ARUNAI ENGINEERIN COLLEGE THIRUVANNAMALAI
AE6412
AERODYNAMICS AERODYNAMIC S LABORATORY LABORATORY
LAB MANUAL
For 4rd semester B.E/B.Tech students
Department o Aerona!t"#a$ Aerona!t"#a$ En%"neer"n%
LIST O& E'UI(MENTS
(for a batch of 30 students)
SI)N O
RE'UIRMENT
'UANTITY
1
Venturimeter
1 each
2
Orificemeter
1 set
3
Pipe friction apparatus
1 No .
Susonic !ind tunne"
1 each
#
$erofoi" %ode"& rou'h
1 each
(
$erofoi" %ode"& smooth
1 No .
)
$erofoi" %ode"& c*"inder
1 No .
+
$erofoi" %ode"& f"at p"ate
1 No .
4
UNIVERSITY (RACTICAL E*AMINATION
ALLOTMENT O& MAR+S
,nterna" $ssessment
- 2 mars
Practica" E0amination
- ) mars
INTERNAL ASSESSMENT,2- Mar./0
Staff shou"d maintain the assessment e'ister and the ead of the epartment shou"d monitorit. S(LIT U( O& INTERNAL MAR+S
ecord Note
1 mars
%ode" E0am
mars
$ttendance
mars
Tota$
2- mar./
UNIVERSITY E*AMINATION
The e0amination 5i"" e conducted for 1 mars. Then the mars 5i"" e ca"cu"ated to ) mars. ALLOCATION O& MAR+S
$im and Procedure
3 mars
%ode"in'
3 mars
Simu"ation
2 mars
esu"t
1 mars
Vi6a Voce
1 mars
Tota$
1-- mar./
LIST O& E*(ERIMENTS AS (ER SYLLABUS
1. $pp"ication of Bernou""i7s E8uation E8uation 9 6enturimeter and orifice meter. 2. Frictiona" "oss in "aminar f"o5 throu'h pipes. 3. Frictiona" "oss in turu"ent f"o5 throu'h pipes. 4. :a"iration of a susonic !ind tunne". . etermination of "ift for the 'i6en airfoi" section. #. Pressure distriution o6er a smooth circu"ar c*"inder. (. Pressure distriution o6er a rou'h circu"ar c*"inder. ). Pressure distriution o6er a s*mmetric aerofoi". +. Pressure distriution o6er a camered aerofoi". 1. F"o5 6isua"i;ation studies in susonic f"o5s. Tota$ 4 (ERIODS
TABLE O& CONTENTS
E*CERSISE NO)
TITLE LIST O& NOMENCLATURES
1 2 3 4 # ( ) 1
$pp"ication of Bernou""i7s E8uation 9 6enturimeter and orifice meter. Frictiona" "oss in "aminar f"o5 throu'h pipes. Frictiona" "oss in turu"ent f"o5 throu'h pipes. :a"iration of a susonic !ind !ind tunne". etermination of "ift for the 'i6en airfoi" section. Pressure distriution o6er a smooth circu"ar c*"inder. Pressure distriution o6er a rou'h circu"ar c*"inder.). Pressure distriution o6er a s*mmetric aerofoi". Pressure distriution o6er a camered aerofoi". F"o5 6isua"i;ation studies in susonic f"o5s.
(AGE NO)
LIST O& NOMENCLATURES
SI)N O)
SYMBO L
1
: p
Pressure coefficient
V
Free stream 6e"ocit* of the f"uid
PT
Tota" pressure
PS
Static pressure
8
*namic pressure
#
(
<5ater
)
'
$cce"eration due to 'ra6it* is +.)1 m / s 2
+
:@
:oefficient of "ift force
1
:
:oefficient of dra' force
11
:S
:oefficient of side force
12
FT
Theoretica" force
13
F@
@ift force
14
F
ra' force
1
FS
Side force
1#
S
Surface $rea =S ? - Span =? A :hord =:?
1(
$n'"e of attac
2 3 4
DESCRI(TION
Free stream f"uid densit* =$ir at sea "e6e" and 1 >:? is 1.22 ' / m3 !ater !a ter densit* is 1 ' / m 3
A((LICATION O& BERNOULLIS E'UATION 5 VENTURIMETER AND ORI&ICEMETER)
E3) No) -1
Date
A"m
To understand understand the concept in 'eneration Bernou""i7s E8uation 9 6enturimeter and orifice meter .
Apparat!/ Re!"re7
6enturimeter and orifice meter ifferentia" C&tue :o""ectin' tan Stop 5atch
&ORMULAE
1. ACTUAL DISCHARGE D 3
act - $ 0 h / t =m / s? 2. THEORTICAL DISCHARGE D th - a 1 0 a 2 0 2 ' h /
a 1
2
9 a 2
2
3
=m / s?
!hereD $
- $rea of co""ectin' co""ectin' tan in m
2
h - ei'ht of co""ected 5ater in tan - 1 cm a 1 - $rea of in"et pipe in
m2
a 2 - $rea of the throat in
m
' t
- Sp Specif* 'ra6it* in
2 2
m/s
- Tim Timee tae taen n for for h cm rise rise of of 5ate 5ater r
- Orifi Orifice ce head head in term termss of f"o5 f"o5in' in' "i8u "i8uid id =1 G 2? =s m / s 1 & 1? !hereD 1 - %anometric head in first "im 2 - %anometric head in second "im s m - Specific 'ra6it* of %anometric "i8uid
s1 - Specific 'ra6it* of f"o5in' "i8uid 5ater - 1 Manometric reading !"o
Diameter in mm
H1 cm of Hg
H2 cm of Hg
Manometric head H=(H1~H2) $ 12! $ 1%
&2
Time taken for „h cm cm rise of ‟
#ater „t ec ec ‟ ‟
Actual discharge &' Q act $ 1% m ' ) s
Mean *d =
Theoreti discharge &' $ 1% m ' ) s
<) CO E&&ICENT O& DISCHARGE
:o& efficient of dischar'e - act / th
=no units?
