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03-07-2010, 08:06 PM
Myself Roshan and i am a B tech student in CUSAT India. I am planing to take a seminar and presentation on Cryogenic Engines.I am posting the topics i am intending to take for my seminar and presentation.
1. Introduction to cryogenic Engines
2. Types of Cryogenic Engines
3. Fuels Used in Cryogenic Engines
4. Types of Injectors used
I will be obliged to you sir if i can get details about all these. No need for made presentations as i like to prepare myself. Please pass me the necessory details to make a 30 min presentation
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22-09-2010, 11:17 AM
More Info About Cryogenic Engines
More Info About Cryogenic Engines
Joined: Nov 2012
30-11-2012, 05:55 PM
CRYOGENIC ENGINE.ppt (Size: 1.2 MB / Downloads: 85)
Cryogenics originated from two Greek words “kyros” which means cold or freezing and “genes” which means born or produced.
Cryogenics is the study of very low temperatures or the production of the same. Liquefied gases like liquid nitrogen and liquid oxygen are used in many cryogenic applications.
A cryogenic rocket engine is a rocket engine that uses a cryogenic fuel or oxidizer, that is, its fuel or oxidizer (or both) are gases liquefied and stored at very low temperatures.
Notably, these engines were one of the main factors of the ultimate success in reaching the Moon by the Saturn V rocket.
During World War II, when powerful rocket engines were first considered by the German, American and Soviet engineers independently, all discovered that rocket engines need high mass flow rate of both oxidizer and fuel to generate a sufficient thrust.
At that time oxygen and low molecular weight hydrocarbons were used as oxidizer and fuel pair. At room temperature and pressure, both are in gaseous state.
Hypothetically, if propellants had been stored as pressurized gases, the size and mass of fuel tanks themselves would severely decrease rocket efficiency.
Therefore, to get the required mass flow rate, the only option was to cool the propellants down to cryogenic temperatures (below −150 °C, −238 °F), converting them to liquid form. Hence, all cryogenic rocket engines are also, by definition, either liquid-propellant rocket engines or hybrid rocket engines.
Various cryogenic fuel-oxidizer combinations
have been tried, but the combination of liquid
hydrogen (LH2) fuel and the liquid oxygen (LOX)
oxidizer is one of the most widely used.
Both components are easily and cheaply available,
and when burned have one of the highest entropy
releases by combustion, producing specific
impulse up to 450 s
\(effective exhaust velocity 4.4 km/s).
The major components of a cryogenic rocket engine are the combustion chamber (thrust chamber), pyrotechnic igniter, fuel injector, fuel cryopumps, oxidizer cryopumps, gas turbine, cryo valves, regulators, the fuel tanks, and rocket engine nozzle.
In terms of feeding propellants to combustion chamber, cryogenic rocket engines (or, generally, all liquid-propellant engines) work in either an expander cycle, a gas-generator cycle, a staged combustion cycle, or the simplest pressure-fed cycle.
The cryopumps are always turbopumps powered by a flow of fuel through gas turbines. Looking at this aspect, engines can be differentiated into a main flow or a bypass flow configuration.
In the main flow design, all the pumped fuel is fed through the gas turbines, and in the end injected to the combustion chamber. In the bypass configuration, the fuel flow is split; the main part goes directly to the combustion chamber to generate thrust, while only a small amount of the fuel goes to the turbine.
For using cryogenic propellants, special insulated containers and vents are used to prevent gas from the evaporating liquids to escape.
The liquid fuel and oxidizer are fed from the storage tank to an expansion chamber. Then it is injected into the combustion chamber.
In this chamber, they are mixed and ignited by a flame or spark.
The fuel expands as it burns and the hot exhaust gases are directed out of the nozzle to provide thrust.
ROCKET ENGINE POWER CYCLES
Gas pressure feed system :
A simple pressurized feed system is shown schematically below. It consists of a high-pressure gas tank, a gas starting valve, a pressure regulator, propellant tanks, propellant valves, and feed lines.
Additional components, such as filling and draining provisions, check valves, filters, flexible elastic bladders for separating the liquid from the pressurizing gas, and pressure sensors or gauges, are also often incorporated.
After all tanks are filled, the high-pressure gas valve is remotely actuated and admits gas
through the pressure regulator at a constant pressure to the propellant tanks.
The check valves prevent mixing of the oxidizer with the fuel when the unit is not in an right
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