Qualitative and Quantitative Investigation of Honeycomb and Screens Effect in Improvement of Flow Characteristics in a Subsonic Wind Tunnel

HTML
DOWNLOAD

Μέγεθος: px

Εμφάνιση ξεκινά από τη σελίδα:

Download "Qualitative and Quantitative Investigation of Honeycomb and Screens Effect in Improvement of Flow Characteristics in a Subsonic Wind Tunnel"

Πάν Δουρέντης
6 χρόνια πριν
Προβολές:

1 ١ 0-! ! #* ( 3.0 * ( )*# +,#-% (./ # +.0 ' +./ #$% & ' & # ) (" '!"#$ %$ &' ) (" '!"#$ %$ &'(./- )-&'*+, ) %$ &'( * (, +(97% + +(: )6,( /- <! 6 &&= < # :3 6 0 ;8 <, 0 -! 3 4 <. 3 <!3 -&# ; 5 4@> 3 A -!, 3 4 >8 < " ;-. ( 3 0 ;8 3 3 <E 9F K D-L :.( 3 4 D I#J <E 9F! 5 (3 3 4!< *RS! /$ 4 &= 6 X/ 3 0(! IJ 6( &( :.( #( T U( V(! &( < &# 5 D- -C -&# 5 6( *< 3 MN' (- - -&# 5 Q D- Z < :/! :Y+- <E 9F -!' V. Q< E3 3.( -! "3 S 3! /$ &= -! )\ :Y+- 3 4!< *RS -&# 5 $.)\ 0 > 3 IJ 6( > *< < E (! ] ( 3 V :Y+-.T U( V(! &# 5 <E 3 4 :+& +,<%' Qualitative and Quantitative Investigation of Honeycomb and Screens Effect in Improvement of Flow Caracteristics in a Subsonic Wind Tunnel H. Hogoogi B.Sc., student, Isfaan University of Tecnology, Department of Mecanical Engineering M. Nili Amadabadi Assistant Professor, Isfaan University of Tecnology, Department of Mecanical Engineering M. Degan Mansadi Assistant Professor, Malek Astar University, Department of Mecanical & Aerospace Engineering Abstract Wind tunnels generate controlled air flow wic passes troug te model. Tus, a series of useful data related to air flow quality are obtained. Te final goal of wind tunnel design is to generate a uniform air flow wit minimum turbulence intensity and low flow angle. One of te metods for decreasing te turbulence intensity is to install oneycomb and screens in te settling camber of te wind tunnel. In tis researc, te effects of oneycomb and screens wit specified geometric parameters on velocity distribution, turbulence intensity, skewness and flatness are investigated. A set of ot-wire anemometer is used to measure turbulence intensities. It measures flow instantaneous velocity wit ig frequency. Te results sow tat te installation of oneycomb and screens, and isolation of te test section from te fan decreases te turbulence intensity of te test section about 75% and, optimizes te skewness and flatness values. Moreover, normal probability distribution of instantaneous velocity approaces te normal distribution. Keywords: Wind tunnel, Honeycomb, Screens, Turbulence Intensity, Hot-wire Anemometry. Turbulence intensity Honeycomb 3 Screen 4 Skewness (Kurtosis) 5 Flatness 6 Hot wire anemometers * ogoogiadi@yaoo.com :

$uj$ tn D-L : c$ ;-.( <(<3 I 3 &# 5-5\", 9F 9( 3 ( ur( 3 3 4 : 5 'b ur(!( V < :+v.( 3 3 4 : -D-L -34! # S 3! wsj :.3 "3 3' +#A% % 4%@0 -,! IJ 6( Q< 3 < 0(! - & -C'b 5 (J 3 U ( T U( V(!$

