Transentulink modelling heat

[marco89pr]

Hello everyone, I have a problem. for the machine workshop the prof gave me to make the simulink modeling of a transient of a classic turbogas ( turbine burner compressor ). I wanted to know if there's anyone willing to help me. I was given the 2 blocks of the compressor and turbine already made and in practice what I have to do and model the combustion chamber. Now that I finish installing matlab I give you the details of the modeling but I would already like to know if there is someone who can help me, obviously I don't want one who does my job but only explanations and/or advice :smile:

 

[volaff]

a presentation would be advisable.

 

[marco89pr]

you know and you're right, it's that I'm having trouble installing matlab...however the 2 compressor and turbine blocks are complete, they have their beautiful tables and according to the expansion compression ratio and the number of laps pull out the flow processed by one or another. In addition to avoid the problems of first start we hypothesize that the transient already leaves from 5000 laps and ambient pressure (it sounds strange sincerely). ..I hope to solve the installation problem soon in order to post an image of the scheme and the necessary dattagli

 

[Fulvio Romano]

I will gladly give you a hand (obviously after you will be presented in the appropriate area).
If we talk about pure matlab I give you a deeper hand, simulink I don't have it under my hand, so I can only give you theoretical suggestions.

 

[marco89pr]

Done! I did not want to be rude... only, I hope I did it in the right section

 

[marco89pr]

then we start from the compressor.
I have:
- mountain pressure (atmosphere 101325 [Pa])
-mountain temperature (Atmospheric 293 [K])
-number of tree turns
- valley pressure
-composition in air volume (it is already assigned and also for fumes you use this)
I have:
- compressor door
- valley temperature
- compressor power
-Composition in gas output volume
the turbine is so made:
incoming -composizine gas
- mountain pressure
-mount temperature
- valley pressure (atmosphere 101325 [Pa])
- number of turns
- opening (there is but does not count and fix)
I have:
-ported turbine
-temperature
-power
there is then a 3rd block to calculate the number of turns based on the generated and absorbed power but also this is already done and I assume that it functions.

 

[marco89pr]

My job is to model the combustion chamber.
now I have begun by placing stakes and that is:
-Alpha (air mass)/(fuel mass) = 60
-eta 0.6
the prof told me that at the instant initial compressor cam. combustion and turbine are at atmospheric pressure (until here ok) in the transitional system the compressor begins to compress air and send it in c.c and here begins to accumulate (after combustion ) until the turbine is able to dispose of the fumes produced

 

[marco89pr]

so I began to say (m_x is for reach of ..)
(m_compressor+m_fuel) - m_turbine=port accumulating (although it is bad to say) such integrated flow over time (with initial condition deriving from p*v=m*r*t) gives me the mass of fumes accumulating in the combustion cam.

 

[marco89pr]

now for me is this accumulation that generates me the fine compression pressure (p2) of the compressor during the transit...calculates the generated p2:
p*v=m*r*t from which p=(m*r*t)/v of course there is a delta p reason why this result will be added to the pressure in t0

 

[marco89pr]

for the entry temperature in turbine I used the formula.....ok here I need to know how I can write formulas clearly otherwise we will never understand!

 

[Fulvio Romano]

but pv=nrt is not only valid for balance states?

However in simulink you can insert a function block. go to the blockset (memory vade) function&tables and selection matlab-function. enter the block, double click and open a .m in which you write the function. you must declare the incoming and outgoing variables that will appear as connectors on the block. write your formula.

 

[marco89pr]

but pv=nrt is not only valid for balance states?
.

I honestly don't know. Anyway I meant to write the function here in the forum on simulink I have no problems

 

[Fulvio Romano]

I honestly don't know. Anyway I meant to write the function here in the forum on simulink I have no problems

write with mathtype and paste an image. . .

 

[marco89pr]

But do you think modeling is right?

 

[marco89pr]

and especially in an instant t the turbine sees the pressure p+il deltap while the compressor still sees p or compressor and turbine see p and in the next instant see p+deltap I don't know if I made the idea

 

[marco89pr]

you guys help me!!! It doesn't take long.

 

[marco89pr]

I begin to doubt the validity of the blocks. I have connected compressor and turbine in series with a speed of 15000 rpm pressure and atmospheric temperature to compressor input and all other parameters visible in the image, after 15 seconds the result on the flow rates processed by compressor ( 1° graph ) and turbine (second graph ) are bewildered because in practice the turbine processes much more flow compared to the compressor (we talk about a factor 10 ) not concurrently the heat. someone inspires me

 

[marco89pr]

Can't anyone help me? ? ?

 

[Fulvio Romano]

I said I'd give you a hand with matlab... but in hot mechanics I am not very prepared, just some university reminiscence. . .

 

[marco89pr]

thank you anyway for your availability