The present paper consists in a numerical analysis of a variable geometry radial turbine stage, for three opening configurations. The presence of the endwall clearance in the stator creates additional secondary flows upstream from the rotor, which tend to increase the stator–rotor interactions. Those interactions are filtered in steady-state simulations, for which the accuracy is expected to decrease. A comparison between steady-state mixing plane simulations and a Non Linear Harmonic (NLH) approach is thus proposed, together with an analysis of the influence of the numbers of harmonics chosen for the NLH simulations. The results show that the implementation of clearances in the simulationsudincreases the discrepancies between the two methods, especially for configurations naturally sensitive to stator–rotor interactions (open stator configuration). Regarding the number of harmonics for the numerical setting, a criterion proposed in the literature is discussed at the end of the paper, and provides good guidelines in order to avoid a full harmonics convergence analysis.
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