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MAE 5391: Rocket Propulsion Overview of Propulsion Systems

MAE 5391: Rocket Propulsion Overview of Propulsion Systems. Rocket Technologies. Propulsion Technology Options. Thermodynamic Systems (TE KE) Cold Gas Thrusters Liquids Monopropellants Bipropellants Solids Hybrids Nuclear (NE TE KE) Electric Systems

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MAE 5391: Rocket Propulsion Overview of Propulsion Systems

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  1. MAE 5391: Rocket PropulsionOverview of Propulsion Systems

  2. Rocket Technologies

  3. 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!

  4. Chemical Limitations • Why we have thermo! 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)

  5. Cold Gas Cold Gas: Expand a pressurized gas through a nozzle

  6. Liquid Monopropellant MonoProp: Decompose a single propellant and expand the exhaust through a nozzle 3 N2H4 4 NH3 + N2 + 336,280 joules

  7. Liquid Bi-Propellant BiProp: Combust (burn) two propellants (fuel + oxidizer) in a combustion chamber and expand exhaust through a nozzle Storable Isp 250-320 sec finert=0.03-.13 Cryogenic Isp 320 – 452 sec finert=0.09-0.2 Finert=0.11-0.31 Finert = 0.04-0.2

  8. 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. Advantages Simple Reliable High density Isp No chamber cooling Disadvantages Cracks=disaster Can’t restart Hard to stop Modest Isp Thrust function of burn area, Isp = 250-300 sec Finert=0.06-0.38, 2/3 of motors have fiinert below 0.2

  9. When solids go bad!

  10. Hybrids Load Cell Catalyst Pack Test Stand Fuel Element Combustion Chamber Nozzle Hybrid: Bipropellant system with liquid oxidizer (usually) and a solid fuel Isp= 290-350 sec Finert=0.2 H2O2/PE Hybrid Test Set-Up Polyethylene fuel rod

  11. 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)

  12. Electrothermal-Resistojets 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

  13. 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

  14. 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!

  15. 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

  16. Pulsed Plasma Thrusters Isp = 500-1500 sec P = 1 – 100 W Thrust = 5mN/W

  17. Hall Effect Thruster Power = 50W – 25kW Isp = 500 – 3000 sec Thrust = 5 mN- 1N

  18. 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

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