Propulsion Systems Design
•
•
•
•
•
•
Lecture #18 - October 30, 2014
Crew Systems/PPT Systems Project
Rocket engine basics
Survey of the technologies
Propellant feed systems
Propulsion systems design
© 2014 David L. Akin - All rights reserved
http://spacecraft.ssl.umd.edu
UNIVERSITY OF
MARYLAND
1
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Notes:
• I will be posting separately (later today) details on
the third team project (Crew Systems/Power,
Propulsion, and Thermal Systems) and the next
problem set
• From here on out, a single problem set will be
issued for each of the disciplinary lecture sets (CS,
PPT, LSM, AVS)
• Today at 3:30 in AVW 2116, the guest speaker in
ENAE 788X will be Robert Giglio, chief rover
designer for Astrobotic
UNIVERSITY OF
MARYLAND
2
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Propulsion Taxonomy
Mass Expulsion
Non-Mass Expulsion
Thermal
Non-Thermal
Chemical
Non-Chemical
Ion
MPD
Monopropellants
Nuclear
Bipropellants
Beamed
Electrical
Solar Sail
Laser Sail
Microwave Sail
Cold Gas
Solar
Solids
Hybrids
Pressure-Fed
Liquids
ED Tether
Pump-Fed
UNIVERSITY OF
MARYLAND
Air-Breathing
MagnetoPlasma
3
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Thermal Rocket Exhaust Velocity
• Exhaust velocity is
γ −1 .
+
2γ ℜT0 - %' pe (* γ 0
Ve =
-1− ' * 0
γ −1 M - & p0 ) 0
,
/
!
!
!
where
M ≡ average molecular weight of exhaust
Joules
ℜ ≡ universal gas const.= 8314.3
mole°K
γ ≡ ratio of specific heats ≈ 1.2
UNIVERSITY OF
MARYLAND
4
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Ideal Thermal Rocket Exhaust Velocity
• Ideal exhaust velocity is
2γ ℜT0
!
Ve =
γ −1 M
!
• This corresponds to an ideally expanded nozzle
• All thermal energy converted to kinetic energy of
exhaust
• Only a function of temperature and molecular
weight!
UNIVERSITY OF
MARYLAND
5
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Thermal Rocket Performance
• Thrust is
T = m˙ Ve + ( pe − pamb) Ae
!
• Effective exhaust velocity
Ae
T = m˙ c ⇒ c = Ve + ( pe − pamb)
!
m˙
• Expansion ratio
!
At # γ + 1&
=%
(
Ae $ 2 '
1
γ −1
UNIVERSITY OF
MARYLAND
6
#p &
%% e ((
$ p0 '
1
γ
"
%
c
$$ Is p = ''
g0 &
#
γ −1 *
γ + 1 , #% pe &( γ /
,1− % ( /
γ −1 , $ p0 ' /
+
.
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
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
=
and T = ṁVe then Isp = Ve !!!
ṁ
UNIVERSITY OF
MARYLAND
7
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
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
!
γ −1
γ
#p &
= 1− %% e ((
!
Ve,ideal
$ p0 '
• Isp,vacuum=455 sec --> Isp,sl=333 sec
!
Ve
UNIVERSITY OF
MARYLAND
8
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Solid Rocket Motor
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
9
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Solid Propellant Combustion Characteristics
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
10
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Solid Grain Configurations
From G. P. Sutton, Rocket Propulsion Elements
(5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
11
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Short-Grain Solid Configurations
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John
Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
12
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Advanced Grain Configurations
From G. P. Sutton, Rocket Propulsion Elements
(5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
13
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Liquid Rocket Engine
UNIVERSITY OF
MARYLAND
14
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Liquid Propellant Feed Systems
UNIVERSITY OF
MARYLAND
15
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Space Shuttle OMS Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 2001
UNIVERSITY OF
MARYLAND
16
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Turbopump Fed Liquid Rocket Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
17
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Sample Pump-fed Engine Cycles
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
18
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Gas Generator Cycle Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
19
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
SSME Powerhead Configuration
UNIVERSITY OF
MARYLAND
20
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
SSME Engine Cycle
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 2001
UNIVERSITY OF
MARYLAND
21
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Liquid Rocket Engine Cutaway
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 2001
UNIVERSITY OF
MARYLAND
22
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
H-1 Engine Injector Plate
UNIVERSITY OF
MARYLAND
23
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Injector Concepts
From G. P. Sutton, Rocket Propulsion Elements (5th ed.)
