Jarle Kramer

PhD Candidate WP2 


Supervisor: Prof. Sverre Steen (NTNU)
Co-supervisor: Luca Savio (NTNU, SINTEF Ocean)







Kramer, Jarle Vinje. Wind propulsion. SFI Smart Maritime WEBINAR Wind-assisted propulsion; 2020-11-10

Kramer, et al. (2021). Simplified Test Program for Hydrodynamic CFD Simulations of Wind-Powered Cargo Ships.

Hydrodynamic modelling of wind-powered merchant vessels

Research topics

Most types of modern wind power devices, such as wing sails, rotor sails, and suction sails, generate thrust from the wind by creating a lift force. As a consequence, there is usually a side force from the sails which can be serval times as large as the thrust, depending on the apparent wind direction. This side force makes the ship move with a steady drift-, rudder- and heel-angle which could both increase the resistance of the vessel, and potentially pose a safety risk.
The goal of my research is to figure out how important these negative effects from wind power is for typical cargo ships. When problems are discovered, the goal is to find ways to reduce them to a minimum by either suggesting design alterations or new control principles. Different modelling approaches are investigated with the goal of making numerical tools that are usable in a design loop for wind-powered vessels.

Industrial goal

  • Generate efficient numerical tools for evaluating both the hydrodynamics and the aerodynamics of a wind-powered merchant vessel during a design loop.
  • Detect and quantify potential problems with wind-power devices for typical cargo ships.
  • Suggest solutions to problems and figure out how merchant vessels can extract large amounts of power from the wind in order to reach future greenhouse gas reduction goals.

Scientific questions

  • How important are the hydrodynamic effects due to the side force of a sail? 
  • How can we model the negative hydrodynamic effects due to wind power accurately and efficiently?
  • What can we do to minimize the negative hydrodynamic effects? 
  • Which design alterations are necessary for vessels where a large amount of the power comes from the wind?



Main achievements 2020


  • Implementation of sails models in a route simulation framework using both a discrete lifting line method and a Vortex Lattice Method. The methods are necessary for modelling wing-to-wing interaction which are seen to strongly affect both the thrust and the side force from sails.
  • The MMG manoeuvring model was implemented in a route simulation framework, with slight modifications to the rudder model in order to improve the accuracy. Test procedures and algorithms for tuning the model with CFD data was made.
    The route simulation model along with the tuning procedure was validated by executing a large set of validation experiments using CFD.