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MAE 5391: Rocket Propulsion Overview of Propulsion Systems.

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Presentation on theme: "MAE 5391: Rocket Propulsion Overview of Propulsion Systems."— Presentation transcript:

1 MAE 5391: Rocket Propulsion Overview of Propulsion Systems

2 2 Rocket Technologies

3 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 4 Chemical Limitations  Why we have thermo! V exit = nozzle exit velocity (m/s) R u = universal gas constant ( J/kmol*K) T 0 = chamber temperature (K) P e = exit pressure (Pa) P 0 = chamber pressure (Pa) M= molecular mass of gas (kg/kmol)  = ratio of specific heats (no dimensions)

5 5 Cold Gas GasMolecular Weight Specific Impulse (sec) Air Argon CO Helium Hydrogen Nitrogen Methane Cold Gas: Expand a pressurized gas through a nozzle

6 6 Liquid Monopropellant ParameterValue CatalystLCH 227/202 Steady-state thrust (N) Isp (sec) Propellant specific gravity1.023 Average Density Isp ( sec)236.8 Rated total impulse (Nsec)124,700 Total pulses12,405 Minimum impulse bit (Nsec)0.56 Feed pressure (bar) Chamber pressure (bar) Nozzle expansion ratio61:1 Mass flow rate (gm/sec) Valve power27 W 28 VDC Thruster mass (kg) N 2 H 4  4 NH 3 + N ,280 joules MonoProp: Decompose a single propellant and expand the exhaust through a nozzle

7 7 Liquid Bi-Propellant StorableIsp sec finert= Cryogenic Isp 320 – 452 sec finert= BiProp: Combust (burn) two propellants (fuel + oxidizer) in a combustion chamber and expand exhaust through a nozzle Finert = Finert=

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

9 9 When solids go bad!

10 10 Hybrids Isp= 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 H 2 O 2 /PE Hybrid Test Set-Up Polyethylene fuel rod

11 11 Nuclear Thermal Propulsion NERVA Program  Thrust = 890,000N  Isp = 838 sec  Working fluid = Hydrogen  Test time = 30 minutes  Stopped in 1972  Finert= (shielding)

12 12 Electrothermal-Resistojets Working Fluid Thrust (mN)Isp (sec)Power (W)Cp (kJ/kg K)Tc (K) hydrogen water nitrous oxide 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 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 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 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. NH 3 MPD, F=23 mN, Isp= 600 sec, P=430 W Stuttgart, Isp=5000sec, F=100N, P=6 MW, hydrogen

16 16 Pulsed Plasma Thrusters Isp = sec P = 1 – 100 W Thrust = 5  N/W

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

18 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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