DESCRI(TION
Orifice meter has t5o sections. First one is of area a 1 and second one of area a2 it does not ha6e throat "ie 6enturimeter 6enturimeter ut a sma"" ho"es on a p"ate fi0ed a"on' the diameter of pipe. The mercur* "e6e" shou"d not f"uctuate ecause it 5ou"d come out of manometer.
(ROCEDURE
1. The pipe pipe is is se"ecte se"ected d for for doin' doin' e0pe e0perim riment entss 2. The moto motorr is s5itch s5itched ed on on as a resu"t resu"t 5ater 5ater 5i"" 5i"" f"o5 f"o5 3. $cco $ccord rdin in' ' to the f"o5 f"o5 the the merc mercur* ur* "e6e" "e6e" f"uctu f"uctuat ates es in the the C&tu C&tuee manometer 4. The The rea readi din' n' of 1 and 2 are noted . The time time taen taen for 1 cm rise rise of 5ater in the co""ecti co""ectin' n' tan tan is noted noted #. The e0perim e0periment ent is repeated repeated for for 6arious 6arious f"o5 f"o5 in in the same pipe pipe (. The co&ef co&effic ficien ientt of discha dischar' r'ee is ca"cu"a ca"cu"ated ted
RESULT The co efficient of dischar'e throu'h Venturimeter Venturimeter and Orificemeter is HHH =No unit?
&RICTIONAL LOSS IN LAMINAR &LO= THROUGH (I(ES)
E3) No) -2
Date
A"m
To find the frictiona" "oss in "aminar f"o5 f"o5 throu'h pipes. Apparat!/ Re!"re7
$ pipe pro6ided 5ith in"et and out"et and pressure tappin' ifferentia" u&tue manometer :o""ectin' tan 5ith pie;ometer Stop5atch Sca"e
&ORMULAE 1) &RICTION &RICTION &AC &ACTOR TOR 8 & 9
f-20'0d0h
f
2
/ " 0 6 =no unit?
!here 2
' - $cce"eration due to 'ra6it*
=m / sec ?
d - iameter of the pipe
=m?
" - @en'th of the pipe
=m?
6 - Ve"ocit* of "i8 "i8u uid fo""o5in' in the pipe
=m / s? s?
hf - @oss of head due to friction
=m?
- h1 G h2 !here h1 - %anometric head in the first "ims h2 - %anometric head in the second "ims 2) ACTUAL ACTUAL DISCHARG DISCHARGE E
-$0h/t
3
=m / sec?
!here $ - $rea of the co""ectin' tan
2
=m ?
h - ise of 5ater for cm
=m?
t - Time taen for cm rise
=sec?
Manometer readings
Time for +cm
Actual discharge
,elocit-
Diameter of !"o
.i.e mm
rise of h1 $
1%
&2
h2 $ &2
1%
h f = = (h1&h2) &2
#ater t sec
, '
m s
$ 1%
Mean f =
m)s
<) VELOCITY
V - / a =m / sec sec?? !here 3
- $ctua" dischar'e
=m / sec?
$ - $rea of the pipe
=m2?
DESCRI(TION
!hen "i8uid f"o5s throu'h a pipe"ine it is suIected to frictiona" resistance. The frictiona" resistance resistance depends upon the rou'hness rou'hness of the pipe. %ore the rou'hness rou'hness of the pipe 5i"" e more the frictiona" resistance. The "oss of head et5een se"ected "en'ths of the pipe is oser6ed.
(ROCEDURE
1. The diameter diameter of the pipe pipe is measur measured ed and the interna interna"" dimensio dimensions ns of the co""ectin co""ectin' ' tan and the "en'th of the pipe "ine is measured 2. Jeepin' Jeepin' the out"et out"et 6a"6e 6a"6e c"osed c"osed and and the in"et 6a"6e opened opened 3. The out"e out"ett 6a"6e 6a"6e is s"i'ht"* s"i'ht"* opene opened d and the manom manometer eter head head on the the "ims "ims h 1 and h 2 are noted 4. The The ao6 ao6ee proc proced edur uree is repe repeat ated ed * 'radua 'radua""* ""* incre increasi asin' n' the f"o5 f"o5 rate rate and and then then the correspondin' readin's are noted.
Re/!$t RESULT
0 1
&2
=no unit?
1.
The frictiona" factor Kf K for 'i6en pipe -
2.
The friction factor for 'i6en pipe * 'raphica" method - HH 0 1 = no unit ?
&2
E3)No -<
&RICTIONAL LOSS IN TURBULENT &LO= THROUGH (I(ES)
DATE
A"m
To find the frictiona" "oss in turbulent flow through pipes. Apparat!/ Re!"re7
$ pipe pro6ided 5ith in"et and out"et and pressure tappin' ifferentia" u&tue manometer :o""ectin' tan 5ith pie;ometer Stop5atch Sca"e
&ORMULAE 1) &RICTION &RICTION &AC &ACTOR TOR 8 & 9
f-20'0d0h
f
2
/ " 0 6 =no unit?
!here 2
' - $cce"eration due to 'ra6it*
=m / sec ?
d - iameter of the pipe
=m?
" - @en'th of the pipe
=m?
6 - Ve"ocit* of "i8 "i8u uid fo""o5in' in the pipe
=m / s? s?
hf - @oss of head due to friction
=m?
- h1 G h2 !here h1 - %anometric head in the first "ims h2 - %anometric head in the second "ims 2) ACTUAL ACTUAL DISCHARG DISCHARGE E
-$0h/t
3
=m / sec?
