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Fluegelopti.
User deleted
Hello,
I ve tried the inverse airfoil design routine Qdes, however I cannot figure out the meaning of the plot which shows up, when entering that mode. As far as i know, on the horizontal axis the arc lenght of the airfoil is beeing displayed, with the leading edge beeing roughly in the center of the plot. However on the vertical axis the unit q/v_0 does not make much sense to me. If it is the speed distribution why does it have negative Values? Would someone mind explaining it?
Regards
Benjamin. -
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Consider the velocity from the point of view of an ant that starts crawling along the upper surface from the trailing edge. The wind is blowing in the ant's face, making it positive. But as the ant passes the stagnation point and proceeds toward the trailing edge on the lower surface, the ant feels the wind blowing from its tail. That is a negative wind. Traversing the graph from right to left shows what the ant would experience.
I don't think the X axis is actually the arc length. I believe it is the projection onto the X axis. Admittedly that is a fine distinction because most airfoils are fairly thin. But it does make things quite sensitive near the leading edge.
The vertical axis is the velocity ratio - local velocity divided by the freestream speed..
