# ps4 - chord point(x =-c/4 3 Given a 2D foil geometry...

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2.23 Hydrofoils & Propellers Homework Assignment #4 Assigned: Monday Mar. 19, 2007 Due: Friday Apr. 6, 2007 1) A two-dimensional section has a parabolic mean line with fmax/C = 0.08 and an angle of attack α = ideal angle of attack. Assume rho = 1000 kg/m3 , Chord = 0.5m and Uo=10 m/s a) Find the Lift on the section b) Find the moment about the leading edge of the foil x/C=-0.5 ( M(x) = ρ Uo x γ (x)dx) c) Find the location of the center of Lift ( place about which moment = 0) 2) A two-dimensional section has a parabolic mean line, and is to develop a lift coefficient of Cl=0.25 at its ideal angle of attack. The foil runs at a cavitation number σ = 0.6. a) Find the camber height to achieve this lift coef. (at ideal angle of attack). b) Plot the pressure coefficient on the upper and lower surface (Plot –Cp vs x/C) . c) Find the maximum angle of attack before the foil cavitates at the quarter-

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Unformatted text preview: chord point (x = -c/4) 3) Given a 2D foil geometry defined as follows: i. f(x)/c = 0.3 (x/c) 3 – 0.12(x/c) 2 – 0.18(x/c) ii. Angle of attack = 2 degrees iii. Elliptical thickness form w/ to/c = 0.02 (note: leading edge radius for elliptical thickness is given by Rl=0.5((to/c) 2 )) Find the following assuming linear foil theory(given x=0 is midchord, -c/2 is leading edge, c/2 is the trailing edge: a) Lift Coefficient Cl b) Ideal angle of attack c) u/U on the upper surface at x=0 (midchord) d) q/U at the leading edge (using Lighthill correction) 4) Using linearized 2D foil theory for a foil with the following geometry: i. Parabolic meanline fo/c=0.07 ii. Angle of attack = 3 degrees iii. Elliptical Thickness to/c = 0.04 a). Find the Lift coefficient and the value of ϒ (x) at x/c=0.25 b) Plot CPmin vs x/C and find the location and value of Cpmin on this foil...
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## This note was uploaded on 02/27/2012 for the course MECHANICAL 2.23 taught by Professor Pauld.sclavounos during the Spring '07 term at MIT.

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ps4 - chord point(x =-c/4 3 Given a 2D foil geometry...

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