2 !< *RS IJ 6( Q< 3 D-L : &( )+ 3!"#$ %$ &' <3 3 4 E 9F < :/ K T U( V(! 5 3 3< K :Y+- % K D-L =!+- :Y+- D I#J.Q E (3! < -&# 6( *< 3 <E K 3, q S 4r -! -&# 5 D-. d,!/$ &=!"#$ %$ &' <3 3 4 ( s! uj$ tn D-L : c$ ;-.( <(<3 I 3 &# 5-5\", 9F 9( 3 ( ur( : 5 'b ur(!( V < :+v.( : -D-L -34! # S 3! wsj :.3 "3 3' +#A% % 4%@0 -,! IJ 6( Q< 3 < 0(! - & -C'b 5 (J 3 U ( T U( V(! &( ^# UI c3@ 3 &!"#$ %$ &' <3 3 4.( #( 3 4 :.( #( D-L : <3 ^ < -' 4! >8 ( %3 3 < *RS 3.(!< *RS K ( r> *RS. 3 6 > 3 4 : 0 3! %( 3 ( +" < E ^ RS 3! -&# 5!\ < D< < 4$> V " : < _Q K 0 -C'b : 3 76.[] ;J %@ S!< *RS '/ *< 3 " 43@ 5K! - :Y , &# Q 3 )\ E3 c+> < &# XE3 :,.[]( 3!.(!3!.[3] (( 'S d -! K 3 &# < e% ' 3 (!< 3 3 %3 ( &# 0( 6( f -!(, 9( -X! UI3 R &# & 56 3.[4] 8 3 #cn S (! -#] <!@3.[5]Q A 3@# -3Q 3!! &#, 46 < :Y+- K! 3 D < E :/! <.[4] < -\! c( 3 ( \3 T U( V(! &( E3 3 X/ 3 0(! IJ 6(! Q< IJ 6( < #( 3 + Q< -D 0(! -C'b g( 6( -! ifa3)! > " < Q < #(!< <D -3< l\3 ks, Z63 l\3 D I#J Rc(.[6]- D-! -C'b : 5 D- 0<! 9( 4J <D (3!< *RS -C'b 08 0 / 79 c$/ <D 3< < #(.[7 6] "'!< *RS < ps...!"#$ %$ &' <3 3 4 < Hotwire Anemometry Trip strip

3 &'! ( $%! # "! C*9 +.E0-4 +#A% % +%FG HI# 30 ' *@ ! 6( T U( V(! &( # + (3 I 3. Q< IJ :U" <. MN' S 3 0(! w8 ( g( 6( 0(! -MA U 5 mean e% N ( n ).[8] e%() % U () = N MN' 0(! 6( % ;J () % w8 ( 0(! -&#.[8] N u ( ( ) ) () rms = U n U mean N 5! 0(! 6( % ;J < #( 3 T u.[8]+ e% < 5$ 3 0(! -C'b u rms = 00% U mean 0.5 (3) 0(! # (3 & U"!3 &= S.( /$ &= ( #(! 6( :& 3 IJ 6(!S!\ /$!\!3 /$ S >.( 0( : >8.(! *< IJ.[8] -'! 3-4 [8] &= d"# >8-3 [8] /$ d"# >8-3 3 U( < #( 3!< *RS J -C'b 5 \/d. Q<! 5Sc% #] ) T " - _A I 3 T U( V(! 3 y , 3 l 3 5 < C< )+ 3 * 6( :Y+-. #(. Q< 5 C*9 D % B' 5zz zzq<zz zz3 zz3 _zza Xzz/ -3 \-zc T U( V(! g(! -C'b 4@ I RS 3 + % zz( 5zz$ zz3 T Uzz( &zz( zz3 < zq< 3 *R@ X/ ( 3 IJ 6( Q<.( tn \-c 0 5z zq<z :zy+- T Uz(!( I 45z6z( > < ecn 6( 0 -C'b > 3 -Q< c.(/q d, K 3 < z%3 4z@ z3 4z 3 < :/! \ < %3 4@ Uz( 9zF 4zJ /Q 5$ - <E 9F zf z(!z<{ < & ys \ T!<*RS 6( *< Q z3!z<{z \z RS Q< ecn!<{! # w@ (3 I 3.( \z \z urz( z& yzs &#z 5z!\z S :!3 3' <!+8 < X Q< z S z3 zrs :z 5z678 < \z RS S 3 z/q zi z S 3z' y ( #( ZJ3 D-L : 4 3 ( s 43@ :Y+- D- 3 -! K (3 9( < E tn z3 3 4!< {! &# 5 z3 4z z z> &# S Q< _ ( (* 4) &# 5 D- " \", }- zz tzz, zz( zz3 zz3 zz= zz( zzv z- 5\", ^ % > d, -Q<..+ (J 4r &# 5 3

