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I am trying to understand compressor and turbine design principle based on stators and rotors. I know that turbines and compressors both have a rotating and fixed section that constitute a stage.

For compressors;

1-) Do they begin with rotor and end with stator? (I think there should be rotor at first to capture air in precisely and there should be stator at the end of compressor and in the beginning of combustion chamber since combustion chamber needs the highest pressure of fluid, so we can maximize fluid pressure by slowing down with stator)

For turbines;

2-) Do they begin with rotor and end with rotor? (I think there should be rotor in the beginning of turbines and at the end of combustion chamber to capture air in precisely and there should be rotor at the end of turbines as well since we need dynamic energy instead of static pressure, so we can maximize dynamic energy with rotor just before nozzle.)

Are my understanding and information correct?

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  • $\begingroup$ Having a look inside is always a good way to learn. Let us know if something isn't clear. $\endgroup$
    – sophit
    Commented Apr 13, 2023 at 10:26
  • $\begingroup$ @sophit I looked at it before actually, but am not sure about answer to my question. It seems that compressor begins and ends with rotor, turbine begins with stator and ends with rotor. Am I correct? I think I am not. Because I think if they begin with rotor, they need to end with stator, or exact reverse. $\endgroup$
    – Jawel7
    Commented Apr 13, 2023 at 10:50
  • $\begingroup$ Well, if you consider the fan as the very first stage of the axial compressor then it does begin with a rotor. Just before and after the combustion chamber there are indeed stators to guide the airflow in and out. After the turbine(s) there might be some guide vanes. But let's see what the engine experts say. $\endgroup$
    – sophit
    Commented Apr 13, 2023 at 11:51
  • $\begingroup$ @sophit Older low-bypass engines, like the JT8D, had inlet guide vanes before the fan, so those would be stator. I think the answer to this is "it depends". $\endgroup$
    – user71659
    Commented Apr 13, 2023 at 20:24
  • $\begingroup$ @user71659: that's why I wrote only a comment. But it looks like you have the answer 😉 $\endgroup$
    – sophit
    Commented Apr 13, 2023 at 21:15

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A compressor stage is rotor followed by stator. Many, but not all, have inlet guide vanes (IGV)at the inlet.

Turbine stages are vane (stator) followed by blade (I had a board designer not even know the term, to him the rotor is the spinning shaft). There can be exit guide vanes to straighten the flow.

The IGV forces a tangential velocity on the flow, and the axial component cannot change much (the same flow ahead and behind the IGV) so it does what the turbine vane does: increase speed and decrease static pressure. That gives less problem with separation. Exit guide vanes decrease the tangential velocity and therefore velocity so they work like compressor stators.

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