Tandem hydrofoil assisted catamaran upwash/downwash calculation?

Discussion in 'Hydrodynamics and Aerodynamics' started by S V, Aug 5, 2021.

  1. S V
    Joined: Jan 2019
    Posts: 78
    Likes: 5, Points: 8
    Location: Lithuania

    S V Junior Member

    Hello,

    Design object is power hydrofoil assisted catamaran with tandem foil system. The foils are full length between the amas at keel depth or 1-2cm above it just for practical reasons. The shape of both foils is like HYSUCAT front foil.
    I was searching on the net some info about tandem foils interaction, and found this empirical dependence:

    L=1.95*V*sqrt(B/g)

    L - length of wave hollow behind bow foil, m
    V - speed, m/s
    B - immersed span of bow foil, m
    g - gravitational constant m/ss

    As it turns out most of the successfull tandem hydrofoils of soviet and Rodriguez design were using this intentionaly or not to their advantage: the stern foil is at the upwash of the stream from front foil at cruise speed. And the most efficient designs have ~0.7-0.8L distance between the foils where the upwash is most beneficial, even if that epirical dependence was discovered about 30+ years later...

    The questions of mine are:
    1. This dependence seem to be very very simple. No dependence on the attack angle, sweep or chord of the front foil. Are there other formulas known?
    2. Design specific interaction - how side amas which act as a big long endplate may change the wave hollow length?

    Prof. Migeotte seem not to be on this forum anymore, but input from other hydrofoil gurus is very welcome.

    Thank you.
     
    Last edited: Aug 5, 2021
Loading...
Similar Threads
  1. Eytan Levi
    Replies:
    0
    Views:
    1,105
  2. container
    Replies:
    7
    Views:
    3,118
  3. vejas
    Replies:
    34
    Views:
    8,881
  4. revintage
    Replies:
    8
    Views:
    2,005
  5. revintage
    Replies:
    14
    Views:
    13,523
  6. rallyhybrid
    Replies:
    39
    Views:
    4,983
  7. optiwings
    Replies:
    1
    Views:
    1,910
  8. Tommifin
    Replies:
    5
    Views:
    2,298
  9. Ittiandro
    Replies:
    2
    Views:
    5,507
  10. bjn
    Replies:
    23
    Views:
    6,179
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.