Graz University of Technology – Institute for Thermal Turbomachinery and Machine Dynamics

The research focus of the Institute for Thermal Turbomachinery and Machine Dynamics at the Technical University is the investigation of thermal turbomachinery, currently mainly in the field of aircraft engines. This includes classical stationary and transient aerodynamics as well as the aeroelastic behaviour of blades or the transport of sound through turbine stages. The aim is to improve the methods for predicting and designing turbomachinery.

The Institute for Thermal Turbomachinery and Machine Dynamics has been a valuable research partner for the aviation industry on the drive side for many years. Many cooperations with companies such as General Electric, MTU Aero Engines, Avio Aero, GKN Aerospace (formerly Volvo Aero), Turbomeca, Snecma, ITP, Rolls Royce, etc. within EU projects enabled the experimental study of so-called turbine intermediate structures. These are components of civil aircraft engines located between the fast-running high-pressure turbine (HDT) and the slow-running low-pressure turbine (NDT). The flow must be safely steered from the turbine outlet of the HDT to the turbine inlet of the NDT over a larger radius and thereby decelerated. During development, a compromise must be found between overall length and thus weight as well as the quality of the flow guidance. In new configurations, the deflection task of the following guide vanes is integrated into the support ribs of the intermediate channel in order to achieve a considerable weight reduction of the entire engine by saving these guide vanes.

This is also the case in the current Clean Sky 2 Joint Undertaking Project TRAVIATA (Turbine Research for Aerodynamical Vane-frame Improvements in Advanced Two-spool Arrangements) funded by the European Union within Horizon 2020 (grant agreement No 785313):
For the aerodynamics of TVF modules (TVF – Turning Vane Frame) of future UHPE architectures (UHPE – Ultra-High Bypass Ratio Engine), interaction with the HDT and NDT rotors plays an important role in the loss generation and must therefore already be taken into account at the design stage. The TVF inlet flow is characterised by the structures of the HDT, such as afterflows, secondary, and gap flows as well as cooling air outlets from the wheel side spaces. In order to obtain meaningful test results for aerodynamic design, it is important to also create engine-relevant inflow and outflow conditions for the TVF under study. The main objective of this project is therefore to conduct a TVF aerodesign test programme together with an upstream HDT and a downstream NDT, representing the flow in a future civil geared turbofan engine. Since the performance of an HDT-NDT transition channel depends on the degree of inhomogeneity in the inflow, a variation of the rotor gap and the cooling air discharge should be carried out during the tests.
The investigations will take place in the twin-shaft transonic test turbine plant at Graz University of Technology, which is also equipped with a suitable secondary air system. In addition to conventional measurement techniques such as pressure and temperature rakes and pneumatic probes, more advanced methods such as fast pressure probes and tracer gas measurement techniques are also used to study component interaction. This guarantees that the necessary input can be provided for a subsequent ‘Ground Test Demo’.

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