Types of Rocket Engine @StarSpace

Hello all ,Today we are going to discuss about different ways rocket generates thrust in order to reach the orbit and deploy the payload  (satellite ,an obiter a probe ) . 

Introduction 

 In simple words rocket is a body in which propellant is stored at higher pressure which thrown at a high speed in order to generate thrust .This thrust is generated by the help of a propellant (fluid or fuel that helps in propelling an object in a direction )higher the pressure the propellant is stored the more fast it can fire up the content to generate greater thrust.  In the illustration shown a pump is added to maintain chamber pressures so as to generate higher thrust these also help replace high pressure tanks for deep space propulsion.

Types of Rocket Engines

There are many types of rocket engines (press link to reach to a particular topic ) 

(Note : most of the phrases with this    color font is a link) : 

1. Solid Rocket Booster

2. liquid propellant rocket engines

3. hybrid engines 

4. cold gas thrusters

5. ion thruster/ ion engines

1. Solid Rocket Booster

Solid Rocket Boosters (SRB)or solid rocket motors consists of solid fuel (which is a mixture of fuel and oxidizer set as a solid inside the combustion chamber)   This solid is called the propellant grain.

In the illustration the orange part is the pre mix of oxidizer and fuel , the blank or black region is the hollow region that provides surface area for reactions to happen. Ignition of fuel results in hot gasses getting produced , chamber pressures increases and hot gases escapes out from the nozzle at high velocity to  generating thrust.  

The only draw back of this system is that the fuel (which is already mixed with Oxidizer ) once ignited cannot be controlled that is it cannot be put off and then re ignited since the oxidizer is pre mixed and the reaction and hence cannot be  suddenly stopped. The nozzle helps  control the thrust vector  (that is the rocket booster to control the direction of thrust ).

Solid rocket booster were seen on Space Transportation System ( aka The Space Shuttle ) and is going to be used on the SLS (Space Launch System ) these boosters are also seen on Indian rockets such as  GSLV, HLV and PSLV   

HS200 SRB of HLV (Human rated Launch Vehicle) and S200 SRB of GSLV mk III   

credits : ISRO 

2. Liquid Propellant Rocket Engines

Liquid propulsion include the use of liquid Fuel and Oxidizer stored at a high pressure.

liquids are desirable due to their high density and high   specific impulse ,as a result it requires  relatively smaller volume tanks

There are two types of propellants Monopropellant (includes use of a single propellant with a catalyst that reacts to produce thrust) and Bipropellant ( This system includes use two propellants oxidizer and the fuel )

Bipropellant rocket engine:

This system includes fuel and oxidizer tank and some extreme complicated pluming.

This pluming include turbines which run pump sets to maintain a good flow of fuel and oxidizer and maintains chamber pressures. 

At last the fuel and oxidizer are combusted (ignited) in the combustion chamber and the hot gases are fired out of the nozzle 

How does the turbine and pump (turbo pump) work in maintaining chamber pressures  ?

-->There are two ways in which the pump run 

-->One is that pumps run with the help of electric motors (example Rutherford engine )

but this requires a lot of batteries and electrical connections in the engine . These engines are called Electric pump fed engine 

--> Other way is to burn a little propellant and  the exhaust is  used to run the turbine this turbine in turn rotates the pump with high speed. 

liquid propulsion engines are of different types based upon the different types of pluming done in the system :

--> open cycle : In this kind of cycle the fuel that is burnt in the preburner to run the pump is directly thrown away(combustion in the preburner is usually fuel rich that is more fuel is taken and un burnt fuel comes out along with the exhaust),  this thrown away hot exhaust from the preburner is fuel rich  hence the exhaust that comes out is blackish 

 

--> closed cycle : In this kind of engine cycle the exhaust from the pre burner is put into combustion chamber . Hence the fuel is utilized properly  and there is better efficiency 

closed cycle engine are of three types :oxidizer rich cycle , fuel rich cycle with dual shaft , and Full Flow staged combustion cycle .   

