Лекции по гидрогазодинамике
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µ
Re λ
dx
x dτ
dx
c = dx/dτ
dV = S dx dτ S
v dm = v ρ S dx
dτ
p
0
+ ∆p
p
0
dV ∆p S dτ
v ρ S dx = ∆p S dτ.
∆p = ρ v c.
ρ = 1000 /
3
v = 2 /c
c
0
= 1414 /c
∆p = 1000 · 2 · 1414 ≈ 2.80 · 10
6
= 2.8
e = e
( )
+ e
( )
.
L d
e =
ρ v
2
2
V =
ρ v
2
2
π d
2
4
L.
e =
σ
2
V
2 E
,
σ , E , V
σ
∆p
e
( )
=
∆p
2
π d
2
L
8 E
( )
,
∆p S = σ S .
S = d L S = 2 δ L
δ
σ = ∆p
d
2 δ
e
( )
=
∆p
2
d
2
4 δ
2
π d δ L
2 E
.
∆p = ρ v
v
u
u
t
E
ρ
v
u
u
t
1 +
E d
E δ
= ρ v c.
c =
c
0
v
u
u
t
1 +
E d
E δ
,
c
0
=
q
E /ρ
∆τ
τ = L/c) ∆τ
∆p = ∆p
τ
∆τ
.
∆τ
∼ 1%
p
κ =
p
∞
− p
k
0.5 ρ v
2
∞
,
p
∞
, v
∞
p
κ
κ
p = p
κ
v
∞
=
v
u
u
u
t
2 (p
∞
− p )
ρ κ
.
v < v
∞
v
r
= f(r) r
Q = v
r
S = v
r
4 π r
2
= v
R
4 π R
2
= onst.
R, v
R
v
r
= v
R
R
2
r
2
.
r > > R
e = −A ,
1
r
2
d
d r
r
2
v
r
= 0.