Cryogenic Rocket Engine

                            Cryogenic Rocket Engine

Meaning of Cryogenics

                        In physics, cryogenics is the study of the production of very low temperature(below −150 °C, −238 °F or 123 K) and the behavior of materials at those temperatures

Cryogenic technology :

1. Cryogenic technology involves the use of rocket propellants at extremely low temperatures. 
2. The combination of liquid oxygen and liquid hydrogen offers the highest energy efficiency for    rocket engines that need to produce large amounts of thrust. 
3. Oxygen remains a liquid only at temperatures below minus 183 ° Celsius  and hydrogen at          below minus 253 ° Celsius. 

History of Cryogenic Technology:

1. The United States was the first country to develop cryogenic rocket engineswith RL-10 engines, registered its first successful flight in 1963      and is still used on    the                         Atlas V rocket.  
2. Then The Japanese LE-5 engine flew in 1977 ,French HM-7 in 1979 , Chinese YF-73    in 1984. 
3. The Soviet Union, first country to put a satellite and later a human in space, successfully             launched a rocket with a cryogenic engine only in 1987.
   

Ø To India the U.S., Japan and France would either not provide the technology or do so only at an exorbitant price.

Ø The 11D56 cryogenic engine had been developed for one of the upper stages of the mammoth N1 rocket, the Soviet equivalent of Saturn V. But after four successive launch failures, the N1 project was scrapped and its engines were mothballed.

Ø The deal violated the Missile Technology Control Regime, which was intended to prevent the spread of missile-related technology, and fell foul of the U.S. laws meant to enforce its provisions. Despite warnings from within the organization, ISRO opted to go ahead with the import. In May 1992, the U.S. imposed sanctions on ISRO and Glavkosmos. A year later, Russia, which received the contract after the break-up of the Soviet Union, backed out of the deal.

Ø ISRO then had no option but to develop the technology on its own.

Ø At the time, ISRO gave the impression that much of the technology had already been acquired and further development would be quick.

Ø A GSLV with an indigenous cryogenic engine would be ready to fly in about four years, Chairman U.R. Rao told  in July 1993. Instead, it has taken 16 years.

    

 Working:

Ø It involves a complicated ‘staged combustion cycle' to increase the engine efficiency.

Ø Hydrogen is partially burnt with a little oxygen in a gas generator. The hot gases drive a turbo-pump and are then injected at high pressure into the thrust chamber where the rest of oxygen is introduced and full combustion takes place.

Ø Before going to the gas generator, the incredibly chilly liquid hydrogen is used to cool the thrust chamber where temperatures rise to over 3,0000 ° Celsius when the engine is fired.

Production & Manufacturing

Ø The Indian cryogenic engine is produced by Godrej and the Hyderabad-based MTAR Technologies working together as a consortium.

Ø Instead of ISRO first mastering the technology and transferring it to industry, the two companies were involved from the start and even the early prototypes were built by them.

Why didn't the cryogenic engine of India ignite:

—  The GSLV D3, which lifted off well from Sriharikota on Thursday, April 15, 2010 later plunged into the sea as the indigenous cryogenic engine failed to ignite.

—  The vehicle lifted off as planned at 4.27 p.m. and its performance was normal up to the end of its second stage till 293 seconds from the lift-off.

—  An authoritative former ISRO official said: “It is very clear that the cryogenic engine did not ignite when you look at the curve [of the vehicle's trajectory]

—  the vehicle developed problems when the cryogenic upper stage should have ignited 304 seconds after the lift-off, and it fell into the sea

Advantages:

—  High Energy per unit mass:

            Propellants like oxygen and hydrogen in liquid form give very high amounts of energy per unit mass due to which the amount of fuel to be carried aboard the rockets decreases.

—  Clean Fuels

           Hydrogen and oxygen are extremely clean fuels. When they combine, they give out only water. This water is thrown out of the nozzle in form of very hot vapour. Thus the rocket is nothing but a high burning steam engine

—  Economical

          Use of oxygen and hydrogen as fuels is very economical, as liquid oxygen costs less than gasoline.

Drawbacks:

—  Boil off Rate

—  Highly reactive gases

—  Leakage

—  Hydrogen Embrittlement

—  Zero Gravity conditions