2.23 Hydrofoils & Propellers
Exam #2
Friday April 27, 2007
1)
[25 pts] Using linearized 2D foil theory:
a)
Find the lift coefficient of a parabolic meanline is desired to be Cl = 0.25.
Find the camber height of fo/c if the foil is to be at ideal angle of attack.
b)
What is the maximum value of
γ
(x) and where does it occur?
c)
If the cavitation number for this foil is 0.5 will this foil cavitate at the
midchord? (show your work).
2)
[15 pts] Given a 2D foil with the following characteristics:

Circulation distribution:
γ
(
x
)
U
=
0.025
1
+
cos(˜
x
)
sin(˜
x
)
⎡
⎣
⎢
⎤
⎦
⎥
+
0.007sin(˜
x
)
+
0.02sin(2˜
x
)

Elliptical thickness form with
to/c= 0.03
Find the following assuming linear foil theory: (Given x= 0 is midchord, c/2 is
the leading edge and +c/2 is trailing edge of the foil)
a)
Lift coefficient C
l
b)
u/U at the midchord upper surface (x=0)
c)
Using the Lighthill correction find q/U at the leading edge
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[40 pts] A propeller blade section at r/R=0.7 is to be designed using the NACA
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 Spring '07
 PaulD.Sclavounos
 Foil, Lift, Airfoil, lift coefficient, Propeller, Angle of attack

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