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Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Propulsion and Power Systems Design• Rocket engine basics • Survey of the technologies • Propellant feed systems • Propulsion systems design • Energy storage devices
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© 2020 David L. Akin - All rights reserved http://spacecraft.ssl.umd.edu
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Liquid Rocket Engine Cutaway
2
Propulsion and Power Systems Design 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
3
Propulsion and Power Systems Design 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
4
Propulsion and Power Systems Design 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
"
# $ $
%
& ' '
5
Propulsion and Power Systems Design 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!!!
6
Propulsion and Power Systems Design 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
7
Propulsion and Power Systems Design 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
8
Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Advanced Grain ConfigurationsFrom G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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
16
Propulsion and Power Systems Design 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
17
Propulsion and Power Systems Design 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
18
Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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
25
Propulsion and Power Systems Design 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
26
Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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
28
Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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
30
Propulsion and Power Systems Design 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
31
Propulsion and Power Systems Design 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
32
Propulsion and Power Systems Design 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
33
Propulsion and Power Systems Design 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
34
Propulsion and Power Systems Design 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
35
Propulsion and Power Systems Design 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
36
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Reaction Control Systems• Thruster control of vehicle attitude and translation • “Bang-bang” control algorithms • Design goals:
– Minimize coupling (pure forces for translation; pure moments for rotation)except for pure entry vehicles
– Minimize duty cycle (use propellant as sparingly as possible)
– Meet requirements for maximum rotational and linear accelerations
37
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Single-Axis Equations of Motion
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⌧ = I ✓
⌧
It = ✓ + C1
at t = 0, ✓ = ✓o =) ⌧
It = ✓ � ✓o
at t = 0, ✓ = ✓o =) 1
2
⌧
It2 + ✓ot = ✓ � ✓o
1
2
⌧
It2 + ✓ot = ✓ + C2
1
2
⇣✓2 � ✓o
2⌘=
⌧
I(✓ � ✓o)
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Attitude Trajectories in the Phase Plane
39
!3.00%
!2.00%
!1.00%
0.00%
1.00%
2.00%
3.00%
!20.00% !10.00% 0.00% 10.00% 20.00% 30.00% 40.00%
tau/I=0%
!0.001%
!0.002%
!0.003%
!0.004%
Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
RCS Quad
42
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Apollo CSM RCS Assembly
43
Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design 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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Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Viking RCS Thruster Schematic
47
Propulsion and Power Systems Design 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
48
Propulsion and Power Systems Design 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
49
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Cold Gas Thruster Exhaust Velocity
50
Ve =
vuut 2�
� � 1
<T0
M
"1�
✓pepo
◆ ��1�
#
Ve =
vuut 2(1.4)
1.4� 1
8314.3(300)
28
"1�
✓2
300
◆ 1.4�11.4
#= 689
m
sec
Assume nitrogen gas thrusters
M = 28
T0 = 300 K
p0 = 300 psi
pe = 2 psi
� = 1.4< = 8314.3
Propulsion and Power Systems Design 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
51
Propulsion and Power Systems Design 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
52
It = Tt = mvet
t =⇢V
m
It = ⇢V ve
ItV
= ⇢ve
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Performance of Cold-Gas Systems
53
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Self-Pressurizing Propellants (CO2)
54
Propulsion and Power Systems Design 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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Density1300 kg/m3
Density625 kg/m3
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
N2O Performance Augmentation• Nominal cold-gas exhaust velocity ~600 m/sec • N2O dissociates in the presence of a heated
catalyst engine temperature ~1300°C exhaust velocity ~1800 m/sec
• NOFB (Nitrous Oxide Fuel Blend) - store premixed N2O/hydrocarbon mixture exhaust velocity >3000 m/sec
56
2N2O �! 2N2 +O2
Propulsion and Power Systems Design 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
57
Propulsion and Power Systems Design 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 m
58
Propulsion and Power Systems Design 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
€
4500 psi( )Vg1.67 = 388 psi( )Vg
1.67 + 312 psi( ) 17.39 m 3( )1.67
€
ρHe =pg,0M ℜT0
59
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Autogenous Pressurization• Use gaseous propellants to pressurize tanks with
liquid propellants • Heat exchanger to gasify and warm propellants,
then route back into ullage volume • Eliminates need for pressurized gases for ullage
and high-pressure storage bottles (e.g., Falcon 9 failures)
• Issue: start-up transient
60
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Energy and Power - Not the Same!!!• Energy - the capacity of a physical system to do
work (J, N-m, kWhr) • Power - time rate of change of energy (W, N-m/
sec, J/sec) • We are interested in generating power; we store and
use energy at a given power level.
61
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Batteries• Energy storage via chemical reactions • Primary batteries - use once and discard • Secondary batteries - rechargable • Critical parameters
– Energy density – Discharge rate – Allowable depth of discharge – Cycle life – Temperature limits
62
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Primary Batteries
63
From Pisacane and Moore, Fundamentals of Space Systems Oxford University Press, 1994
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Battery Application Domains
64
From Wertz, Everett, and Puschell, Space Mission Engineering: The New SMAD Microcosm Press, 2011
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
Integrated Vehicle Fluids (IVF) System
65
From M. Holguin, “Enabling Long Duration Spaceflight via an Integrated Vehicle Fluid System” AIAA 2016-5495
Propulsion and Power Systems Design ENAE 791 - Launch and Entry Vehicle Design
U N I V E R S I T Y O FMARYLAND
ULA IVF Concept• 750cc internal combustion (piston) engine
powered by LOX/LH2 boil-off • Engine powers generator to supply electrical
power (30V and 300V) to vehicle (also serves as a starter)
• Compressor/heat exchanger increases pressure of boil-off gases from propellant tank, and cools ICE
• Pressurized O2/H2 provides reaction control system through thruster/gimbal assembly
• Growth option: on-orbit refueling
66