!here $ - $rea of the co""ectin' tan
2
=m ?
h - ise of 5ater for cm
=m?
t - Time taen for cm rise
=sec?
Manometer readings
Time for +cm
Actual discharge
,elocit-
Diameter of !"o
.i.e mm
rise of h1 $
1%
&2
h2 $ &2
1%
h f = = (h1&h2) &2
#ater t sec
, '
m s
$ 1%
Mean f =
m)s
16
<) VELOCITY
V - / a =m / sec sec?? !here 3
- $ctua" dischar'e
=m / sec?
$ - $rea of the pipe
=m2?
DESCRI(TION
!hen "i8uid f"o5s throu'h a pipe"ine pipe"ine it is suIected suIected to frictiona" frictiona" resistance. resistance. The frictiona" frictiona" resistance depends upon the rou'hness of the pipe. %ore the rou'hness of the pipe 5i"" e more the frictiona" resistance. The "oss of head et5een se"ected "en'ths of the pipe is oser6ed.
(ROCEDURE
1. The diameter diameter of the pipe pipe is measured measured and the the interna" interna" dimensio dimensions ns of the co""ecti co""ectin' n' tan and and the "en'th of the pipe "ine is measured 2. Jeepin' Jeepin' the the out"et out"et 6a"6e 6a"6e c"osed c"osed and and the in"et 6a"6e 6a"6e opened opened 3. The out"et out"et 6a"6e 6a"6e is s"i'h s"i'ht"* t"* opened opened and and the manomet manometer er head on on the "ims "ims h 1 and h2 are noted 4. The ao6e ao6e procedure procedure is repeated repeated * 'radua""* 'radua""* increasi increasin' n' the f"o5 rate rate and then the correspo correspondin ndin' ' readin's are noted.
RESULT &2
0 1
=no unit?
1.
The frictiona" factor Kf K for 'i6en 'i6en pipe -HH.
2.
The friction factor for 'i6en pipe * 'raphica" method - HH 0 1 = no unit ?
&2
17
CALIBRATION O& A SUBSONIC =IND TUNNEL)
E3)No -4 Date
A"m
To find the 6e"ocit* at attest section in a susonic 5ind tunne" and to p"ot the 'raph for rpm is test section 6e"ocit*.
Apparat!/ Re!"re7
Susonic !ind Tunne" %u"timeter Sca"e Pitot static tue Pitot tue
&orm!$a U/e7
V =
√
2 glwah
la
m>/
=?ere@ % a##e$erat"on 7!e to %ra"t: $ 7en/"t: o ater $! 7en/"t: o a"r e$o#"t: o te/t /e#t"on H
pre//!re ?ea7
(ro#e7!re
1? The static static and d*namic d*namic pressure pressure 6aries 6aries at different different 6e"ocit* 6e"ocit* due to inetic inetic ener'* ener'* chan'e chan'e in the 5ind tunne" 2? But the the tota" pressu pressure re in the the 5ind tunne tunne"" remains remains the sectio section. n. 3? $fter tain' tain' the 6a"ues 6a"ues ca"cu"a ca"cu"ate te the the 6e"ocit* 6e"ocit* * usin' usin'
∆ h and same constant.
4? From the ta"e ta"e it seen that that for 6ar*in' 6ar*in' P% sand static static pressure pressure the tota" tota" pressure pressure remains remains the same ? Fina""* Fina""* p"ot p"ot the the 'raph 'raph et5ee et5een n P% and 6e"oci 6e"ocit* t*..
18
Ta!$at"on
S.No
Speed
Static pressure
Tota" Pressure
=
rpm
hs=mm?
ho=mm?
× 10 ¿
Grap?
Plot for RPM vs. Test Test section section Vel Velocity ocity
Re/!$t
Thus the p"ot for P% 6s. Test section Ve"ocit* has een dra5n.
−3
Ve"ocit* m/s
19
DETERMINATION DETERMINATION O& LI&T AND DRAG &OR THE GIVEN AIR&OIL SECTION)
E3) No) -
Date
A"m
To determine the coefficient of "ift and dra' usin' section t*pe 5ind tunne" for the 'i6en aerofoi" section.
Apparat!/ Re!"re7
Susonic !ind Tunne" %u"timanometer $n'"e sca"e $erofoi" section &orm!$a U/e7
1? :oef :oeffi fici cien entt of pres pressu sure re
c p=
pl− P 1 2
∞
l∞ v ∞
!here
pl &@oad pressure at point in m of 5ater p∞ &$mient pressure in m of 5ater la &ensit* of air '/ m2 v ∞ &Ve"ocit* of 5ind in 5ind tunne" m/s 2? Ve"ocit* "ocit* of of 5ind 5ind tunne" tunne" for 'i6en 'i6en rpm
V = !here
√
2 glwah
la
'& acce"eration due to 'ra6it* "5& densit* of 5ater "u& densit* densit* of air air 6&6e"ocit* of test section &
pressure head
3? :oefficien :oefficientt of norma" norma" force force and and a0ia" a0ia" force
m/s
20
CN =
CA=
1
c 1
c
∫ ( cp l−cp u ) dx
∫ ( cpu− cpl ) dx
!here
cpl -:oefficient of pressure at "o5er chamer cpu -:oefficient of pressure at upper chamer 4? :oeffic :oefficient ient of of "ift=@? "ift=@? and and coeffic coefficient ient of of ra'=? ra'=?
c L =c N cos ∝−c A sin ∝ c D =c N sin ∝ + cos ∝ !here ∝
angle of =angle
attack attack
? To dete determ rmine ine the the "if "iftt and and dra' dra' 1
L=c L × la v ∞
2
2
D= c P ×
1 2
la v ∞
2
=N?