4 6 6( 0c( 3< < g3 :.( <E 3 6( 3< 3 < - R@ < E 3 / 9v S! - *RS ur( / 0 / 3 33 f c b a '/.[] /Q I 0 / [] < E ecn ^ -4 3 < E g( -C'b 5 D-!\.[]+ (J < 5$ 3! ( Tu ) after + α α k f = = (8) ( Tu ) befor + α + k 3 < 3, R3 < 3 DA= 9v α! α =. + k.[] ( (9) -3Q ( 5$ :3 d\ 6 < X - - ( < Q\3 -!. U S )= -3Q 3 A <. :3 < ( : \ )= -3Q : -C'b < "3! J -C'b - D d E+% ). U 3 D. MN' ( /3! < +( R@. #Q! 08 < } ) - ( % #( -C'b 5 D- 3-9v!+- 4 > 3 <3 > Q\3 0 / 57 < 3 (J (0) R3 < ( β ) 0 / 57 < = - 3 5$ : b. 3 3 < 6 :Y+-.! 4' > : < '3 3 U( R@ # 5$ 3 ( U( < -! -.[] :3 <! ( : 3 β d = l ( & < U( c$/ 5.4 l = Mes (0) l U( R@ d :3 ( 33[] * e% w8 () < g3 <! - : e% w8 S = N ( U ( n ) U ) 3 mean 3 N u rms N ( U ( n ) U ) 4 mean 4.[8] (J (4) K = (5) N u rms d6!3 ( \ d(!+!+- &= 3 0(! IJ 6( J!S w3r ( 3 - $. 3 :& #$ 33 &=!\!S *< 3. \ d"=!+!+-! /$.[](!\ *< J 3 &= *< J Q'!\ "Q )!\ 4$. /$ Q &=!3 /$!\ g( 0 *< 3 *< +.[]( 333 Q 0 *< 3 S :. +.0 ' +./ #$0 # J&7 +.E0 K%' --4 )*# H & +' < D- 0 - : D I#J 4 : ! -< E E+%. #( \ < E < d < ( CQ D *8S 3 -A ( < 3 CQ D < E 3. A(.[] /Q I 0 / 33 k '/ / 9v -< E / 9v (J 3 ( s!.[]/q )+ < g3 <! L k λ 3 (6) = + D β β R@ D 0c( 08 > '/ / 9v λ!! " < E 08 0c( - β L.( < E 4 ur( 3 <3 ur( 6 0c( 3< - R@ < %3 λ S.[] (J < 5$ 3 3 0c( < 0.4 λ = Re > 75 D Re Re 75 D (7)... 4

$&'! ( $%! # "!!< *RS&# 5 3 3 < :/ D K -4 3 D -!'> &# :& S *RS &# 5 $ 6 > 3 4 : 3 < :/!3 3 4> :.( D-!< &# 5 34 \ 3 \ &# 5 D- c6.( 3 < E 5 % D- > : \ ( s 43@. 3-4' c$ *3-3Q 3 +- 3 4 3 < :/! 3 _.$

