Abstract
The temporal behaviour of a flow separation in the hub-suction side corner of a transonic diffuser is studied thanks to unsteady numerical simulations based on the phase-lagged approach. The validity of the numerical results is confirmed by comparison with experimental unsteady pressure measurements. An analysis of the instantaneous skin-friction pattern and particles trajectories is presented. It highlights the topology of the separation and its temporal behaviour. The major result is that, despite of a highly time-dependent core flow, the separation is found to be a “fixed unsteady separation” characterized by a fixed location of the main saddle of the separation but an extent of the stall region modulated by the pressure waves induced by the impeller-diffuser interaction.
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Abbreviations
- N1 :
-
Number of blades in the impeller
- N2 :
-
Number of blades in the radial vaned diffuser
- Ω [rad/s]:
-
Rotation speed of the impeller
- T1 :
-
Temporal period of the flow in the impeller
- T2 :
-
Temporal period of the flow in the diffuser
- T0[○K]:
-
Total temperature
- p0 [Pa]:
-
Total pressure
- P:
-
Static pressure
- \(\vec v\) :
-
Flow velocity vector
- \(\dot m\left[ {kg/s} \right]\) :
-
Massflow
- Cp :
-
Static pressure recovery coefficient of the diffuser
- K:
-
Total pressure loss coefficient of the diffuser
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Marsan, A., Trébinjac, I., Coste, S. et al. Temporal behaviour of a corner separation in a radial vaned diffuser of a centrifugal compressor operating near surge. J. Therm. Sci. 22, 555–564 (2013). https://doi.org/10.1007/s11630-013-0662-6
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DOI: https://doi.org/10.1007/s11630-013-0662-6