CHAPTER-7 CASCADES.pdf

8/13/2019 CHAPTER-7 CASCADES.pdf

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. . . . . ! " ! "

#. $ % &

'. ( ! " " ). * +. , -. / . 0 1. . $0 0

Cascade Nomenclature

.

. $0 . $2 #. 30 '. 4 / /4 ! 4

56708 9

). / / ! 56708 9

:8 !;

Prepared by Dr. S. Ramamurthy, [email protected]


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ero!oil representation

"ritish Practice#

ero!oil built around basic circular or parabolic camber line

$2C%&3' P30 Denotes an aero!oil !or (hich the ma)imum thic*ness to chord ratio+t&c is $2-, C% denotes

the base pro!ile, 3' is the camber angle in degrees, P denotes a parabolic arc camber line and 30 is the

percentage o! the chord !rom the leading edge (here ma)imum camber occurs.

merican Practice#

Series o! aero!oils deeloped by NC+National disory Committee !or eronautics

series o! camber lines used, each associated (ith design li!t coe!!icient +C/ o! a single aero!oil.

NC 1'+$2$0

Camber line corresponding to C/$2&$0$.2 and a pro!ile shape 1' (ith appro)imate $0- thic*ness.

rdinates !or other camber are obtained by direct scaling in proportion to the camber C/



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Construction o! C% 4 C5 compressor blade base pro!iles

% Chord t/2 NACA 65 Series t/2 for C4 t/2 for C7 t/2 for T6

0 0 0 0 0 0.' 0.552

0.5' 0.632

$.2' $.$16 $.1' $.'$ $.$5

2.' $.'5% 2.25 2.0% $.'%

' 2.$55 3.07 2.52 $.66

5.' 2.15% 3.12 3.$7 2.35

$0 3.0% %.02 3.'% 2.5%

$' 3.111 %.'' %.0' 3.%

NC 1'$0

Coordinates o! "ritish C% ,C5, NC1'$0 and 81 base pro!iles

. . . .

2' %.'03

30 %.51 ' %.71 %.52

3' %.62%

%0 %.661 %.76 ' '

%' %.613

'0 %.7$2 %.'5 %.71 %.15

'' %.'3

10 %.$%1 %.0' %.%3 3.5

1' 3.172

50 3.$' 3.35 3.53 2.'$

5' 2.'7%

70 $.635 2.'% 2.57 $.%2

7' $.37'

60 0.7$ $.1 $.1' 0.7'

6' 0.301 $.01 $.06 0.52

$00 0 0 0 0

/9 Radius 0.175- o! C $2- ma) t $2-ma) t $2- ma) t

89 Radius Sharp 1- ma) t 1- ma) t 1- ma) t

3Di!!erent air!oils used in

8urbo machines

C%


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Coordinates o! NC 1' Series air!oil +see table 7.2

)&c- "ase Pro!ile t&2

rdinate and slope o! mean camber line !or Clo$.0

rdinate y&c - Slope dy&d)

0 0 0

0.' 0.552 0.2' 0.%2$20

0.5' 0.632 0.3' 0.3775'

$.2' $.$16 0.'3' 0.3%550

2.' $.'5% 0.63 0.26$''

' 2.$55 $.'7 0.23%30

5.' 2.1%5 2.$2 0.$666'

$0 3.0% 2.'7' 0.$5%7'

$' 3.111 3.31' 0.$370'

20 %.$%3 3.67 0.$$030


NC 1' series o! cascade aero!oils

+/.:. ;erring ,:.C. 9mery and :.R. 9r(in.

Courtesy NC

2' %.'03 %.%5' 0.075%'

30 %.51 %.71 0.015%'3' %.62% '.$' 0.0%62'

%0 %.661 '.3'' 0.0322'

%' %.613 '.%5' 0.0$'6'

'0 %.7$2 '.'$' 0.00000

'' %.'30 '.%5' 0.0$'6'

10 %.$%1 '.3'' 0.0322'

1' 3.172 '.$' 0.0%62'

50 3.$'1 %.71 0.015%'

5' 2.'7% %.%5' 0.075%'

70 $.675 3.67 0.$$030

7' $.37' 3.31' 0.$370'

60 0.7$ 2.'7' 0.$5%7'

6' 0.301 $.'7 0.23%30

$00 0 0

/9 radius 0.175

NACA 65 Series Compressor blade profiles


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Section o! pro!iles in use in a)ial machines


Common camber line shapes

Suction 4 Pressure Sur!ace


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"lade setting ariables

=lo( 4 pressure distribution

=lo( 4 pressure distribution

Root and tip sections o! a typical

Compressor rotor blade illustrating

8he degree o! t(ist



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, 4 !479 @F D>@ HIJ79 " >@ HIJ79E!5>@F DHIJ79 "HIJ79E = = = 79

BC C 79 79 5>@

79D/479 < /79E !5>@F DHIJ79 "HIJ79E

/479 < /79 ! DHIJ79 "HIJ79E79K2 /4/ 001. / /4 !

DHIJ79 "HIJ79E79

LMNBO ! PL Prepared by Dr. S. Ramamurthy, [email protected]


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: C Q ,05

CHAPTER-7 CASCADES.pdf

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