5 &'! ( $%! # "!!< *RS&# < :/ D K -4 3 D -!'> &# :& S *RS &# 5 $ 6 > 3 4 : 3 < :/!3 3 4> :.( D-!< &# 5 34 \ 3 \ &# 5 D- c6.( 3 < E 5 % D- > : \ ( s 43@. 3-4' c$ *3-3Q < :/! 3 _ ) \, ' 4S :/ U ( 5 % 5, / D- " 43@!\ 3.3 D-\ %R 3 4 &# () R3 5$ 3 '/ / 9v (J R3 55. k = k 0 + Re d k β = 0.95β :[]( ()! (3).( U( R@ 3 < 6 Re d ( s! < #( 3 6( -C'b 5 D- (J 3 -q : r. / -q - :&+- -C'b 3 -C'b 5 D- (J D-!\ %@! ( :+ : N+- qs 3 -C'b 5 -C'b 5 D- 3 < % 933 0( #( = < &- J.[]+ f = (4) u + k : 3 y' 6 n 3 {/ % 3 3 < )- '/ / 9v ^+, 33 k '/ / 9v R3 w8 -! -C'b 5 D- 3 - f u = ( ) + k n /.[] (J < (5) D-L : < :/ D J ( -( 3 3 0>! 9F < X Q 9F 9( < E I!< *RS &# 4@ 3' 7 R & 3 5 D- < E K!3 Q< S :, 6 (3 &#.-!' L*- -5 #0 L*- --5 D < 4@ 3) < E 9F! < :/ D < %3 & < :/ V S 4 4 d, 3 3.(!' > : 3!< *RS &# - UJ 3 <( <( < -! 3 > ( :/ ( "3 - A3 \ 9( 3 3 :/! < 5 %! 3 < <( S 3 +- :.& 4S!< *RS, d, D-L : w3r 3 4.( 5

6 ...!< *RS &# 5 3 E 9F K -73!<*RS &# 5 3 < E 9FK " K < E.> -!' V -! K :+v. 6(! A.( / D- 3Q 'A= < 4@!< { \ J#$ 6( 5f -83 < E 9F < %3!< { \ J#$ 6( 5f -93 < E 9F < E 9F -!' &# 5 V :& 4 :.- D- &# 5 $ 65 / 4 > 5 " < E.> -!' 3A 3 " *< c3 D- -6( + &# 30 6( < %3 4@ <3 S A \ 3 ƒ : 3K S &# 5 K 3 DS < E %$ 3 4 ). D I#J! yra! < (( < E < #( 3 " -!' - (3 ( 34 0@ 43@! # 3!+.( "' :SSJ g( - < #(! '3 D-, l\3-3q : 3 _ I#J 9(!< *RS 5 'b 5 w8 3 Q 9F < E ( : D. Q<!< *RS &# 5 4@ 3' $ 3 / D- 9( E 9F I>7 "' 74 S :,.( &# 5.( 3 76 < E 9F -!' v> V 4/ "3 9(!< *RS &# 5 D- '3 =- A SS> *RS : 6( - J$ \ 3 Kƒ U" : ( 6( A V J$ = 34 ys t )+ 3. *RS! 5 3!< I#J *RS ur( *RS g( 6( 5f w3r 3 - < E 9F < %3 4@ 3 4.( ( 6

7 # "! 4/ 3 < E 9F K + S 3 > ( \ ga ys 6( 6( : 3 3.( U( () (0)4 < E.> 3 6( *<! A 4.( "' 7- $%! &'! ( 6( 3 &= 5f -3 < E 9F < 4@ \ ga 6( *< -03 6( 3 /$ 5f -33 -!' 4 w3r &= 5f #$ S 3 -!S < E 9F K ] : ( '3 -'! :Y+-. 3 &# S 3 /$ S < E 9F < X -6( +!6 3 ( )\ "3 % "3 S 33 S S : K 3 0 )\ &= *< J Q' < &!3 3.( 3 : F! + % *< 3 -A D- &# 5 ( + *< Q! - *<, 5# :+-./ v w3r ' " < E 9F -!' A + -c@!\ c3 &# 5 S D- Z63 Q *< 3 - *< - D- \ + : > *< Q : )\ J, 5# 3A 3! U( > -+ "3 S I 3. -' - *< 3 0 *< 3 -! )\ 0 0+> *< < E 9F < %3 \ ga 6( *< , ) 6 (3-4cJ ( 3! (Q *< < - ;J.( d6!3 &=. (3 &= /$ 3 0(! IJ 6( J!S &= *< J Q'!\ /$ :& #Q 8!+-.( Q &= *< J 3.( 3 33 /$ 3 #$ 33 &= 3 "3 S 6( 3 /$ &= 5f 3 4.-!' < E 9F < %3 4@ > Normal Probability Plot Gaussian distribution 7