=N?
v c p=1 − v∞
2
Upper /"7e
S.No
Loer /"7e S.No
0/c
*/c
p L
∆ h in m of H 2 O
c p u
0/c
*/c
p L
∆ h in m of H 2 O
c p l
21
S)No
c p l
c p u norma$
c p u a3"a$
c p l normal normal
ProcedureD 1? 2? 3? 4? ? #?
!ind !ind tunne" tunne" is chece checed d for its 5ori 5orin' n' initia" initia""* "*.. The 'i6en 'i6en aerofoi" aerofoi" is is fi0ed in the test section at an'"e an'"e of attac to chord "ine. !ind !ind tunne tunne"" is turned turned on on is fi0ed fi0ed at re8 speed speed The stat static ic and tota" tota" pressur pressuree is first first measu measured. red. Csin' attained attained mu"timanometer mu"timanometer the pressure pressure of a rise aerofoi" aerofoi" for for 12 sport sport is taen. Formatti Formattin' n' the pressure pressure readin' readin' in the formu"a formu"a the 6e"ocit* 6e"ocit* of 5ind and there there coefficien coefficientt of "ift and dra' is ca"cu"ated.
Re/!$t
Thus the ca"cu"ated for coefficient of "ift and coefficient of dra' from an'"e of attac.
22
1? :oeff :oeffici icient ent of "ift"ift-HH HH 2? :oeff :oeffici icient ent of dra'dra'-H.. H..
E3) No) -6
(RESSURE DISTRIBUTION OVER SMOOTH CIRCULAR CYLINDER
Date
A"m
To find the :oefficient of pressure o6er smooth circu"ar c*"inder
Apparat!/ Re!"re7
Susonic !ind Tunne" Smooth :ircu"ar :*"inder 5ith Pressure taps
(ro#e7!re
S5itch LONM the %ain 5hich is connected to the 44 V 32 $ 3 ph $: po5er supp"* 5ith neutra" and earth connection.
:hec a"" the s5itches of the contro""er are in LOFFM position efore startin'. Miniature Circui Circuitt rea!er rea!er ? of :onso"e Board. S5itch LONM the %:B = Miniature
Put&on the mains and oser6e the main indicator "i'hts are '"o5in' at the ottom of the contro" pane".
Fi0 the circu"ar c*"inder in the test section at re8uired orientation. :onnect the pressure taps of manometer to the respecti6e taps of mode". :ontro" the main f"o5 of air in the test section * increasin' the $: motor speed 'radua""*. f rom the P% 6s.Test 6s. Test section Ve"ocit* Ve"ocit* p"ot. Set the speed as constant and note the 6e"ocit* from
%easure and note the readin's from the manometer. $fter the e0periment s5itch LOFFM a"" accessories. Find the coefficient of pressure at each point from ca"cu"ation.
'raph for :*"inde :*"inderr Surface Surface Pressure Pressure 6s. Pressure Pressure Tappin Tappin' ' Points * tain' 0&a0is 0&a0is for P"ot a 'raph Pressure Tappin' Points and *&a0is for :*"inder Surface Pressure.
23
24
Ta!$at"on
Values of "ressure Coefficient over s#ooth circular cylinder $ir at 6e"ocit* - m/s for fre8uenc* - ;
Lo#at"on
Reer) (re//!re@ (r 8#m9
C:$"n7er S!ra#e (re//!re@ (8"9 8#m9
(re//!re/
(m ; 8 (r(8"9 9 8#m9
(T;(m
√ 3 / 2
8#m9
(T (S 8#m9
(S ; 8 (r 5 (1< 9 8#m9
Cp;8(T(S ¿ ! o "5
2
1 2 3 4 # ( ) + 1 11 12 13 Grap?
Plot for s#ooth Cylinder $urface $urface Pressur Pressuree vs.Pressur vs.Pressuree Ta" Ta""in% "in% Points Points
Re/!$t
Thus the pressure :oefficient o6er the smooth circu"ar c*"inder has een found and re8uired p"ot has een dra5n. dra5n. E3) No -F Date
(RESSURE DISTRIBUTION OVER ROUGH CIRCULAR CYLINDER
A"m
To find the :oefficient of pressure o6er rou'h circu"ar c*"inder
25
Apparat!/ Re!"re7
Susonic !ind Tunne" ou'h :ircu"ar :*"inder 5ith Pressure taps
(ro#e7!re
S5itch LONM the %ain 5hich is connected to the 44 V 32 $ 3 ph $: po5er supp"* 5ith neutra" and earth connection.
:hec a"" the s5itches of the contro""er are in LOFFM position efore startin'. Miniature Circui Circuitt rea!er rea!er ? of :onso"e Board. S5itch LONM the %:B = Miniature
Put&on the mains and oser6e the main indicator "i'hts are '"o5in' at the ottom of the contro" pane".
Fi0 the circu"ar c*"inder in the test section at re8uired orientation. :onnect the pressure taps of manometer to the respecti6e taps of mode". :ontro" the main f"o5 of air in the test section * increasin' the $: motor speed 'radua""*. f rom the P% 6s.Test 6s. Test section Ve"ocit* Ve"ocit* p"ot. Set the speed as constant and note the 6e"ocit* from
%easure and note the readin's from the manometer. $fter the e0periment s5itch LOFFM a"" accessories. Find the coefficient of pressure at each point from ca"cu"ation.
'raph for :*"inde :*"inderr Surface Surface Pressure Pressure 6s. Pressure Pressure Tappin Tappin' ' Points * tain' 0&a0is 0&a0is for P"ot a 'raph Pressure Tappin' Points and *&a0is for :*"inder Surface Pressure.
