mae 5391: rocket propulsion overview of propulsion systems
TRANSCRIPT
MAE 5391: Rocket PropulsionOverview of Propulsion Systems
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Propulsion Technology Options
Thermodynamic Systems (TE KE) Cold Gas Thrusters Liquids
• Monopropellants• Bipropellants
Solids Hybrids
Nuclear (NE TE KE) Electric Systems
Electrothermal (Resistance Heating) Electrostatic (Ion with E field F=qE) Electromagnetic (plasma with B field F=JxB)
With the exception of electrostatic and electromagnetic, all use concept of gas at some temp flowing though a converging/diverging nozzle!
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Chemical Limitations
Why we have thermo!
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2 /1
0
0
p
p
M
TRV
euexit
Vexit= nozzle exit velocity (m/s)
Ru= universal gas constant (8314.41 J/kmol*K)
T0= chamber temperature (K)
Pe= exit pressure (Pa)
P0= chamber pressure (Pa)
M= molecular mass of gas (kg/kmol)g= ratio of specific heats (no dimensions)
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Cold Gas
Gas MolecularWeight
SpecificImpulse (sec)
Air 28.9 74
Argon 39.9 57
CO2 44.0 67
Helium 4.0 179
Hydrogen 2.0 296
Nitrogen 28.0 80
Methane 16.0 114
1.5 litre X 600 barNitrogen tanks
Fill/drain valve
Two stage regulator (feed pressure ~ 4bar)
Thruster (0.01N,1.3 *10-5 kg/s,throat diameter0.0133 cm)
Stop valve
Microsat cold gaspropulsion systemlayout proposal
Cold Gas: Expand a pressurized gas through a nozzle
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Liquid Monopropellant
Parameter Value
Catalyst LCH 227/202
Steady-state thrust (N) 11.1 - 31.2
Isp (sec) 228 - 235
Propellant specific gravity 1.023
Average Density Isp ( sec) 236.8
Rated total impulse (Nsec) 124,700
Total pulses 12,405
Minimum impulse bit (Nsec) 0.56
Feed pressure (bar) 6.7 - 24.1
Chamber pressure (bar) 4.5 - 12.4
Nozzle expansion ratio 61:1
Mass flow rate (gm/sec) 5.0 - 13.1
Valve power 27 W max @ 28 VDC
Thruster mass (kg) 0.52
3 N2H4 4 NH3 + N2 + 336,280 joules
MonoProp: Decompose a single propellant and expand the exhaust through a nozzle
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Liquid Bi-Propellant
Storable Isp 250-320 sec
finert=0.03-.13
Cryogenic Isp 320 – 452 sec
finert=0.09-0.2
BiProp: Combust (burn) two propellants (fuel + oxidizer) in a combustion chamber and expand exhaust through a nozzle
Finert = 0.04-0.2 Finert=0.11-0.31
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Solids
Composite propellant, consisting of an oxidizing agent, such as ammonium nitrate or ammonium perchlorate intimately mixed with an organic or metallic fuel and binder.
Thrust function of burn area, Isp = 250-300 sec
Finert=0.06-0.38, 2/3 of motors have fiinert below 0.2
AdvantagesSimpleReliableHigh density IspNo chamber cooling
DisadvantagesCracks=disasterCan’t restartHard to stopModest Isp
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When solids go bad!
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Hybrids
Isp= 290-350 sec
Finert=0.2
Hybrid: Bipropellant system with liquid oxidizer (usually) and a solid fuel
Catalyst Pack
Combustion Chamber
Nozzle
Test Stand
Load Cell
Fuel Element
H2O2/PE Hybrid Test Set-Up
Polyethylene fuel rod
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Nuclear Thermal Propulsion
NERVA Program Thrust = 890,000N Isp = 838 sec Working fluid = Hydrogen Test time = 30 minutes Stopped in 1972 Finert=0.5-0.7 (shielding)
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Electrothermal-Resistojets
Nozzle
Thermocouple tapping
Stainless steel outer1225W Cartridge heater
Water inlet
Heater thermocouple
Power inputSintered stainlesswater distribution ring
Sintered stainless filterPressure tapping
SiC Heat transfer medium
Cutaway of Mark- III Resistojet
Working Fluid
Thrust (mN) Isp (sec) Power (W) Cp (kJ/kg K) Tc (K)
hydrogen 37 546 100 14.32 1000
water 93 219 100 2.3 1000
nitrous oxide 141 144 100 1.0 1000
Electrothermal-- electrical energy is used to directly heat a working fluid. The resulting hot gas is then expanded through a converging-diverging nozzle to achieve high exhaust
velocities. These systems convert thermal energy to kinetic energy
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Electrothermal-Arcjets
In an arcjet, the working gas is injected in a chamber through which an electric arc is struck. The gas is heated to very high temperature (3000 – 4000 K), Arc temp =10,000K on average, and much greater in certain regions in the arc.
Power = 1.8 kW, Isp = 502, Thrust = 0.2N, Propellant = hydrazine
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Electrostatic-Ion Propulsion
Electrostatic-- electrical energy is directly converted into kinetic energy. Electrostatic forces are applied to charged particles to accelerate the propellant.
Deep Space 1 = 4.2 kW, Thrust = 165 mN, Isp = 3800 sec
7000 hours of operation is becoming the standard!
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Electromagnetic-MPD Thruster
Electromagnetic-- electromagnetic forces directly accelerate the reaction mass. This is done by the interaction of electric and magnetic fields on a highly ionised propellant plasma.
NH3 MPD, F=23 mN, Isp= 600 sec, P=430 W
Stuttgart, Isp=5000sec, F=100N, P=6 MW, hydrogen
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Pulsed Plasma Thrusters
Ctrigger
CMain
Rtrigger
CenterElectrode
IntermediateElectrode
OuterElectrode
Teflon Annulus
PPUSpacecraft
Ground
Isp = 500-1500 sec
P = 1 – 100 W
Thrust = 5mN/W
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Hall Effect Thruster
Power = 50W – 25kW
Isp = 500 – 3000 sec
Thrust = 5 mN- 1N
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Propulsion System “Cost”
Performance issues Mass Volume Time (thrust) Power Safety Logistics Integration Technical Risk
The “best” (lowest “cost”) option optimizes these issues for a given set of mission requirements