Mechanical Engineering Project: Rocket Fuels
11 likes2,683 views
The document provides an overview of rocket propulsion systems, focusing on chemical, electrical, and advanced methods of propulsion. It details solid rocket motors, including their advantages, disadvantages, components, and types of propellants and oxidizers used. Additionally, it highlights the design considerations for solid rocket components, such as the thermal insulation and ignition systems.
Mechanical Engineering Project: Rocket Fuels
- 2. What Is Propulsion? • Initiating or changing the motion of a body – Translational (linear, moving faster or slower) – Rotational (turning about an axis) • Space propulsion – Rocket launches – Controlling satellite motion – Maneuvering spacecraft • Jet propulsion – Using the momentum of ejected mass (propellant) to create a reaction force, inducing motion At one time it was believed that rockets could not work in a vacuum -- they needed air to push against!!
- 3. Space Propulsion System Classifications Stored Gas Chemical Electric Advanced • Electrothermal • Electrostatic • Electrodynamic • Nuclear • Solar thermal • Laser • Antimatter LiquidSolid Hybrid Pump FedPressure Fed MonopropellantBipropellant Space propulsion systems are classified by the type of energy source used.
- 4. Solid Rocket Motors • A solid rocket motor is a system that uses solid propellants to produce thrust • Advantages – High thrust – Simple – Storability – High density Isp • Disadvantages – Low Isp (compared to liquids) – Complex throttling – Difficult to stop and restart – Safety
- 5. Solid Rocket Motors • Solid rocket motors are used for – Launch vehicles • High thrust (high F/W ratio) • High storage density – Ballistic Missiles • Propellant storability • Excellent aging • Quick response – storability – high F/W ratio)
- 6. 6 SOLID PROPELLANT ROCKETS • Solid fuel rockets rely on controlled explosion of a mixture of substances • Nearly a homogeneous material that is burned • Similar to gunpowder ~ (75% potassium nitrate, 10% carbon, and 15% sulfur) • Example: STS Solid Rocket Boosters: – Contain ammonium perchlorate as an oxidizer and aluminum as a fuel – Rest of mixture devoted to bonding two reactants – Once a solid rocket is ignited, can not be turned off
- 7. 7 OVERVIEW: SOLID ROCKET COMPONENTS
- 8. 8 MINUTEMAN SOLID ROCKET Minuteman first stage motor Minuteman missile systems, operated by Air Force Combat Command are long-range, solid-fuel, three-stage intercontinental ballistic missiles capable of carrying single or multiple nuclear warheads. The program began in 1958 and is one of Boeing's longest military contracts.
- 9. Solid Rocket Motor Components
- 10. Thermal Insulation • Design involves: – Analysis of combustion chamber environment • Stagnation temperature • Stagnation pressure • Propellant gases (material compatibility) – Selection of insulation material – Material thickness determination for various areas of the motor case – For the cylindrical part of the case, the walls are only exposed to hot combustion gases at the end of the burn
- 11. The Nozzle • The design of the nozzle follows similar steps as for other thermodynamic rockets – Throat area determined by desired stagnation pressure and thrust level – Expansion ratio determined by ambient pressure or pressure range to allow maximum efficiency • Major difference for solid propellant nozzles is the technique used for cooling – Ablation – Fiber reinforced material used in and near the nozzle throat (carbon, graphite, silica, phenolic)
- 12. Ablation • Meteorite – Re-entry speed of 10 - 20 km/sec – Extreme heating in the atmosphere – Ablation and internal energy modes cooled the meteorite through its fall • Ablation gas cloud • Dissociation • Internal energy deposition – Stony-Iron Classification • (95% of all meteorites)
- 13. Ignition System • Large solid motors typically use a three-stage ignition system – Initiator: Pyrotechnic element that converts electrical impulse into a chemical reaction (primer) – Booster charge – Main charge: A charge (usually a small solid motor) that ignites the propellant grain. Burns for tenths of a second with a mass flow about 1/10 of the initial propellant grain mass flow.
- 14. Propellant Grain • Two main categories – Double Base: A homogeneous propellant grain, usually nitrocellulose dissolved in nitroglycerin. Both ingredients are explosive and act as a combined fuel, oxidizer and binder – Composite: A heterogeneous propellant grain with oxidizer crystals and powdered fuel held together in a matrix of synthetic rubber binder. • Less hazardous to manufacture and handle
- 15. Conventional Composite • Fuel – 5-20% Powdered Aluminum • Oxidizer – 65-72% Ammonium Perchlorate (NH4ClO4 or AP) • Binder – 8-14% Hydroxyl- Terminated Polybutadiene (HTPB)
- 16. Fuels • Aluminum (Al) – Molecular Weight: 26.98 kg/kmol – Density: 2700 kg/m3 – Most commonly used • Magnesium (Mg) – Molecular Weight: 24.32 kg/kmol – Density: 1750 kg/m3 – Clean burning (green) • Beryllium (Be) – Molecular Weight: 9.01 kg/kmol – Density: 2300 kg/m3 – Most energetic, but extremely toxic exhaust products
- 17. Oxidizers • Ammonium Perchlorate (AP) – Most commonly used – Cl combining with H can form HCl • Toxic • Depletion of ozone • Ammonium Nitrate (AN) – Next most commonly used – Less expensive than AP – Less energetic – No hazardous exhaust products
- 18. Binders • Hydroxyl Terminated Polybutadiene (HTPB) – Most commonly used – Consistency of tire rubber • Polybutadiene Acrylonitrile (PBAN) • Nitrocellulose (PNC) – Double base agent
- 19. Additives • Used to promote – Curing – Enhanced burn rate (HMX) – Bonding – Reduced radiation through the grain (darkening) – Satisfactory aging – Reduced cracking
- 20. FOR COMPLETE PRESENTATION, MORE PROJECTS PRESENTATIONS AND PROJECT REPORTS VISIT WWW.MECHIEPROJECTS.COM Email: contactus@mechieprojects.com THANKYOU
- 21. This is purely an academic work and has no financial or other interest. The results achieved in this should be independently verified.