26
Ta!$at"on
Values of "ressure Coefficient over rou%h circular cylinder $ir at 6e"ocit* - m/s for fre8uenc* - ;
Lo#at"on
Reer) (re//!re@ (r 8#m9
C:$"n7er S!ra#e (re//!re@ (8"9 8#m9
(re//!re/
(m ; 8 (r(8"9 9 8#m9
(T;(m
√ 3 / 2
8#m9
(T (S 8#m9
(S ; 8 (r 5 (1< 9 8#m9
Cp;8(T(S ¿ ! o "5
2
1 2 3 4 # ( ) + 1 11 12 13 Grap?
Plot for Cylinder $urface $urface Pressur Pressuree vs.Pressur vs.Pressuree Ta" Ta""in% "in% Points Points
Re/!$t
Thus the pressure :oefficient o6er rou'h circu"ar c*"inder has een found and re8uired p"ot has een dra5n. E3) No) -
(RESSURE DISTRIBUTION OVER SYMMETRICAL AIR&OIL AND ESTIMATION O& Cp
Date A"m
To find the :oefficient of pressure o6er S*mmetrica" $irfoi"
27
Apparat!/ Re!"re7
Susonic !ind Tunne" S*mmetrica" $irfoi" mode" 5ith Pressure taps
&orm!$ae U/e7
1.
Tota" Tota" Pressure - Static Pressure *namic Pressure
2.
For manometer readin's
(ro#e7!re
S5itch LONM the %ain 5hich is connected to the 44 V 32 $ 3 ph $: po5er supp"* 5ith neutra" and earth connection.
:hec a"" the s5itches of the contro""er are in LOFFM position efore startin'. Miniature Circui Circuitt rea!er rea!er ? of :onso"e Board. S5itch LONM the %:B = Miniature
Put&on the mains and oser6e the main indicator "i'hts are '"o5in' at the ottom of the contro" pane".
28
Fi0 the s*mmetrica" $irfoi" mode" in the test section at re8uired orientation. :onnect the pressure taps of manometer to the respecti6e taps of mode". :ontro" the main f"o5 of air in the test section * increasin' the $: motor speed 'radua""*. constant and note the 6e"ocit* from the P% 6s. Test section Ve"ocit* e"ocit* Set the speed as constant p"ot.
%easure and note the readin's from the manometer for different $n'"e of $ttacs. $fter the e0periment s5itch LOFFM a"" accessories. Find the coefficient of pressure at each point from ca"cu"ation.
P"ot a 'raph for s*mmetrica" $irfoi" Surface Pressure 6s. Pressure Tappin' Points * tain' 0&a0is for Pressure Tappin' Points and *&a0is for s*mmetrica" $irfoi" Surface Pressure at certain $n'"e of $ttac.
29
Ta!$at"on
Values of "ressure coefficient over $y##etrical &irfoil $ir at 6e"ocit* - m/s for fre8uenc* - ;
Grap?
Plot for $y##etrical $y##etrical &irfoil &irfoil $urface $urface Pressur Pressuree vs. Pressur Pressuree Ta"" Ta""in% in% Points Points
Re/!$t
Thus the pressure :oefficient o6er the s*mmetrica" $irfoi" mode" has een found and re8uired p"ot has een dra5n. dra5n.
E3) No) -
(RESSURE DISTRIBUTION OVER CAMBERED AIR&OIL AND
30
ESTIMATION O& Cp Date A"m
To find the :oefficient of pressure o6er :amered $irfoi"
Apparat!/ Re!"re7
Susonic !ind Tunne" :amered $irfoi" mode" 5ith Pressure taps
&orm!$ae U/e7
1.
Tota" Tota" Pressure - Static Pressure *namic Pressure
2.
For manometer readin's
(ro#e7!re
S5itch LONM the %ain 5hich is connected to the 44 V 32 $ 3 ph $: po5er supp"* 5ith neutra" and earth connection.
31
:hec a"" the s5itches of the contro""er are in LOFFM position efore startin'. Miniature Circui Circuitt rea!er rea!er ? of :onso"e Board. S5itch LONM the %:B = Miniature
Put&on the mains and oser6e the main indicator "i'hts are '"o5in' at the ottom of the contro" pane".
Fi0 the camered $irfoi" mode" in the test section at re8uired orientation. :onnect the pressure taps of manometer to the respecti6e taps of mode". :ontro" the main f"o5 of air in the test section * increasin' the $: motor speed 'radua""*. constant and note the 6e"ocit* from the P% 6s. Test section Ve"ocit* e"ocit* Set the speed as constant p"ot.
%easure and note the readin's from the manometer for different $n'"e of $ttacs. $fter the e0periment s5itch LOFFM a"" accessories. Find the coefficient of pressure at each point from ca"cu"ation.
P"ot a 'raph for $s*mmetrica" $irfoi" Surface Pressure 6s. Pressure Tappin' Points * tain' 0& a0is for Pressure Tappin' Points and *&a0is for $s*mmetrica" $irfoi" Surface Pressure at certain $n'"e of $ttac.
32
Ta!$at"on
Values of "ressure coefficient over &sy##etrical &irfoil $ir at 6e"ocit* - m/s for fre8uenc* - ;
Grap?
Plot for &sy##etrical &sy##etrical &irfoil &irfoil $urface $urface Pressu Pressure re vs. vs. Pressure Pressure Ta""in% Ta""in% Points Points
Re/!$t
Thus the pressure :oefficient o6er the :amered $irfoi" mode" has een found and re8uired p"ot has een dra5n.
