CFD investigation of wind powered ships under extreme conditions
Typ
Examensarbete för masterexamen
Program
Naval architecture and ocean engineering (MPNAV), MSc
Publicerad
2021
Författare
Blount, Henry
Portell Lasfuentes, Jose Maria
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
With the International Maritime Organization’s (IMO) goal of reducing greenhouse
gas emissions 50% by 2050, the design and propulsion of ships must change rapidly.
The use of wind propulsion is one solution. A CFD analysis has been performed using
the sail geometry of the Oceanbird Ro-Ro ship, with the purpose of determining
the forces on the sails.
Star-CCM+ has been used to analyze the NACA 0015 wing profile in both 2D and
3D. In 2D, the k − ! SST model has been employed to compare the lift and drag
coefficients with wind tunnel data and to show the effects of dynamic stall. In 3D,
the IDDES model has been used to compute the lift and drag coefficients with 3D
effects and to determine the interaction effects between multiple wings
CFD results show that lift and drag forces slightly differ from the forces seen in
previous wind tunnel experiments. The physical time plays an important role in the
simulations, both in the 2D and 3D situations, what has led to different conclusions,
mainly in relation to the setup of the mesh and physics of the investigation. Dynamic
stall affects the performance of the wing when rotating from one angle of attack to
another, being the biggest determinant the rotational speed. Both the integrity of
the structure and the thrust production need to be considered when establishing the
dynamic stall situation. In the multiple wing simulations, the rear wing has shown
to be severely affected by the leading wing during stalled conditions. Finally, the
frequencies of vibrations from vortex shedding have been calculated which are interesting
for the structural integrity of the rig, concluding that the stalled situations
should be avoided since the shedding frequencies could compromise the structure.
Suggestions for further work include wind tunnel tests to confirm the data in this
report and a more in-depth structural analysis.
Beskrivning
Ämne/nyckelord
CFD , Oceanbird , Naval Architecture , NACA0015 , Windship , Sailing , Shipping , Climate Change