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Homework Help: Form drag of aerofoil?

  1. Oct 18, 2015 #1
    1. The problem statement, all variables and given/known data
    I have a question about a symmetrical aerofoil at zero incidence in uniform flow. I a graph Cp against (y/c), but I don't understand why it has to be against y/c. The most negative value of m is -0.69. And h=0.38 where h is ration of maximum height to chord length c. The coefficient of the profile drag Cd is 0.3
    The question asks for the value of the form drag. Can someone please help as to how to go about this question?

    2. Relevant equations
    The question says drag coefficient is given Cd=closed loop integral { Cp d(y/c)} sorry, I can't use LaTex

    3. The attempt at a solution
    First I inverted the graph, because it's just confusing this way.
    So what I did what I separated the graphs into four curves, and did line integral on each of them.
    I let u=y/c, so it's easier to integrate with respect to u.
    Curve 1: integral{ (2+2m)u/h +1 } , u from -h/2 to 0
    Curve 2: integral{ -(2+2m)u/h +1 } , u from 0 to h/2
    Curve 3: integral{ -4mu/h +m } , u from h/2 to h/(2+2m)
    Curve 4: integral{ 4mu/h +m } , u from -h/(2+2m) to -h/2

    Then I added all of them, but I didn't get the correct answer. What should I do actually?

  2. jcsd
  3. Oct 23, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
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