E3) No) 1-
USE O& SCHLIEREN SYSTEM TO VISUALIE SHOC+
33
Date
A"m
To stud* the use of Sch"ieren s*stem to 6isua"i;e shoc
Apparat!/ Re!"re7
Supersonic !ind Tunne" Sch"ieren s*stem
Intro7!#t"on
Sch"ieren method 6isua"i;es the distriution of f"uid densit* 5ithin a f"uid as f"uid densit* contro"s the inde0 of refraction. e'ions of densit* 'radient def"ect "i'ht eams shiftin' their position on the ima'e p"ane. The re"ati6e chan'e in "i'ht intensit* can e used to infer the ori'ina" densit* and f"o5 fie"d. Opt"#a$ (r"n#"p$e
There are se6era" methods common"* used to 6isua"i;e refracti6e inde0 or densit* chan'es in "i8uids 'ases "i8uids and so"ids. enerica""* these inc"ude shado5'raphs sch"ieren and interferometric techni8ues. These s*stems are used to 6isua"i;e temperature 'radients shoc 5a6es in 5ind tunne"s nonhomo'eneous areas in sheet '"ass con6ection patterns in "i8uids etc. Shado5'raph s*stems are often used 5here the densit* 'radients are "ar'e. This techni8ue a"so can accommodate "ar'e suIects is re"ati6e"* simp"e in terms of materia"s re8uired and in terms of cost is proa"* the "east e0pensi6e e0pensi6e techni8ue to to set&up and operate. ,nterf ,nterfero eromet metric ric techni techni8u 8ues es are usua" usua""* "* hi'h"* hi'h"* sensit sensiti6e i6e comp"e comp"e0 0 in set&up set&up can pro6id pro6idee 8uantitati6e information ut are e0pensi6e s*stems and can on"* dea" 5ith re"ati6e"* sma"" suIects. Sch"ieren s*stems are intermediate in terms of sensiti6it* s*stem comp"e0it* and cost. Sch"ieren s*stems can e confi'ured to suit man* different app"ications and sensiti6it* re8uirements. T*pica""* ho5e6er the* are sti"" considered too comp"e0 and e0pensi6e to imp"ement in man* cases 5here a simp"e densit* 6isua"i;ation s*stem is needed.
34
!hi"e discussed and introduced in the ear"* QQs the focusin' sch"ieren method is one that uses no unusua" or e0pensi6e optica" e"ements and *et achie6es hi'h sensiti6it* at re"ati6e"* "o5 cost. P"us it re"ies on "o5&tech s*stem Rin'redientsR. $s *ou can see * the attached i""ustration sho5in' t5o students settin' up a demo s*stem it is perfect for use in teachin' situations 5here cost tends to e a primar* concern. Cn"ie other s*stems the focusin' sch"ieren techni8ue uses a road "i'ht source instead of a sma"" or point "i'ht source. This source is usua""* made up of a re'u"ar arra* arra * of "ac and 5hite e"ements. To mae one re8uires simp"* a "ar'e trans"ucent opa"escent sheet of p"astic onto 5hich opa8ue stripes are fastened creatin' a "ac "ine/ri'ht "ine effect. This screen is i""uminated from ehind 5ith a sin'"e f"ood "amp or a f"ash or a an of them. ,f this screen is "ocated c"oser to the Rima'in'R "ens than infinit* then the ima'e of this screen is reproduced at a distance some5hat "ar'er than 1 foca" "en'th of the "ens. ,f one maes a hi'h contrast ne'ati6e photo'raph of the ima'e of the screen then the ri'ht areas of the suIect 5i"" reproduce as dar opa8ue "ines at the "ocation of the i ma'e of the screen and the "ac "ines 5i"" reproduce as c"ear "ines. Then if a suIect of some ind is p"aced et5een the source and the camera "ens the ima'e of this suIect 5i"" e reproduced sharp"* at a distance "ar'er then that at 5hich a sharp ima'e of the screen is reproduced. This essentia""* means that ima'e points of this c"oser suIect are made up at the focus of the ima'e of this c"oser suIect * "i'ht ra*s that come to the camera "ens from a "ar'e numer of source "ocations. Before these "i'ht ra*s ecome part of the sharp"* focused ima'e of the suIect the* are part of the sharp"* focused ima'e of the source. No5 if the ne'ati6e reproduction of the "i'ht source or screen is p"aced in the position 5here it 5as 5hen its photo'raph 5as made then at an* position farther a5a* from the camera "ens no "i'ht 5i"" e seen ecause a"" the "i'ht from the c"ear areas of the source 5ou"d e stopped * the dar "ines of the reproduction of the source. ,f durin' the Rstead* stateR condition of the s*stems the interferin' ph*sica" reproductions of the 'rid"ines of the source are disp"aced s"i'ht"* from the pint 5here the* cause a tota" e0tinction of "i'ht then a 'ra*ish fie"d of uniform ri'htness 5i"" e percei6ed. This fie"d 5i"" ecome ri'hter unti" the ph*sica" "ines comp"ete"* comp"ete"* co6er the dar "ines "ines of the ima'e of the source source 'rid a""o5in' a"" the the "i'ht present in the c"ear ri'ht areas of the source 'rid to pass.
35
,f the s*stem is adIusted so that the ostruction and the ima'e of the source 'rid are s"i'h"* misa"i'ned and a uniform 're* fie"d is seen then "oca" 6ariations in refracti6e inde0 that cause the "i'ht eam to mo6e 5i"" ecome 6isi"e as "oca" areas in the ima'e p"ane that are ri'hter or darer than the midd"e 're* se"ected that indicates the Rstead* stateR condition. Thus "oca" 6ariations in densit* can e 6isua"i;ed. The* can e recorded 5ith simp"e au0i"iar* photo'raphic e8uipment .
