Is jet turbine intake mass-flow rate linear proportional with its fan speed (N1)?

  • $\begingroup$ Or is maybe more linear related to fuel consumption rate, or thrust? $\endgroup$
    – Invariant
    Commented Apr 16, 2017 at 0:11
  • $\begingroup$ Is this a homework question? It kind of sounds like one. $\endgroup$ Commented Apr 16, 2017 at 1:03
  • $\begingroup$ Mass flow and thrust are closely related, and we have answered how thrust depends on engine speed here. The short answer is No. $\endgroup$ Commented Apr 16, 2017 at 7:40
  • $\begingroup$ No its not homework. Thank you, @PeterKämpf $\endgroup$
    – Invariant
    Commented Apr 16, 2017 at 13:25
  • 1
    $\begingroup$ Done now @daniel $\endgroup$
    – Invariant
    Commented Apr 17, 2017 at 14:40

1 Answer 1


Not linear, because the back side of N1 will influence the flow. Not only that but the flow is non linear with respect to rotation in most axial flow compressors.

Is there a specific engine or cycle that you are wondering about, because that changes the answer to your question?

  • $\begingroup$ Yes, the engine is Volvo RM8. I am simulating it, and have some info on it when its running, I need to find something that is linear or close to that with regards to the intake mass flow. I have thrust, fuel consumption, N1 and N2. $\endgroup$
    – Invariant
    Commented Apr 17, 2017 at 15:28
  • $\begingroup$ Then I would stick by the non linear model, as it is a two spool turbine. If you can't get good data form airframe applications, that was used for ship propulsion, and you might get data that way. Remember that N1 is quadratic to thrust. $\endgroup$
    – mongo
    Commented Apr 17, 2017 at 16:23
  • $\begingroup$ You might look up a paper by T Abbott of Langley (1990) on engine monitoring. $\endgroup$
    – mongo
    Commented Apr 17, 2017 at 16:28
  • $\begingroup$ Many thanks @mongo. $\endgroup$
    – Invariant
    Commented Apr 17, 2017 at 16:41

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