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Unformatted text preview: 'I':r*“'“"‘“""3‘ “EEK s . ia'v'iiul n: g! 11E 311113 Spring 1996 Jill
Final Exam, Part I Closed Book and notes Answer each question concisely {in the space provided, if possible]. Make graphical
sketches where they seem useful to illustrate your point. He clear and unambiguous.
Except 1where noted otherwise, each question is worth 1 point in the ﬁnal grade. Turn
in this part in approximately an hour, after which you can begin to work on Part II. 1. What does the quantity If pl? ﬁ' do represent physically, and why does the dot
product appear it'tsicle'iII cs Mrs55 Haul Fol? J. '4'? [S ‘2. 'What is the difference between absolute pressure and gage pressure? 3. Explain the principles involved in the determination of drag ofa twodimensional
hody from measurements of the velocity proﬁles in front and behind {in the wake 0f} the body. "J—
(a ll 55’ r' Lo?" up} if} i: ﬂitHm!“ t' WA 4. Suppose in a two‘dimensionnl ﬂow the velocity components u and s are given.
How would you use this information to obtain the equations representing stream lines in the coordinate plane?
Cl)“ is J.
_." W M 5. 1What is an irrotational vortex? What is special about the ﬂow at its core?
(Sniff; 54'1““in "4 _":ftrf_ ._., _l"'l.r .2 (on: refra't . i .4 5W”? “iii1“? "
WW” * + w n
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I/Wltﬂr I f r“ ti. State at! the necessary conditions for Bernoulli equation to to apply hoth along
and across streamlines nooﬂW5ﬂ:k $3717 at? {4/ I
1 if. can 5% 5 “53W%}
{ﬁtsEEC? Errote‘ffﬂ’l" If! it'ﬁfcrdy “£27155, 1" . ﬁts discussed in class, in two—dimensional potential ﬂow both the stream function
and the velocity potential satisfy Laplseeequation1 which is linear. What is the
importance of this fact? [What has it allowed us to do?) ﬁﬁj sﬁuﬂe ﬂeas
_. f 
7?) a 94%” 3 idrw'i",w i ”mi/5 3. Hour do you deﬁne the strength of a source? Include information on its proper
dimensions. L .1 whose 776““ :— in;
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scat *1 9. As discussed in class.‘ the case of uniform ﬂow plus a source can represent ﬂow
over a sloping hill. How would you adjust the uniform ﬂow andfor source
parameters in order to represent a higher hill? .31; If} {jg—lass?!" giiirfﬂ It]. In potential ﬂour over a cylinder the theory predicts the same pressure distri
butions in front and ”behind the cylinder. In what sense does this result violate reality?
fri‘f’i'iﬂh (WW€5
fq “if": {JP{'5 “7' Trait/f"?
2 (mushi ( I'.IHr 4L blei of 1]. Explain brieﬂy why airplanEs can ﬂy. 12. If the vortex strength distribution along the chord line of an airfoil [from leading
edge to trailing edge} is known, state two lreyr steps you would use to obtain the lift force per unit span. If
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Jﬂl *2;ka I} l ff/ a“: J
r” L5 13. What is the center of pressure? Where is it located for a. symmetric airfoil?
.— Lvd'ﬂrf LEE1+ Gr (+9.
g 1.4 .r'lLU'" Rufﬂei "41/ or.— 14. Explain how a. trailing 1Hotter: forms for a wing of ﬁnite span. Fists» [frkfmj rem" ﬁ'uf‘d two/3%
15. Explain why there is a negative downwash tlrelnrusitfp+ between the root and tips all EI ﬁnite win;
lﬂ_67lLtCF0( Df/ﬂpgifr/dﬁ‘ﬁl it;
If“! Olﬂi'ré'hj Vgﬁf‘l'i‘MJ 15. For what type of wing are the angles n, or and aha all independent of spanwise
locations across the wing? Lint 5N] 1?. (2 pts] Explain how induced dragarises, anti state two ways to minimize it [far a given lift] in wing design. (Jim: 7%? Wﬁﬂﬂ
MFIMrﬂH“ ﬂjng/J 13. [2 pta] Make a carequ sketch that compares the variation of lift weﬁicient versus
geometric angle 91' attack for {i} a symmetric airfoil [ii] a cambered airfnii and [iii] an unturiste‘d elliptic wing. ...
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 Spring '08
 Yeung

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