. : 2013 - 2014

1

( ) = () ()

.. l = 3.2 ft

:

1

2

3

(SI)

C.G.S

( F.P.S.)

( )

: 1 oz 1ton long 1ton metric 1 ton short

( = 28.35 g,

) ( = 1016 g) ( = 1000 g) ( = 907.18 g)

: 1 1 in 1 mile

( = 10-8 cm) ( = 2.540 cm) ( = 1.609 Km)

: 1 ft3 1 in3 1 gal U.S. 1 l

( = 28.317 cm3) ( = 1.64 10-5 m3) ( = 3.785 10-3 m3) ( = 1 10-3 m3)

l L

M m M

t T

S L2

M L-3

u L T-1

(SI)

SI , . , SI , , .

:

1) ()

2) :

3) k1 k3

, , , ,

Kg m s K mol

(SI)

FPS

, ,

ft lbm s (= 30.48 cm, (453.6 g,

foot, ) pound, )

: 1 poundal 1 lbf = 1 lbm ft/s2

gc , lbm lbf

1 gc

F = m g g=32.17 ft/s2

1lbf 1 lbm gc = 32.17

lbm ft

lbf s2

= 1 gc

m g h m u2 = 1

2 gc

,

ft s lbf (foot, (pound force)

)

: 1 slug = 1 lbf s2/ft

760 mm Hg

Fa

hre

nh

eit

Ra

nk

ine

Ke

lvin

Ce

lsiu

s

0 0 -460 -273

oC = oF -40 420 233 -40

0 460 255 -18

32 492 273 0

212 672 373 100

180 180 100 100

oF = oR - 460 K = oC + 273

o

C =

o

F =

0

R

oF 0R

oC = = 1.8

oF - 32

oC =

5

9

N2

h N2

h

SI 1 Pa = 1 N/m2

CGS 1 dyn/cm2

FPS 1 psi = 1lbf/in2

1 atm = 101.3 kPa

= 14.7 psi

= 760 mmHg

1 cmHg, 1 mmHg, 1 inHg

= +

psia = psig + 1 atm = psig + 14.7 psi

SI 1 J = 1 N m

CGS 1 erg = 1 dyn cm

FPS 1 ft lbf

/

SI 1 J = 1 N m

CGS 1 cal = 4.1868 J

FPS 1 Btu = 252 cal = 1055.1 J (British thermal unit)

= k m

-

k = 1 cal / g oC

k = 1 Btu / lbm oF

: J = 4.1868 J / cal

/

1.

2.

.

.

3. ,

, .

.

4.

.

.

5.

.

.

Buckingham

" , (n-m), m "

-

/

, . D [L]

k [M L -3 -1]

v [L -1]

[ L-3]

[M L-1 -1]

Cp [L2 -2 T-1]

h [ -3 -1 ]

: .

: , L: , : , :

n = 7

m = 4 n-m = 3

= (1, 2, 3) 1 = (2, 3)

i (i = 1..3)

= D k v C hp

= L ML

T

L

M

L

M

L

L

T

M

T3 3

2

2 3

= L M T 3 2 3

++-3-+2 = 0 (3.9) +++ = 0 (3.9) -3---- = 0 (3.9) --- = 0

= 1

= = 0

= 1 = -1 = = 0 1 Nu =

h D

k

Nusselt

= 0 = 0 = 1

= 0 = = 1 = -1

2 Re = v D

Reynolds

= 1 = = 0

= = 1 = -1 3 Pr =

C

k

p

Prandtl

Nu = a b cRe Pr