Everything Old is new again - Flettner Rotor Ship is launched

Discussion in 'Boat Design' started by rwatson, Sep 1, 2008.

  1. rwatson
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    rwatson Senior Member

  2. 1J1
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    1J1 Senior Member

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  3. 1J1
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  4. rwatson
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    rwatson Senior Member

    Wow, great video 1J1. That's the best and longest footage of Flettners in action I have ever seen.
    Well spotted.
     
  5. 1J1
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    1J1 Senior Member

    Not sure if this was posted before.
     
  6. Dolfiman
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    Dolfiman Senior Member

    Thanks, but actually it was already posted by Thiseasm , quote#7 of the thread on the rotating skin friction issue open by Rwatson : Flettner Rotors - Calculating Rotating Skin Friction https://www.boatdesign.net/threads/flettner-rotors-calculating-rotating-skin-friction.60516/

    The formulas used in this paper for the power consumption due to aerodynamical resistance to rotation for the cylinder as for the end plates involved only the rotation speed N, and not also the apparent wind U. It is valid only when there is no air flow, i.e. when U =0, cannot be used as such for the power spreadsheet of the boat in sailing condition with U.
    The power formulation of such aero resistance to rotation can be put the form of (for the cylinder) :
    Pm = Integrale of [Friction force (at the cylinder surface) * speed v (tangential speed of the cylinder surface)]
    i.e. in the form of :
    Pm = Cf * (1/2 * ρ * Sw ) * Quadratic (U, v) * v
    Sw is the "wetted" surface of the cylinder (2 pi R H)
    Quadratic (U,v) is the resulting function of the integrale, i.e. the key point where theoritical and experimental approaches can be compared.
    *** "Varvill-Norwood" exactly computes this integrale for the 2D perfect fluid assumption :
    >>> Quadratic (U,v) = 2 U^2 + v^2
    *** "Thom" proposed a formulation derived from his experiences (as far as I understood) :
    >>> Quadrativ (U,v) = k U v , k being in the range of 3 but fluctuant with U/v
    *** When U = 0, we of course have a quadratic function in just V^2, i.e. a Pm in V^3, but it is of no practical utility.

    Actually, we crucially need new first hand measurements of this power in the useful range of U/v and for various Reynolds to eventually identify a consistent quadratic function, although it is not a costly experience for any fluid mechanism lab in Universties and potentially full of interesting development on how it works.

    More details on these tentative approaches in the thread above.
     
  7. 1J1
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  8. rwatson
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    rwatson Senior Member

    Terrific article, and it looks like the class organisations are getting in on the act.
    "Norsepower says that the two units will reduce fuel consumption and associated emissions from the Pelican by about 7-10 percent. To validate the system's effectiveness in this application, Lloyd's Register's Ship Performance team will collect data during a test phase and conduct an impartial third-party assessment. "
    Norsepower-rotor-maersk-pelican-2.10977b.png

    The same Author has addressed some of the industry views on Rotors
    "Wind propulsion technologies have gained attention, offering potential fuel savings of 10-30 percent for retrofit installations and up to 50 percent for optimized newbuilds. However, Gavin Allwright, Secretary General of the International Windship Association (IWSA), says: “the same misconceptions about commercial wind propulsion solutions keep coming around, many of these are rooted in old appraisals of technologies used decades ago or on perceptions of stepping backwards, however the wave of technologies and projects coming through now are firmly focused on a modern, decarbonized fleet fit for purpose in the 21st century.” "
    Wind Propulsion Options on Show at SMM 2018 https://maritime-executive.com/features/wind-propulsion-options-on-show-at-smm-2018
     
  9. 1J1
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  10. rwatson
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    rwatson Senior Member

    This is great. A video of a four rotor cargo ship under "sail",
    MV Afros , built 2018
    Gross Tonnage: 36452
    Deadweight: 63223 t


    FlettnerSail.png

     
    Last edited: Oct 26, 2018
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  11. 1J1
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    1J1 Senior Member

    Won't the ANEMOI flickering get annoying for the crew? :D
     
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  12. rwatson
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    rwatson Senior Member

    Yeah, I bet they paint the cylinders more uniformly before long.

    Merchant ships are renowned for never doing proper lookouts anyway :)
     
  13. Mike Inman
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    Mike Inman Junior Member

    One part of the "practicality equation" that has been mentioned, but not overly emphasized, is the amount of crew-expense related to the safe operation of the system. I think this is a big part of why these rotors are appearing on the big cargo ships - they're relatively trouble-free to operate when they help, and not a big liability during normal operations. Kites and even sailing rigs can also improve fuel efficiency, but if you have to add even a single crew member to a big cargo ship in order to save that fuel, it's going to take a whole lot longer to achieve ROI - crew costs a lot more today than it did 100 years ago.
     
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  14. rwatson
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    rwatson Senior Member

    Maersk have promised to convert their fleet to zero fossil fuels by 2050.

    Maersk sets net zero co2 emission target by 2050 https://www.maersk.com/en/news/2018/12/04/maersk-sets-net-zero-co2-emission-target-by-2050


    A big part of the strategy is using wind power
    • There are now three Maersk vessels in daily commercial operation using Norsepower's rotor sails, according to its CEO.
    • "Measuring 30 meters in height and five meters in diameter, the rotor sails were installed on the product tanker in Rotterdam, Norsepower added. They will provide the vessel with "auxiliary wind propulsion" and are expected to cut fuel consumption and associated emissions by 7 to 10 percent "on typical global shipping routes." "
    Maersk Tankers has installed two huge rotor sails on one of its vessels https://www.cnbc.com/2018/08/31/maersk-tankers-installs-two-huge-rotor-sails-on-one-of-its-vessels.html
     
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