Problems working with Javafoil, stagnation point location is way off?

Discussion in 'Software' started by JamesBoatDesign, Mar 29, 2021.

Tags:
  1. JamesBoatDesign
    Joined: Mar 2021
    Posts: 2
    Likes: 0, Points: 1
    Location: Switzerland

    JamesBoatDesign New Member

    Hi everyone,

    Was hoping I could get some help with a project I'm working on with Javafoil. I would like to get the Cp distribution around my airfoils but for some reason when I run Javafoil I keep getting Cp of 1 on the upper surface and large negative values on the underside. Its almost as if the flow were being directed vertically down. I would expect the stagnation point at the leading edge but it seems to be over the whole upper surface instead. When I view the streamlines I can see the results are not very realistic. Does anyone have experience with this, is there a setting I'm missing somewhere?
     
  2. baeckmo
    Joined: Jun 2009
    Posts: 1,237
    Likes: 203, Points: 63, Legacy Rep: 1165
    Location: Sweden

    baeckmo Hydrodynamics

    That looks just ok for the kind of high-lift foil you have, but if you expect "lift" as beeing upwards, you have placed your foil upside-down. Now add more streamlines to the upper area (as drawn above); you will find the stagnation point at about the "top" point of the leading edge.
     
  3. JamesBoatDesign
    Joined: Mar 2021
    Posts: 2
    Likes: 0, Points: 1
    Location: Switzerland

    JamesBoatDesign New Member

    Thanks for your reply. Actually I would expect high downforce from this sort of setup so the orientation is correct. I'm just comparing with some CFD runs I have and I find that I have to adjust these sort of high downforce setups by up to 15 degrees to get any sort of similar Cp distribution. Wondering if others have the same experience as me.
     
Loading...
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.