Modell bearing losses of a compressor-turbine shaft in Simscape

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David Reimert
David Reimert on 13 Jul 2021
Answered: Yifeng Tang on 23 Jul 2021
In order to model a compressor-turbine test rig I'm trying to model the bearing losses. I'm using the same compressor/turbine-blocks used in the Aircraft Environmental Control System (Matlab command: ssc_aircraft_ecs). I'm aware that it's possible to implement a mechanical efficiency to the compressor- and the turbine-block. But that's not the solution I'm looking for.
I have empirical values for the bearing losses for different operating points. And the values are expressed in [kW] as the power getting lost in the bearings. A perfect solution for me would be a sink or something that I can connect to the shaft "absorbing" the desired power. Or maybe it could be an option to "cut" the shaft, measure the power, remove the losses and use an ideal source to provide the power gained by the turbine to the compressor. I would be really happy about a solution or ideas that could work.

Answers (1)

Yifeng Tang
Yifeng Tang on 23 Jul 2021
I wonder how is the operating points defined. If you have the shaft speed at these points, it's then possible to find the friction/damping torque from the power lost. You can apply that torque using a torque source (need to figure the direction carefully so you are removing energy). The input S to the torque source comes from a PS lookup table that describe the torque as a function of shaft speed (and something else), which can be provided using sensor measurements.

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