How to model combustion chamber or heater for gas turbine system using Simulink?

Hello everyone,

I am trying simulate a gas turbine system for my course on modelling and optimization of energy system. I have come out with a design consisting of a compressor, air preheater, combustion chamber and gas turbine. When I try to do the modelling in Simulink, I couldnt find something similar to combustion chamber. Does anyone have any experience in doing this?

Orginal Design:

I have also amended it and come out with second design, where I change to combustion chamber to a heater and the exhaust air is recycled back to air compressor, making it a closed loop system. But I am also unable to find heater from the simulink library, the closest i can get is convective heat transfer. Can someone help on this too and if the closed loop system is feasible to model?

Design 2 :

Answer 1

[Rishi]

Hi Kheng,

I understand from your query that you want to know if Simulink has any blocks for a combustion chamber or a heater. While such dedicated blocks are not available in Simulink, you can model the essential characteristics of a combustion chamber or a heater by combining several blocks. Here are some blocks you can use to implement your model, along with their documentation:

• Flow Rate Source block to represent the entering air. https://www.mathworks.com/help/simscape/ref/flowratesourceg.html
• MATLAB Function block to incorporate various thermodynamics equations. https://www.mathworks.com/help/simulink/slref/matlabfunction.html
• Transfer Fcn block or State-Space block to model the dynamics of gas temperature and pressure. https://www.mathworks.com/help/simulink/slref/transferfcn.html https://www.mathworks.com/help/simulink/slref/statespace.html
• Convective Heat Transfer block to model the heat exchange between the heated air and the walls of the environment, which can be important for closed-loop systems. https://www.mathworks.com/help/simscape/ref/convectiveheattransfer.html

A closed-loop system is feasible to model in Simulink. You can go through the following examples to learn how to implement it.

• Change Model into Closed-Loop System https://www.mathworks.com/help/simscape/ug/change-model-into-closed-loop-system.html
• Model Thermal Effects in a Closed-Loop System https://www.mathworks.com/help/simscape/ug/model-thermal-effects-in-a-closed-loop-system.html

Hope this helps!

Answer 2

[Yifeng Tang]

Hi Kheng,

For this application, I would highly recommend that you use Simscape and Simscape Fluids for your physical modeling. There are two shipping examples on gas turbine:

https://www.mathworks.com/help/simscape/ug/brayton-cycle-gas-turbine-with-custom-components.html

https://www.mathworks.com/help/hydro/ug/sscfluids_brayton_cycle.html

If you have access to Simscape Fluids, I would suggest that you check out the 2nd one. In both examples, the combustor is modeled using a pipe block and a heat flow rate source, to heat up the gas. The heater in your 2nd design can be modeled this way as well. I guess the hard part is to figure out how much heat to add, and well, that's your problem now :p