8 6 4 w3r Q d, - D-/ ( "3. c/ - -C... - D- K -63!' -! 0 *< *3 3 - D- K 7 4 > 3 -! *< - D- 3 9 :3.-. S -! "3! ( )\ 0 -!' w3r - 0 *< )\ - *< "3 9( < E 9F -4 8!+-. ( 0 *< 3!! ys < E 9F < %3 > ( MN' / D- 0 *< 3 -! ;7A )\ ga 3 / -+ \ -6( S3 3 ( #Q.(. - "3' < E 9F < 4@ (K3 306() < E 9F < % (K3 306() #(! +( Q0& 6 C 3 - RS \ *< Q 3 f ( x ) *3 3! +( C c R3. )\ f ( x i ) = ( f ( x i ) + f ( x i ) + f ( x i + )) 4.( < 5$ (4) - *< 3 - D- K -73 Data Reduction Process Simpson Numerical Integration 8

9 &'! ( $%! # "! U( R@ 3 < 6 (J 3 ( #Q - ia K 3 5 D I#J 6( &( g( Q< ) Q ( 0.( /Q I (T U(V(! C'b 5 D- 9v 5(J V -P' D'( / 0 / 7 / 07 0 / 34 0 / 87 P'% / 0 / 5 0 / QR: ( c) U( R@ M} - D % l(c) D %3 K'/ / 9v (J q 9v Q< 3, 9v <E 9F <%3 0 0+> (K3 306() S ;7A < E 3 8!+- g( &# 5 D- 9v 3 3, q /Q,! :33.( $ 50 < D3 3 \ - 9v : w@ (J 3 Q< C :"3. 3 +#*S%#0 ' TU V RA 3, -Q< d, :> +- 3K -RA : U S ( 3 "! 3K -RA.(_) /F -RA ()+ () 3 4 :+- 3 (! -Q<. -! ;_> 43@ 9( 5JJF!( 43@ :33 #!A 3-3 /F -RA RA 0+> 3 %R@ d6 4cJ ;-. ;_> RA *3 c+ <.( 3, V /F -RA 3! T U( V(! 3 Q< -C<!( J 3-5 RA :% < -RA RJ g "Q D-L : ( V.( /Q 5$ -3 %R@ d6 < 3< XE3 5 Q< %R@ d6 -!' s 43@. 3 $ 5 g( 6( $ 3 >./ {# : -6( %R@ d6 :'3 ( 4 )!< *RS &# 5 +#A- D-L : -6 3 < E 9F K Q< 5$ < 3!< *RS! ecn - &# 5 <E 9F < 4@ 0 0+> (K3 306() #0 ' +.E0 L*- O*6-3-5 ^ < 3 4 : 9F < E 3 Q 6 / 33 0c( - R@ 3 CQ D ( c 38 / >! " 08 c d, -&# 5 D- 9v 3 y3 5(J 33 &# 5 D- 9v S I>7 3, V < ( > : (3 0 / 8 : []!+- 3. (3 0 / v : :!3 ;7A : 3 ) * \ $ 50 ( :+ < E 3 ;7A.[](3 5 D- 9v!3 g3 w8 3 \ 3 S 3, S 3 X ( (J 5 'b 5FN' 3 3 5(J :,.+ Barlow.( 0 9

