16.512, Rocket Propulsion
Prof. Manuel MartinezSanchez
Lecture 11: Radiation Heat Transfer and Cooling
Radiative Losses
At throat of a RP1LOX rocket, evaluate radiation heat flux
c
P
70atm
=
c
D
0.21m
=
c
T
3500K
=
O /F
2.2
=
γ
=1.25
M=25 g/mol
o
c
x
0.3
±
8
1
4
1
2
H O
x
0.3
=
2
H
x
0.1
±
2
co
x
0.1
±
γ
γ−
⎛
⎞
=
⎜
⎟
γ +
⎝
⎠
1
throat
2
P
1
c
P
38.85atm
=
co
P
14.8atm
=
2
H O
P
12.0 at
=
m
m
m
2
H
P
5.4at
=
2
co
P
4.3 at
=
=
=
=
γ +
throat
c
2
T
T
3111K
5600R
1
Assume slab if thickness L=0.9
t
D
0.191m
0.63ft
=
=
(
)
co
PL
9.2ftatm
=
(
)
2
H O
PL
7.5ftatm
=
(
)
2
H
PL
3.4ftatm
=
(
)
2
co
PL
2.7ftatm
=
16.512, Rocket Propulsion
Lecture 11
Prof. Manuel MartinezSanchez
Page 1 of 14
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CO
Fig 422 for CO gas only to 2400 R
2 ft atm
So, extrapolated to 9.2 ft atm,
(
)
2400R
0.1
ε
±
at 2400 R. But
ε
falls rapidly with T.
If we conservatively extrapolate linearly in Log
ε
(T).
co
ε
would appear to go to ~
0.005 or so. Hence, even though the gas is COrich, radiation by CO is negligible
.
2
H O
At
,
PL
, Fig 4.15 gives
T
P
1atm
=
7.5ftatm
=
(
)
2
H o
5000R
0.18
ε
=
, and extrapolating
a bit to T=5600R,
.
2
H O
0.15
ε
±
Fig 4.15 gives
for
o correct for finite
and higher
, use
4.16. Here, for
, there is some significant effect of
w
ε
w
T
P
0,P
1at
→
=
.
m
T
w
P
T
P
w
P L
7.5ftatm
=
w
T
P
P
2
+
. We have
w
T
P
P
12
38.9
25.5atm
2
2
+
+
=
=
way beyond the graph.
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 Fall '05
 ManuelMartinezSanchez
 Propulsion, Heat Transfer, Trigraph, Spacecraft propulsion, Prof. Manuel MartinezSanchez, Propulsion Prof. Manuel, Rocket Propulsion Prof.

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