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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Propulsion Systems Design• Rocket engine basics • Survey of the technologies • Propellant feed systems • Propulsion systems design
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© 2016 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu
Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Liquid Rocket Engine Cutaway
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Thermal Rocket Exhaust Velocity• Exhaust velocity is !
!
!
where
€
Ve =2γγ −1
ℜT0M
1− pe
p0
%
& ' '
(
) * *
γ −1γ
+
,
- - -
.
/
0 0 0
€
M ≡ average molecular weight of exhaust
€
ℜ ≡ universal gas const .= 8314.3 Joulesmole°K
€
γ ≡ ratio of specific heats ≈1.2
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Ideal Thermal Rocket Exhaust Velocity• Ideal exhaust velocity is !
!• This corresponds to an ideally expanded nozzle • All thermal energy converted to kinetic energy
of exhaust • Only a function of temperature and molecular
weight!
€
Ve =2γγ −1
ℜT0M
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Thermal Rocket Performance• Thrust is !
• Effective exhaust velocity !!
• Expansion ratio
€
T = ˙ m Ve + pe − pamb( )Ae
€
T = ˙ m c ⇒ c = Ve + pe − pamb( ) Ae
˙ m
€
AtAe
=γ +12
#
$ %
&
' (
1γ −1 pe
p0
#
$ % %
&
' ( (
1γ γ +1
γ −11−
pep0
#
$ % %
&
' ( (
γ −1γ
*
+
, , ,
-
.
/ / /
€
Isp =cg0
"
# $ $
%
& ' '
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
A Word About Specific Impulse• Defined as “thrust/propellant used”
– English units: lbs thrust/(lbs prop/sec)=sec – Metric units: N thrust/(kg prop/sec)=m/sec
• Two ways to regard discrepancy - – “lbs” is not mass in English units - should be slugs – Isp = “thrust/weight flow rate of propellant”
• If the real intent of specific impulse is
Isp =T
mand T = mVe then Isp = Ve!!!
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Nozzle Design
• Pressure ratio p0/pe=100 (1470 psi-->14.7 psi)Ae/At=11.9
• Pressure ratio p0/pe=1000 (1470 psi-->1.47 psi)Ae/At=71.6
• Difference between sea level and ideal vacuum Ve
!!!
• Isp,vacuum=455 sec --> Isp,sl=333 sec
€
VeVe,ideal
= 1− pep0
#
$ % %
&
' ( (
γ −1γ
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Solid Rocket Motor
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Solid Propellant Combustion Characteristics
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Solid Grain Configurations
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Short-Grain Solid Configurations
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Gemini Retrograde Engine
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Advanced Grain Configurations
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Liquid Rocket Engine
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Liquid Propellant Feed Systems
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Space Shuttle OMS Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Turbopump Fed Liquid Rocket Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Sample Pump-fed Engine Cycles
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Gas Generator Engine Schematic
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
SpaceX Merlin 1d Engines
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Falcon 9 Octoweb Engine Mount
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Staged-Combustion Engine Schematic
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
RD-180 Engine(s) (Atlas V)
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
SSME Powerhead Configuration
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
SSME Engine Cycle
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Liquid Rocket Engine Cutaway
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
H-1 Engine Injector Plate
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Injector Concepts
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
TR-201 Engine (LM Descent/Delta)
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Solid Rocket Nozzle (Heat-Sink)
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Ablative Nozzle Schematic
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Active Chamber Cooling Schematic
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Boundary Layer Cooling Approaches
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Hybrid Rocket Schematic
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Hybrid Rocket Combustion
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Thrust Vector Control Approaches
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Gemini Entry Reaction Control System
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Apollo Reaction Control System Thrusters
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
RCS Quad
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Apollo CSM RCS Assembly
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Lunar Module Reaction Control System
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
LM RCS Quad
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Viking Aeroshell RCS Thruster
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Viking RCS Thruster Schematic
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Space Shuttle Primary RCS Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Monopropellant Engine Design
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Cold-gas Propellant Performance
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Total Impulse• Total impulse It is the total thrust-time product for
the propulsion system, with units <N-sec> !
!
!
!
• To assess cold-gas systems, we can examine total impulse per unit volume of propellant storage
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It = Tt = mvet
t =⇢V
m
It = ⇢V ve
ItV
= ⇢ve
Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Performance of Cold-Gas Systems
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Self-Pressurizing Propellants (CO2)
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Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Self-Pressurizing Propellants (N2O)
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Density!1300 kg/m3
Density!625 kg/m3
Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
N2O Performance Augmentation
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• Nominal cold-gas exhaust velocity ~600 m/sec • N2O dissociates in the presence of a heated catalyst
engine temperature ~1300°Cexhaust velocity ~1800 m/sec
• NOFB (Nitrous Oxide Fuel Blend) - store premixed N2O/hydrocarbon mixtureexhaust velocity >3000 m/sec
2N2O �! 2N2 +O2
Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Pressurization System Analysis
Pg0, Vg
PL, VL
Pgf, Vg
PL, VL
Adiabatic Expansion of Pressurizing Gas
Initial Final
€
pg,0Vgγ = pg, fVg
γ + plVlγ
Known quantities:
Pg,0=Initial gas pressure
Pg,f=Final gas pressure
PL=Operating pressure of propellant tank(s)
VL=Volume of propellant tank(s)
Solve for gas volume Vg
!53
Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Boost Module Propellant Tanks• Gross mass 23,000 kg
– Inert mass 2300 kg – Propellant mass 20,700 kg – Mixture ratio N2O4/A50 = 1.8 (by mass)
• N2O4 tank – Mass = 13,310 kg – Density = 1450 kg/m3
– Volume = 9.177 m3 --> rsphere=1.299 m • Aerozine 50 tank
– Mass = 7390 kg – Density = 900 kg/m3
– Volume = 8.214 m3 --> rsphere=1.252 m54
Rocket Propulsion ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Boost Module Main Propulsion• Total propellant volume VL = 17.39 m3
• Assume engine pressure p0 = 250 psi • Tank pressure pL = 1.25*p0 = 312 psi • Final GHe pressure pg,f = 75 psi + pL = 388 psi • Initial GHe pressure pg,0 = 4500 psi • Conversion factor 1 psi = 6892 Pa • Ratio of specific heats for He = 1.67 !
• Vg = 3.713 m3 • Ideal gas: T=300°K --> ρ=49.7 kg/m3 (4500 psi = 31.04 MPa) MHe=185.1 kg
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4500 psi( )Vg1.67 = 388 psi( )Vg
1.67 + 312 psi( ) 17.39 m 3( )1.67
€
ρHe =pg,0M ℜT0
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