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02-01-2010, 10:53 PM
send this ppt about rocket engine&their propelants
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Rocket engines
Rocket Engines are reaction engines and obtain thrust in accordance with Newton's third law. A rocket engine is a jet engine that uses only propellant mass for forming its high speed propulsive jet. Most of them are internal combustion engines.
Principle of operation
Rocket engines produce thrust by the expulsion of a high-speed fluid exhaust which is a gas most of the times, created by high pressure (10-200 bar) combustion of solid or liquid propellants, consisting of fuel and oxidiser components in the combustion chamber.
Engine cycles
four different ways of powering the injection of the propellant into the chamber in liquid propellant rockets are:
1)pressure fed cycle in which the propellants are forced in from pressurized heavy tanks
2)expander cycle: the propellants are forced in by turbopumps
3)gas generator cycle: a small percentage of the propellants are burnt in a preburner to power a turbopump and then given out through a separate nozzle.
4)staged combustion cycle: the high pressure outlet from the turbopump is fed back to power a burner which then powers the turbopump in a self starting cycle.
Rocket nozzles
the nozzle chokes and a supersonic jet is formed, dramatically accelerating the gas, converting most of the thermal energy into kinetic energy.A portion of the rocket engine's thrust comes from the unbalanced pressures inside the combustion chamber but the majority comes from the pressures against the inside of the nozzle.
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Rocket Propellants
Rocket propellant is material that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot gas which in turn expand and push on a nozzle, which accelerates them until they rush out of the back of the rocket at extremely high speed, making thrust.
Chemical propellants
There are solid, liquid, and hybrid:
1)Solid propellants:
Solid propellants consist of an oxidizer and a fuel.the standard high-energy solid rocket fuel, Ammonium Perchlorate Composite Propellant (APCP) which is primarily ammonium perchlorate powder as oxidizer, combined with fine aluminium powder as fuel. The mixture is formed as a liquid cast into solid.
2)Liquid propellants:
-LOX and kerosene: is widely regarded as the most practical for civilian orbital launchers.
-LOX and liquid hydrogen, used in the Space Shuttle
-Nitrogen tetroxide (N2O4) and hydrazine (N2H4), MMH, or UDMH
-Monopropellants such as hydrogen peroxide, hydrazine and nitrous oxide
3)Hybrid propellants
A hybrid rocket usually has a solid fuel and a liquid or gas oxidizer. The fluid oxidizer can make it possible to throttle and restart the motor just like a liquid fuelled rocket. Because just one propellant is a fluid, hybrids are simpler than liquid rockets.
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CRYOGENIC ROCKET PROPULSION SYSTEM...I NEED PPT AND THEORY REPORT ON IT...HOPE U SEND THAT TO ME..THANK U