Turbocharger gas turbine

[ganuganu]

Hello everyone after a short gap iam back again to propulsion systems. This time i decided to convert my theoretical knowledge into practice so i decided to build a turbocharger gas turbine engine. Iam a beginner in practical building of gas turbines but to my knowledge i have calculated the dimensions required for a imaginary combustion chamber. What i mean here is initially iam trying to verify myself whether iam ready to build gas turbines or not so here iam assuming a pressure ratio, massflow, inlet pressure and temp and i have designed a CC which suits these criteria. I would like to get some feedback from you all please help me.



Mass Flow: 0.2kg/s

Pressure: 202.6kpa

Temp: 330K

The velocity of air is reduced to 35m/s.

Iam assuming the intake diameter of compressor is 5.08cm.



CC Design:

Flame tube dia is: 10.16cm

Casing dia: 12.7cm

In the flame tube the four zones are:

Primary zone(pz): 8cm

secondary zone(sz): 4cm

Dilution zone(Dz): 14cm

Nozzle zone(Nz): 6cm



In total the overall length of the CC is about 32cm approx 12.6inches.

Now to the number of holes:

Mass flow: 0.2kg/s

Fuel required: 0.0129kg/s

Stoichiometric ratio: 15.5

Number of holes in PZ: 6mm holes - 24

Number of holes in SZ: 9.5mm holes - 8

Number of holes in DZ: 12.7mm holes - 9

Number of fuel injectors: 10 each 2mm dia.

[racket]

Hi

If you put your sizes into Jetspecs www.nuclearprojects.com/jetspecs/flametube.php you can check them against a program that will deliver a working engine .

Fuel burn rate will be at a ratio of ~60:1 overall , so around the same mass of fuel per minute as air per second , A/F ratio in the Primary zone will need to be at ~15:1 .

I'd suggest displacing your air delivery tube further away from the primary zone so as not to cause combustion problems .

Also the flametube MUST fit into a slipjoint at the the turbine scroll end of the combustor so that all air goes through the flametube wall holes , NOT via a annular bypass ring as per your drawing.

May I suggest you checkout our "sister site" , the Yahoo DIY Gas Turbines Site for more information........ groups.yahoo.com/neo/groups/DIYGasTurbines/info , there is a massive amount of data on that Site :-)

Cheers
John

[ganuganu]

Thank you for your reply racket. I checked into jetspecs i have done close calculations so iam a bit happy with my manual calculations. I think the A/F ratio is 15 only in primary zone and A/F 60 will be in dilution zone. Iam sorry for the poor drawing the end of the flame tube must join at the nozzle end i did not draw that well please apologize me. Should i place the delivery tube in between the primary and secondary holes so not to blow out the flame in the primary zone. Thank you once again.

[racket]

Hi
I'd suggest the delivery tube be positioned below the tertiary dilution ,I like to feed it into the combustor opposite the "funnel" feeding the gases into the turbine scroll jetandturbineowners.proboards.com/thread/78/garrett-gt6041-powered-kart?page=6 this allows time for the incoming air to spread around the flametube and "equalise" as it travels towards the primary zone holes so the air enters all holes in a similar manner and keeps combustion centralised within the flametube , a side deliver near the primary zone can force the flame to one side of the flametube or completely disrupt combustion altogether .

Yep , A/F 15:1 in primary and 60:1 after the dilution

Cheers
John

[ganuganu]

I think i got your point correctly please view the attached image. Iam having a question regarding the fuel flow pipe sizing. My calculated value for 15.5 stoichiometric ratio for combustion in primary zone is 0.0129kg/s of fuel. I divided this mass flow to flow through 10 pipes of dia 0.2cm iam not sure about this value bit confused at this point is it correct or not?

[racket]

Hi

Yes , that position for the delivery tube .

I'm not sure what you mean by the "10 pipes" for the fuel delivery , could you provide more information about your fuel system.

Cheers
John

[ganuganu]

I planned to use this type of fuel injection this is what i was trying to say. 10 holes(each 0.2cm dia) will be punched in a single fuel pipe. Is it okay?

[racket]

Hi

This method of fuel delivery isn't a good one , the atomisation isn't fine enough , combustion will be compromised .

What are you using for a fuel pump ??

What fuel pressure will you have

Cheers
John

[ganuganu]

Nov 10, 2013 3:26:54 GMT -5 racket said:

Hi

This method of fuel delivery isn't a good one , the atomisation isn't fine enough , combustion will be compromised .

What are you using for a fuel pump ??

What fuel pressure will you have

Cheers
John

Iam not going to use liquid fuel. Iam going to use only LPG gas as fuel. 

[ganuganu]

Is this design ok for gaseous fuel or should i use a ring shaped fuel injector. Thank you.

[racket]

Hi

With propane/LPG all you need is a single metal tube fitted axially through the end of the combustor/flametube , the end of the metal tube of ~8-10mm dia will need to be crimped/sealed off and 6-12 small diameter holes ( 1 - 1.5mm dia ) drilled evenly around the sidewall of the tube to allow the LPG to spray radially into the flametube .

Under no circumstance should there be any axial injection of the fuel as it will displace the combustion into the turbine wheel .

LPG injection is the simplest method of fueling the engine , be sure to only use metal tubing between LPG cylinder and engine using secure , preferably flared fittings , the LPG cylinder valve can be used as a throttle, or an inline needle valve of smaller bore for small engines like yours , a ball valve for quick shut off of fuel is a useful safety addition to the fuel delivery line .

Cheers
John

[ganuganu]

Thank you very much for the help john. Soon i will post the pictures and video once i succeed in this first project one again thank you.

[racket]

Hi

My pleasure ...........all the best with the build :-)

Cheers
John