A numerical comparison on the aerodynamic performances of a two-stage two-spool turbine facility predicted by steady and unsteady simulations

Authors

R. Spataro, R. Göttlich, C. Santner, F. Heitmeir - Graz University of Technology, Austria

Abstract

The paper discusses the time-averaged and the time-resolved flow in a two-stage two-spool test rig located at the Institute for Thermal Turbomachinery and Machine Dynamics (ITTM) of Graz University of Technology. The facility consists of a transonic turbine stage followed by a counter-rotating subsonic low pressure turbine. The rig was designed and operated within the EU-project DREAM, where the target was to built up a machine able to investigate the aerodynamics of interturbine S-shaped channels. An optimized design of this component represents a critical goal for the performances of modern and future jet engines. The turbine design techniques are nowadays still carried out by optimizations based on steadystate simulations: nevertheless since a long time it is well known how the engine performances are strongly dependent by the unsteady effects. The use of interfaces such as mixing plane or frozen rotor cuts off the real interactions between successive blade rows so that pressure losses and aeroacoustic effects are consequently estimated incorrectly. Such considerations are important for the designer who has to face a highly three dimensional unsteady flow like in a transonic turbine stage. Therefore, the aim of the present paper is to provide a quantitative comparison in terms of performance estimation error whenever a numerical simulation is undertaken in order to catch the time-mean or the time-resolved flow. This paper used data part of the EU-project DREAM (ValiDation of Radical Engine Architecture SysteMs, contract No. ACP7-GA-2008-211861).