&"%!re ) Operat"n% pr"n#"p$e o /#?$"eren /:/tem
@i'ht ra*s are ent 5hene6er the* encounter chan'es in densit* of a f"uid. Sch"ieren s*stems are used to 6isua"i;e the f"o5 a5a* from the surface of an oIect. The sch"ieren s*stem sho5n in this fi'ure uses t5o conca6e mirrors on either side of the test section of the 5ind tunne". $ mercur* 6apor "amp or a spar 'ap s*stem is used as a ri'ht source of "i'ht. The "i'ht is passed throu'h a s"it 5hich is p"aced such that the ref"ected "i'ht from the mirror forms para""e" ra*s that pass throu'h the test section. On the other side of the tunne" the para""e" ra*s are co""ected * another mirror and focused to a point at the nife ed'e. The ra*s continue on to a recordin' de6ice "ie a 6ideo camera. No5 if the para""e" ra*s of "i'ht encounter a densit* 'radient in the test section the "i'ht is ent or refracted. ,n our schematic a shoc 5a6e has 5a6e has een 'enerated * a mode" p"aced in the supersonic f"o5 throu'h the tunne" test section. Shoc 5a6es are thin re'ions of hi'h 'radients in pressure temperature and densit*. $ ra* of "i'ht passin' throu'h the shoc 5a6e is ent as sho5n * the dashed "ine in the fi'ure. This ra* of "i'ht does not pass throu'h the foca" point ut is stopped * the nife ed'e. The resu"tin' ima'e recorded * the camera has darened "ines that occur 5here the densit* 'radients are
36
present. The mode" comp"ete"* "ocs the passin' of the "i'ht ra*s so 5e see a "ac ima'e of the mode". But more important the shoc 5a6es 'enerated * the mode" are no5 seen as darened "ines on the ima'e. !e ha6e a 5a* to 6isua"i;e shoc 5a6es. The ear"iest sch"ieren photo'raphs of shoc 5a6es 5ere "ac and 5hite ima'es. The ima'e sho5n here is a co"or sch"ieren ima'e produced * puttin' a prism near the s"it and reain' the 5hite "i'ht into different co"ors. Notice that the resu"tin' ima'e is t5o dimensiona" 5hi"e in rea"it* shoc 5a6es are three dimensiona". So the sch"ieren photo'raph pro6ides some 6a"ua"e information aout the "ocation and stren'th of the shoc 5a6es ut it re8uires some e0perience to proper"* interpret the resu"ts of the process. (ro#e7!re
,t is desira"e to use a "ar'e aperture re"ati6e"* "on' foca" "en'th "ens for the ima'in' "ens. Some surp"us copier "enses can e app"ied for this purpose. The source 'rid shou"d e p"aced at a distance e8ua" to four foca" "en'ths of the "ens. The suIect fie"d 5i"" e "ocated at t5o foca" "en'ths from the "ens. Therefore the "ens 5i"" e main' a "ife si;ed reproduction of the suIect.
ue to this choice of distances the "ens 5i"" mae an ima'e of the source 'rid at a distance of 1# inches from the "ens. This can e determined from the asic re"ationship that the reciproca" of the "ensQ foca" "en'th is e8ua" to the reciproca" of the oIect distance p"us the reciproca" of the ima'e distance.
To mae a reproduction of the source 'rid a piece of hi'h contrast fi"m materia" =possi"* stiffened * a piece of '"ass or he"d in or taped to a frame? is p"aced 5here the source 'rid comes to a sharp focus. ,t 'oes 5ithout sa*in' that this must e done in such a manner that on"* "i'ht from the source 'rid fa""s on the photosensiti6e emu"sion. This can e accomp"ished * aff"in' or ui"din' a "i'ht ti'ht o0 around the "ens to fi"m area.
,t is important to note that the reproduction of the source 'rid 5i"" ref"ect an* refracti6e inde0 inhomo'eneities present due to the inc"usion of imperfect 5indo5s in the s*stem and this feature a"one often resu"ts in maIor cost enefits in terms of s*stem setup since re"ati6e"* "o5 8ua"it* optica" components can e used et5een the one "ens in the s*stem and source.
37
$fter the fi"m is e0posed and de6e"oped it is rep"aced in its ori'ina" position. This can e checed * 6isua""* e0aminin' the re'istration et5een the ima'e of the source 'rid and its ph*sica" ne'ati6e reproduction reproduction as 5e"" as tracin' the appearance of the suIect fie"d on a 'round '"ass p"aced as mentioned ao6e at t5o foca" "en'ths from the "ens. ,t shou"d e noted that s"i'ht misre'istration et5een the t5o 'rids a""o5s the operator to 6ar* the ri'htness of the suIect fie"d on the 'round '"ass.
Once this re"ationship has een esta"ished p"acin' a densit* 'radient t5o foca" "en'ths from the camera "ens 5i"" cause this 'radient to e 6isi"e on the 'round '"ass. ,f the source of the 'radients is a hot so"derin' iron for e0amp"e the 5arm air risin' from the iron shou"d e c"ear"* 6isi"e as risin' p"umes of "i'ht and dar from the iron itse"f.
&"%!re )1 S?o#. #apt!re7 : /#?$"eren /:/tem
$ camera can e aimed at the 'round '"ass and ima'es of the disturances created * the risin' densit* 'radients can then u"timate"* e photo'raphed. :on6erse"* :on6erse"* if the 5ho"e s*stem =from the "ens ac to the 'round '"ass? is ui"t in a "i'ht ti'ht container and the "ens is e8uipped 5ith shutter then fi"m can e the u"timate ima'e and e0posures are made * simp"* operatin' the shutter or firin' a f"ash that i""uminates the source 'rid for a rief instant. This is a focusin' sch"ieren photo'raph made direct"* onto fi"m sho5in' 5arm air risin' from hot so"derin' irons. Re/!$t
Thus the use of sch"ieren s*stem to 6isua"i;e the shoc is studied.