10 /$ '/ / 9v < E '/ / 9v < E &# 5 D- 9v &# 5 D- 9v K k k f f u V%# [] Barlow, J.B.; Rae, W.H. and Pope, "A Low-Speed Wind Tunnel Testing", Tird Edition, Jon Wiley and Sons, 999. [] Owen, F.K., "Wind tunnel flow quality" retrospect and prospect, 38t Aerospace sciences meeting and exibits, AIAA &# D- 3 ", '!S- [3] ' e %$ &' "5$! !./- (" [4] Degan Mansadi. M, "Te Importance of Turbulence in Assessment of Wind Tunnel Flow Quality", Wind Tunnels and Experimental Fluid Dynamics Researc, Edited by Jorge Colman Lerner and Ulfilas Boldes, Intec open access publiser, capter, 0. [5] Bradsaw.P, "Te Understanding and Prediction of Turbulent Flow - 996" (presented at Engineering Foundation Conference on Turbulent Heat Transfer, San Diego 996), Int. J. Heat and Fluid Flow, vol. 8, pp. 45, 997. [6] Soltani M.R., Gorbanian K. and Mansadi M.D., "Application of Screens and Trips in Enancement of Flow Caracteristics in Subsonic Wind Tunnels", Mecanical Engineering Vol. 7, No., pp. - Sarif University of Tecnology, 00. [7] Finn E. Jorgensen, "How to measure turbulence wit ot-wire anemometers", a practical guide, DANTEC Dynamic, 00.!S- : J <!3@ v+j Rc( [8] D- 3 ps '/ *< "3", ' e ) (" c, "3 4 &#.3889-i < :/! 3 (3 #! < E ) A! 'N3 "3!< *RS!., *RS 9F < :/! -!' V! &# 5 $ 75 > < E I>7 :Y+-.( D-!< *RS D- 9v S Q< 3 q g3 3 < E ^ ) 3 9( &#.%3 T U( V(! 3 Q< S ( 9cR : ] V (3. ;7A $ 50 &# 5 D < E \ /$ &= c+ < 0(! - 9F < X &!3 3. )\ "3 S 3 > 3 0( IJ 6( - *< < E > *<-+. )\ (Q 0! wsj : V <. wf V : 3A.+ #( 3' -3 4! # S,(: -7 -D< w@ SSJ '-L ( d<e - d, -! )+ 3 ( > - 0 / < +): 3!< *RS! &# %!\/ 3 76! I : ($ < #( 4r -C < (6 4 r> E+%) - f ps tj > < D 3<!< *RS 5 'b 5 ps '/ *< E+%) E3 ks 3 :Y+-.[7] D- &# ) >8 <E (0 < '3.( : 3,+%@WX!@ +- < d<e A 3!Q d, +J - + : >+J : +> < ( :Y+-. \Q ( -D< : < -z+>./- %( ( S!"#$ %$ &' 3 4 S D-L... &# 5 &=,( T u S 0

Σχετικά έγγραφα

ΘΕΩΡΗΤΙΚΗ ΚΑΙ ΠΕΙΡΑΜΑΤΙΚΗ ΙΕΡΕΥΝΗΣΗ ΤΗΣ ΙΕΡΓΑΣΙΑΣ ΣΚΛΗΡΥΝΣΗΣ ΙΑ ΛΕΙΑΝΣΕΩΣ

ΘΕΩΡΗΤΙΚΗ ΚΑΙ ΠΕΙΡΑΜΑΤΙΚΗ ΙΕΡΕΥΝΗΣΗ ΤΗΣ ΙΕΡΓΑΣΙΑΣ ΣΚΛΗΡΥΝΣΗΣ ΙΑ ΛΕΙΑΝΣΕΩΣ ΠΑΝΕΠΙΣΤΗΜΙΟ ΠΑΤΡΩΝ ΠΟΛΥΤΕΧΝΙΚΗ ΣΧΟΛΗ ΤΜΗΜΑ ΜΗΧΑΝΟΛΟΓΩΝ ΚΑΙ ΑΕΡΟΝΑΥΠΗΓΩΝ ΜΗΧΑΝΙΚΩΝ ΕΡΓΑΣΤΗΡΙΟ ΣΥΣΤΗΜΑΤΩΝ ΠΑΡΑΓΩΓΗΣ ΚΑΙ ΑΥΤΟΜΑΤΙΣΜΟΥ / ΥΝΑΜΙΚΗΣ & ΘΕΩΡΙΑΣ ΜΗΧΑΝΩΝ ΙΕΥΘΥΝΤΗΣ: Καθηγητής Γ. ΧΡΥΣΟΛΟΥΡΗΣ Ι ΑΚΤΟΡΙΚΗ