Unsteady Strong Shock Interactions in a Transonic Turbine : Experimental and Numerical Analysis

The aerothermal performance of highly loaded high-pressure turbines is abated by the unsteady impact of the vane shocks on the rotor. This paper presents a detailed physical analysis of the stator-rotor interaction in a state-of-the-art transonic turbine stage at three pressure ratios. The experimental characterization of the steady and unsteady flowfield was performed in a compression tube test rig. The calculations were performed using ONERA's code elsA. This original comparison leads to an improved understanding of the complex unsteady flow physics of a high-pressure turbine stage. The vane shock impingement on the rotor originates a separation bubble on the rotor crown that is responsible for the generation of high losses. A model based on rothalpy conservation has been used to assess the pressure loss. The analysis of the unsteady forcing relates the shock patterns with the force fluctuations.

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