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I Want To Try To Build A Turbofan Engine In A Small Scale , What Do I Need?

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#1 HappyNgu

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Posted 04 August 2016 - 08:49 AM

I am in university this year and im trying to make a turbofan engine (my own interest) , 

 

What i understand :

-the air flows in the engine , the compressor compressed it , the combustor heat it , and release it through exhaust to create a trust.

 

What i don`t understand :

-how to build the compressor , what i need ?

-how does the compressor compress air ? (SOLVED)

-does an engine need both axial compressor and centrifugal compressor?

-what is the materials of combustor

-how it create trust ? (SOLVED)

-what is the ideal curve angle of the centrifugal compressor / fan / axial compressor .

 

hope there is someone can help me solve these problems with any kind of solution (online video / online forum links) // (books) or anything els that feel convenient for u.

 

Note : sorry for my bad english if any parts of the forum which u cnt understand what i am talking about , ill edit it.


Edited by HappyNgu, 15 August 2016 - 03:56 AM.


#2 exchemist

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Posted 04 August 2016 - 09:10 AM

I am in university this year and im trying to make a turbofan engine (my own interest) , 

 

What i understand :

-the air flows in the engine , the compressor compressed it , the combustor heat it , and release it through exhaust to create a trust.

 

What i don`t understand :

-how to build the compressor , what i need ?

-how does the compressor compress air ?

-does an engine need both axial compressor and centrifugal compressor?

-what is the materials of combustor

-how it create trust ?

-what is the ideal curve angle of the centrifugal compressor / fan / axial compressor .

 

hope there is someone can help me solve these problems with any kind of solution (online video / online forum links) // (books) or anything els that feel convenient for u.

 

Note : sorry for my bad english if any parts of the forum which u cnt understand what i am talking about , ill edit it.

This is going to be a massive challenge for you if have to ask questions like this. Also the materials and machining you will need will have to be very sophisticated -  unless you steal a turbocharger from a car engine and adapt it, or something like that.  

 

You can easily google "jet engine" and discover the basics. But the compressor can be either centrifugal or axial - centrifugal is a lot easier. It relies on making the air spin and thus get thrown outwards, and then capturing it and ducting it back into the combustion section at a resulting higher pressure. A washing machine pump does something similar, actually. 



#3 sanctus

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Posted 04 August 2016 - 09:13 AM

Welcome!

The only question I can easily answer is "where does the trust come from".
It is simply due to quantity of movement conservation (p=m*v where p is quantity of movement (a vector= has a direction), m is mass and v is velocity(also a vector= has a direction)). What it means is that your system (turbofan) needs to have zero net quantity of movement, so if 1Kg of air moves out of the system in direction A at 2 m/s you get p_{air}=(2,0,0) hence to conserve quantity of movement the turbofan will acquire p_{tf}=(-2,0,0). If we assume the turbofan wighs 2Kgs then it would move in direction -A with speed 1 m/s.

A cool illustration/experiment for kids (but I was no kid, atually second year at university, when I tried it and had a lot of fun) is if you fill a plastic bottle 3/4 full of water and close it it with a wine-cork, which has a small hole for a soccer-ball-pump. Then you hold it with the cork downwards and pump until the pressure makes the cork pop out. If you try this, be sure to not have the head above the bottle ;-), since the water being heavier than the plastic bottle the bottle has to make up in speed for the missing mass.

In case a spoiler, but very advanced is here: https://www.youtube....h?v=8EhQVoyF_0c



#4 HappyNgu

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Posted 15 August 2016 - 03:52 AM

This is going to be a massive challenge for you if have to ask questions like this. Also the materials and machining you will need will have to be very sophisticated -  unless you steal a turbocharger from a car engine and adapt it, or something like that.  

 

You can easily google "jet engine" and discover the basics. But the compressor can be either centrifugal or axial - centrifugal is a lot easier. It relies on making the air spin and thus get thrown outwards, and then capturing it and ducting it back into the combustion section at a resulting higher pressure. A washing machine pump does something similar, actually. 

 

tnx but i already did read all of the topics on google for this .



#5 HappyNgu

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Posted 15 August 2016 - 03:55 AM

Welcome!

The only question I can easily answer is "where does the trust come from".
It is simply due to quantity of movement conservation (p=m*v where p is quantity of movement (a vector= has a direction), m is mass and v is velocity(also a vector= has a direction)). What it means is that your system (turbofan) needs to have zero net quantity of movement, so if 1Kg of air moves out of the system in direction A at 2 m/s you get p_{air}=(2,0,0) hence to conserve quantity of movement the turbofan will acquire p_{tf}=(-2,0,0). If we assume the turbofan wighs 2Kgs then it would move in direction -A with speed 1 m/s.

A cool illustration/experiment for kids (but I was no kid, atually second year at university, when I tried it and had a lot of fun) is if you fill a plastic bottle 3/4 full of water and close it it with a wine-cork, which has a small hole for a soccer-ball-pump. Then you hold it with the cork downwards and pump until the pressure makes the cork pop out. If you try this, be sure to not have the head above the bottle ;-), since the water being heavier than the plastic bottle the bottle has to make up in speed for the missing mass.

In case a spoiler, but very advanced is here: https://www.youtube....h?v=8EhQVoyF_0c

tnx , i did this in my high school , in my country there is a competition for it . it is sure fun , this also remind me how to compressed the wind XD



#6 CraigD

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Posted 18 August 2016 - 03:03 PM

I am in university this year and im trying to make a turbofan engine (my own interest) ,
...
hope there is someone can help me solve these problems with any kind of solution (online video / online forum links) // (books) or anything els that feel convenient for u.

If you’re just trying to build the engine, rather than design it, you can work from one of many detailed plans available for free online, such as this one, for the KJ66 micro jet engine, a small (1.14 kg) one popular in model airplanes.

Ready-to-run engines like this can be bought new from retailers of companies like JetCat USA starting at around US$2,000, if you’d rather leave the difficult work of actually fabricating and assembling one to professionals. Unless you already have a lot of good machine tools, this is likely cheaper than building your own, but for someone who enjoys such work, less satisfying.