John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
24
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
TR-201 Engine (LM Descent/Delta)
UNIVERSITY OF
MARYLAND
25
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Solid Rocket Nozzle (Heat-Sink)
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
26
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Ablative Nozzle Schematic
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
27
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Active Chamber Cooling Schematic
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
28
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Boundary Layer Cooling Approaches
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
29
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Hybrid Rocket Schematic
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
30
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Hybrid Rocket Combustion
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
31
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Thrust Vector Control Approaches
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
32
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
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
UNIVERSITY OF
MARYLAND
33
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Single-Axis Equations of Motion
⌧ = I ✓¨
⌧
t = ✓˙ + C1
I
⌧
˙
˙
at t = 0, ✓ = ✓o =) t = ✓˙ ✓˙o
I
1⌧ 2
t + ✓˙o t = ✓ + C2
2I
1⌧ 2
at t = 0, ✓ = ✓o =)
t + ✓˙o t = ✓ ✓o
2I
⇣
⌘
2
1 ˙2
⌧
˙
✓
✓o = (✓ ✓o )
2
I
UNIVERSITY OF
MARYLAND
34
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Attitude Trajectories in the Phase Plane
3.00%
2.00%
1.00%
!20.00%
!10.00%
0.00%
0.00%
10.00%
20.00%
30.00%
40.00%
tau/I=0%
!1.00%
!0.001%
!0.002%
!2.00%
!0.003%
!0.004%
!3.00%
UNIVERSITY OF
MARYLAND
35
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Gemini Entry Reaction Control System
UNIVERSITY OF
MARYLAND
36
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Apollo Reaction Control System
UNIVERSITY OF
MARYLAND
37
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Apollo CSM RCS Assembly
UNIVERSITY OF
MARYLAND
38
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Lunar Module Reaction Control System
UNIVERSITY OF
MARYLAND
39
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
LM RCS Quad
UNIVERSITY OF
MARYLAND
40
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Viking Aeroshell RCS Thruster
UNIVERSITY OF
MARYLAND
41
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Space Shuttle Primary RCS Engine
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
42
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Monopropellant Engine Design
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
43
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Cold Gas Thruster Exhaust Velocity
Assume nitrogen gas thrusters
v
"
u
✓ ◆
u 2 <T0
pe
t
Ve =
1
1 M̄
po
M̄ = 28
T0 = 300 K
< = 8314.3
MARYLAND
44
#
p0 = 300 psi
pe = 2 psi
= 1.4
v
"
u
u 2(1.4) 8314.3(300)
Ve = t
1
1.4 1
28
UNIVERSITY OF
1
✓
2
300
◆ 1.41.4 1 #
m
= 689
sec
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Cold-gas Propellant Performance
From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986
UNIVERSITY OF
MARYLAND
45
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Total Impulse
• Total impulse It is the total thrust-time product for
the propulsion system, with units <N-sec>
!
It = T t = ṁve t
!
⇢V
t=
ṁ
It = ⇢V ve
!
!
• To assess cold-gas systems, we can examine total
impulse per unit volume of propellant storage
It
= ⇢ve
V
UNIVERSITY OF
MARYLAND
46
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Performance of Cold-Gas Systems
UNIVERSITY OF
MARYLAND
47
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Self-Pressurizing Propellants (CO2)
UNIVERSITY OF
MARYLAND
48
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Self-Pressurizing Propellants (N2O)
Density!
1300 kg/m3
UNIVERSITY OF
MARYLAND
49
Density!
625 kg/m3
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
N2O Performance Augmentation
• Nominal cold-gas exhaust velocity ~600 m/sec
• N2O dissociates in the presence of a heated
2N2 O ! 2N2 + O2
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
UNIVERSITY OF
MARYLAND
50
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Pressurization System Analysis
Adiabatic Expansion of Pressurizing Gas
Pg0, Vg
Pgf, Vg
γ
g, 0 g
γ
g
p V = pg, f V + pl Vl
γ
Known quantities:
Pg,0=Initial gas pressure
PL, VL
Initial
PL, VL
Pg,f=Final gas pressure
PL=Operating pressure of propellant
Final
tank(s)
VL=Volume of propellant tank(s)
Solve for gas volume Vg
UNIVERSITY OF
MARYLAND
51
Propulsion Systems Design
!
ENAE 483/788D - Principles of Space Systems Design
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
UNIVERSITY OF
MARYLAND
52
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
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
1.67
g
!(4500 psi )V
1.67
g
= ( 388 psi)V
+ (312 psi)(17.39 m
• Vg = 3.713 m3
• Ideal gas:
T=300°K --> ρHe =
ρ=49.7 kg/m3 (4500 psi = 31.04 MPa) MHe=185.1 kg
UNIVERSITY OF
MARYLAND
53
3 1.67
)
pg, 0 M
ℜT0
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Nuclear Thermal Rockets
• Heat propellants by passing
through nuclear reactor
• Isp limited by temperature
limits on reactor elements
(~900 sec for H2 propellant)
• Mass impacts of reactor,
shielding
• High thrust system
UNIVERSITY OF
MARYLAND
54
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
VASIMR Engine Concept
UNIVERSITY OF
MARYLAND
55
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Ion Propulsion
• Uses electrostatic forces to
accelerate ions
• Injects electrons to keep
beam neutral
• High Isp (~3000 sec) at low
thrust (~10 N)
• Substantial mass penalty for
electrical power generation
UNIVERSITY OF
MARYLAND
56
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Solar Sails
• Sunlight reflecting off sail
produces momentum transfer
!
˙c
T = 2m˙ V = 2 m
!
E
E 1 P
2
E = mc
⇒ m = 2 ⇒ m˙ =
2 = 2
!
c
t c
c
!
• At 1 AU, P=1394 W/m2
• c=3x108 m/sec
• T=9x10-6 N/m2
UNIVERSITY OF
MARYLAND
57
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design
Propulsion Taxonomy
Mass Expulsion
Non-Mass Expulsion
Thermal
Non-Thermal
Chemical
Non-Chemical
Ion
MPD
Monopropellants
Nuclear
Bipropellants
Beamed
Electrical
Solar Sail
Laser Sail
Microwave Sail
Cold Gas
Solar
Solids
Hybrids
Pressure-Fed
Liquids
ED Tether
Pump-Fed
UNIVERSITY OF
MARYLAND
Air-Breathing
MagnetoPlasma
58
Propulsion Systems Design
ENAE 483/788D - Principles of Space Systems Design