Post on 06-Feb-2018
. &
( 2004-2005) : . . : .
1
1.2: , :
A Hg 30cm
2.1 20cm 10cm H2O 2.2 ( )
H2O
1.2
1121 ghPP = , 2223 ghPP = , 3334 ghPP = kPa3.14ghghghPP 332211aA =+= , kPa6.115PA =
1.3: , :
F 0,5m 1m
3.1 H2O 2m 3.2 ()
3.3 F A A 1m
1.3 : h=0.5+1=1.5m, Fp=gh=29.43 kN
:
=
y
x 'y'x' ,
=
y
y 'x'x'
m0x0 ''y'x == , m222.0ym667.012bh '43
'x'x ===
x=1.5+0.222=1.722m,
kN25.27FlFlF pp == (lp=2-1.722=0.277m, l=3m)
2
2.1 3.55 ( Bernoulli) 2.1 (3.55) ( . )
3 30.00130 30 0.03sec sec secl l mQ
l= = =
m,
2
0.03 1.6980.15 sec( )2
Q mVA
= = =
hf: 2 210 10(1.698) 1.469
2 2(9.81)fVh m g
= = =
s: 1 1 2 21 22 2 s fP V P Vz z Hg g g g
h+ + = + + + +
(P1=P2=Pa, V1=V2=0) => 1 2 16 1.469 17.469s f s fH z z h H H h m= = = =
: ( n = 80% = 0.8) theoriticalactual
PnP
= =>
1000(9.81)(0.03)(17.469) 16426.408 6426.408 8.6140.8 746
sgQH HPP Wn W
W HP= = = = =
2.2 3.57 ( Bernoulli) 2.2 (3.57) ( . )
3 3 1120000 120000 33.333600sec sec
m m hQh h
= = =3m
s: 1 1 2 2
1 22 2 s fP V P Vz z Hg g g g
h+ + = + + + + ,
(P1= P2 = Pa, V1 = V2 = 0, hf = 0) =>
1 2 60s sH z z H H m= = =
n = 80% = 0.8) actualPntheoriticalP
= => (
11000(9.81)(33.33)(60)(0.8) 15694430.4 15694430.4 21038.11746s
HPP n gQH W W HPW
= = = = =
2
2.3 3.88 ( )
2.3 (3.88)
) ( . s/m0555.0Q 31 = , s/m3333.0Q
31 = , s/m2222.0Q
31 = ,
kPa6.68P1 = s/m49.3V1 = , s/m7. 24V2 = , s/m8
5.12V1 = 2 3. Bernouli (1)-(2): (z1 = z2 = 0)
+=+VPVP 222
211
g2gg2gP2=-63,66kPa
. Bernouli (1)-(3): (z = 0) 3
+=+VPVP 233
211 P =-4,13kPA
g2gg2g 3
x: x3
032
02 Q60cosVQ45cosV =+
(F2x = P2A2cos45 , F3x = P3A3cos60) => Fx = 2.9 kN ( )
y:
3sin 60oV Q+
(F1y = P1A1, F2y = P2A2sin45 , F3y = P3A3 sin60)
( ) ( ) x3x2 FFF ++ 3
1 2 3 1 1 2 sin 45o
y y y yF F F F V Q V Q + + + = + 2 3
=> Fy = 6.21 kN ( ) 2.4 3.114 ( ) 2.4 (3.114)
) x:
u = (V0 u) A u
u
:
1 0
( . Fx = (V0 u)2 A => Fx = (V0 u)2 A H W : W = Fx 2 H W u W(u) = u (V0 u)2, W' = (V0 u)(V3u), W'' = 2 (3V0 2u)
u2 = 03. H V
V u = V 0
2 V 0 > 0, 03V
2 V0 < 0.
03
V .
3
3
3.1 Vo=8m/s SAE 10. W=0.5m L=1.0m. , :
1.1 (L=1m) 1.2 () 1.3 1.4 ,
3.1
3.1.1 =
= 40 10x9LV
Re
m0183.0Re
L5.5
L
== , 0022.0Re664.0c
L
f == , 0044.0c2c fD ==
3.1.2 N129LWV21c2F 20DD ==
3.1.3 W1033FVP D0 ==3.1.4 , N183FD = , W1465FVP D0 == 2 Navier-Stokes :
( U + V ) = - [ ( ) + ( )]t x y x x x y
U U U p U Uy
+ + (1)
( U + V ) = - [ ( ) + ( )]t x y x x y
V V V p V Vy y
+ + (2)
2.1 (=C) . 2.2 , ;
3.2 3.2.1 (=C) :
d dU dp ( ) = dy dy dx
p = 0y
3.2.2 : U U p(U + V ) = - ( )x y x y
+ Uy
p = 0y
: V ~ 0