V"a !e/t"on/
38
!hat is 5ind tunne" a"ance o5 the shoc induces !hat are the t*pes of shoc !hat are f"o5 6isua"i;ation techni8ues E0p"ain sch"ieren operatin' techni8ue E3) No) 11
USE O& SHADO=GRA(H SYSTEM TO VISUALIE SHOC+
Date
A"m
To stud* the use of Shado5'raph s*stem to 6isua"i;e shoc
Apparat!/ Re!"re7
Supersonic !ind Tunne" Shado5'raph s*stem
Intro7!#t"on
The densit* of a f"uid 6aries 5ith temperature sa"init* and pressure. $nd the inde0 of refraction chan'es 5ith f"uid densit*. Variations in the refracti6e inde0 def"ect or phase shift "i'ht passin' throu'h the f"uid. ,f a screen is p"aced opposite the "i'ht source these effects create shado5s one the screen creatin' an ima'e ca""ed a S?a7o%rap?. Operat"n% pr"n#"p$e
The shado5'raph is the simp"est form of optica" s*stem suita"e for oser6in' a f"o5 e0hiitin' 6ariations of the f"uid densit*. ,n princip"e the s*stem does not need an* optica" component co mponent e0cept a "i'ht source and a recordin' p"ane onto 5hich to proIect the shado5 of the 6ar*in' densit* fie"d. $ shado5 effect is 'enerated ecause a "i'ht ra* is refracti6e"* def"ected so that the position on the recordin' p"ane 5here the undef"ected ra* 5ou"d arri6e no5 remains dar. $t the same time the position 5here the def"ected ra* arri6es appears ri'hter than the undistured en6ironment. $ 6isi"e pattern of 6ariations of the i""umination =contrast? is there* produced in the recordin' p"ane. From an ana"*sis of the optics of the shado5 effect it fo""o5s that the 6isi"e si'na" depends on the second deri6ati6e of the refracti6e inde0
39
of the f"uid. Therefore the shado5'raph as an optica" dia'nostic techni8ue is sensiti6e to chan'es of the second deri6ati6e of the f"uid densit*.
&"%!re 1-) Operat"n% pr"n#"p$e o /?a7o%rap?
(ro#e7!re
,t is e6ident that the shado5'raph is not a method suita"e for 8uantitati6e measurement of the f"uid densit*. O5in' to its simp"icit* ho5e6er the shado5'raph is a con6enient method of otainin' a 8uic sur6e* of a f"o5 in 5hich the densit* chan'es in the descried 5a*.
This app"ies particu"ar"* to compressi"e 'as f"o5s 5ith shoc 5a6es that can e considered as a"terations of the 'as densit* 5ith an e0treme"* intense chan'e in cur6ature of the densit* profi"e i.e. a chan'e of the respecti6e second deri6ati6e.
The oser6ation of shoc 5a6es in 'ases * means of shado5'raph* 'oes ac to the 1+th centur* 5hen these f"o5 phenomena 5ere disco6ered * means of this optica" techni8ue.
40
&"%!re 1-)1 S?a7o%rap? /et!p
ue to the 6er* simp"e optica" setup the shado5 effect resu"tin' from inhomo'eneous densit* fie"ds can e oser6ed a"so outside a "aorator* 5ith the sun ser6in' as the "i'ht source e.'. the sun "i'ht ma* proIect onto a so"id 5a"" shado5 patterns that are caused * fue" 6apor risin' in the air. from the test The camera that records a do5n&sca"ed picture is focused onto a p"ane at distance l from fie"d. This p"ane corresponds to the position of the recordin' p"ane. The intensit* of the shado5 effect or the sensiti6it* of the shado5'raph increases 5ith the distance l . On the other hand the f"o5 picture is the more out of focus the 'reater l so that a compromise et5een optica" sensiti6it* and ima'e 8ua"it* has to e found. The optica" sensiti6it* of the shado5'raph is in princip"e an order of ma'nitude "o5er than that of sch"ieren or interferometric techni8ues.
41
&"%!re 1-)2 S?o#. #apt!re7 : /?a7o%rap? /:/tem
Re/!$t
Thus the use of shado5'raph s*stem to 6isua"i;e the shoc is studied.
V"a !e/t"on/
E0p"ain sch"ieren operatin' techni8ue o5 the shoc induces !hat are the t*pes of shoc !hat t*pe of f"o5 6isua"i;ation techni8ues is more accurate
UNIVERSITY 'UESTIONS
o5 the "ift is 'enerates o5 the 6ortices 'enerates E0p"ain the inducement of "ift and dra' Visua"i;e the f"o5 usin' 5ater channe". Visua"i;e the f"o5 usin' smoe tunne". :a"irate the susonic 5ind tunne" usin' P% method. :a"irate the susonic 5ind tunne" usin' test section 6e"ocit* method.
42
etermine the pressure distriution o6er a circu"ar c*"inder. etermine the pressure distriution o6er s*mmetrica" aerofoi". etermine the pressure distriution o6er a s*mmetrica" aerofoi". $"so find the : P and :. etermine the pressure distriution o6er as*mmetrica" aerofoi" etermine the pressure distriution o6er a s*mmetrica" aerofoi". $"so find the : P and :. s *mmetrica" aerofoi" usin' 5ind tunne" a"ance techni8ue. etermine the force o6er the s*mmetrica" as *mmetrica" aerofoi" usin' 5ind tunne" a"ance techni8ue. etermine the force o6er the as*mmetrica"
E0p"ain Sch"ieren photo'raph* method. o5 the shoc is captured in Sch"ieren photo'raph* method. E0p"ain Shado5 'raph* method. o5 the shoc is 6isua"i;ed in shado5 'raph* method.
