me 814.3 t2: compressible flow instructor: maryam einian email:...
TRANSCRIPT
Tests1. Discharge of compressed air from a tank
2. Flow through a converging-diverging nozzle
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Discharge of compressed air from a tank
Fill the tankDischarge the tank
Observe the pressure and temperature variation in time
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Formulation Quasi-steady process:
Ktp
p
i
2
11
2
1
1
2
2
1 1
1
i
r
n RT
V
AK
unsteady continuity
steady energy equation
Converging-Diverging nozzle
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Application: Propulsion and the High speed flow of gases.
Mass Flow Rate:
Low Pressure at the back
?More mass flow rate
Subsonic Flow (M<1)
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1- Nozzle isn't choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat.
5- Lowering the back pressure increases the flow speed everywhere in the nozzle.
4- Decelerates through the diverging section.
Sonic Flow (M=1)
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1- Nozzle is choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat. (M=1)
4- Decelerates through the diverging section.
Supersonic Flow (M>1)
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1- Nozzle is choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat.
4- Accelerates through the diverging section.
Shock Wave
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1- Nozzle is choked
2- Accelerates through the converging section
3- Reaches its maximum speed at the throat.
4- Accelerates through the diverging section.
5- Shock wave occurs.
6- Decelerates through the diverging section.
Conservation
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constantVA
constant2
1 2 Vh
constant2
1)( 2 Vp
u
Conservation of mass
Conservation of energy
Conservation of momentum
Isentropic Flow
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12
2
11
M
p
po
1
T
T
p
p oo
A perfect gas2
2
11 M
T
To
12
1
2
*
121
121
11
M
MA
A
Shock Wave
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Highly irreversible No isentropic process
12
212
1
212
2
M
MM
22
21
1
2
1
1
M
M
P
P
)1(2
1
22
21
2
1
1
2
)1(2
)1(2
M
M
M
M
P
P
o
o
1
2
2
1
*
*
o
o
P
P
A
A
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o
ok
k
o
k
o RT
AP
P
P
P
P
k
km
12.
11
2
Mass Flow Rate
o
ok
k
RT
PA
kkm
*)1(2
1
21max
.
1
2
ObjectivesTo obtain the pressure distribution along a
converging-diverging nozzle.
To compare the experimental results with the theoretical calculations.
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Supersonic Shock wave Subsonic
Pos =; Ptank =,
Pb =; To =
Pos =; Ptank =,
Pb =; To =
Pos =; Ptank =,
Pb =; To =
x Pressure, Ps x Pressure, Ps x Pressure, Ps
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Data Acquisition
What Do We Require To Obtain From The Raw Data?
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max
..
, ,*
, mmA
A
P
P
o
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Dimensions of Converging-Diverging Nozzle
A Summary of Important Quantities
R 12.70 mm 0.500 in
Dt 14.78 mm 0.582 in
Dprobe 1.50 mm 0.059 in
Patm To be measured
k 1.40 1.40
Rair 287 J/KgK 1717 ft2/s2oR18
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