Here is a illustration showing different types of cycles present in a liquid propulsion system 

credits : Everyday Astronaut 

-->Pressure Fed Engine  : Is a normal liquid engine tank attached with extra pressurized gas to increase chamber pressure .    

Cryogenic Rocket Engines : Are those engines that uses cryogenic fuels . These are those fuels that are stored at  low temperatures of about  20 kelvin (-253.15 Celsius) .Example of fuels : oxygen as oxidizer and hydrogen as the fuel . storing of these propellants in form of liquid require a very low temperature since boiling points of these gases are too very low .

example of some cryogenic rocket engine : RL-10 (a LH2/LO2 engine ), CE-7.5 (an Indian  LH2/LO2 rocket engine )

Hypergolic Rocket Engines : Are those type of liquid propellant Rocket Engine that use hypergolic propellant .These propellants include oxidizer and fuel that when come into contact ignite itself (they spontaneously combust ). These do not require low temperatures to be stored and can be easily sored over a long time . but there is only an issue these are toxic and hence are hard to handle .Example of fuels: Hydrazine(N₂H₄) as fuel and dinitrogen tetroxide(N₂O₄) as oxidizer. 

3. Hybrid Engines

It is the hybrid of oxidizer tank from the liquid propulsion system and solid rocket booster. Here in the illustration orange part is orange part is the fuel and the blue part is the oxidizer. Here the  oxidizer which is stored at some pressure  helps maintaining a good chamber pressure and also lets throttle the rocket and even lets cut off the engine for a while and restart it again .

watch this video on how this person made a 3d printed Hybrid Rocket Engine -->https://youtu.be/bsmBur9iVxg 

4. Cold Gas Thrusters

Cold Gas thrusters are the kind of thruster that uses cold and pressurized gases like Nitrogen to produce thrust . These are mostly used in rockets as part of Reaction Control System so as to bring course corrections or to change the orientation of  the rocket . Rockets like SpaceX falcon 9 boosters does it to orient back towards the earth  and land them.

Space X Falcon 9 booster orienting it self back to wards earth 

credits : SpaceX

5. Ion thruster Ion Engines 

 Ion Thrusters are the thrusters used on space crafts in space to propel them to their desired spot. in this system Ions of the fuel are accelerated using electricity in order to produce thrust .

spacecraft during a hot fire test of ion thruster  

credits : NASA  

This type of thruster has a good application in deep space propulsion. It is a very 

 efficient since they use a very little fuel in order to produce thrust . Ion thruster has the capability of speeding up the space craft up to 90,000 meter per second . since they use very little fuel the thruster can run for a very long time . Ion thrusters fuel such as Xenon , Iodine , Argon , Krypton , water and so on , of these Xenon is the most used fuel. 

This is how the whole system works : 

-->At first atoms of the fuel is injected into the ionizer where the electric charge tears electrons out of the structure of the atom resulting in formation of ions (positively charged atom ). 

-->Then a dual screen electrostatically attract these available ions  and then violently repel  them out of the spacecraft .

These Ions which get fired out of the spacecraft with great force generate thrust. 

-->An instrument outside the ion thruster known as Neutralizer then showers free electrons on the beam of ions that are fired out of the spacecraft, ions and electrons combine to form atoms (with no charge ). 

  hence he system produces thrust and keeps the spacecraft from getting electrically charged.

Here are some examples of space crafts with ion thrusters : 

-->SERT-1 spacecraft  was the first space craft to use ion thruster 

-->One of the Indian company Bellatrix is the first to use water as the propellant in ion thrusters (satellite propulsion )watch video to know more 

-->https://www.youtube.com/watch?v=PO-qO-fCX90   

Thank you all for reading this blog  

Writer: SWAPNIIL(@starspace)

Image courtesy to : Everyday Astronaut , NASA, ISRO , Wikipedia , SpaceX, Starspace 

visit  starspace home page : https://swap-starspace.blogspot.com/

Note : most of the phrases with this    color font is a link