in the simulation. For 90
degrees angle of attack simulation cases, the k − ! SST model and the k − ! SST
IDDES model are used. The simulation results are compared with experimental
data. These simulation cases provide the loading condition on foils and characters
of the flow field. The possible causes of error, especially the overestimation of the
force coefficients for 90 degrees angle of attack, are discussed.
For the cases of 90 degrees angle of attack, the influence of mesh factors on the simulation
results is analyzed, which includes the refinement of profile mesh, structured
and unstructured downstream fields, and the ratio between the chord length and
the longitudinal length.
A rough prediction of the interaction between two foils is presented as well. Experiences
on performing deep stall simulation, and suggestions on wind propulsion from
an engineering perspective are also provided.
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Ämne/nyckelord
NACA-0015, IDDES, flow separation, deep stall, high Reynolds number