HEXENRAD-TTF

The test rigs of the Chair of Thermal Turbomachines and Aeroengines at the Ruhr University Bochum (IBN Gate 6, https://www.ttf.ruhr-uni-bochum.de/ttf/gruben.html.en) was commissioned in 1984 and hosts a portfolio of compressor as well as turbine test beds. Among the latter, the large two-sided, axial-radial turbine rig (https://www.ttf.ruhr-unibochum.de/ttf/forschung/testbed6.html.en) allows experimental investigations of model highpressure turbines in technologically relevant configurations. Currently, only the 4-stage axial machine is actively used, generating about 1 MW shaft power output, whilst the high-speed expander (max. rotation speed 24.500 rpm) will be commissioned during a further project planned late in 2026, beginning of 2027 (see below).

The old hydraulic break has been replaced by a new break system using an electric generator connected to the turbine by means of a high-performance gear box. This will allow immediate usage of the electric energy generated during experimental campaigns, which will be supplied to the asynchronous electrical motor driving the geared compressor, the latter providing the necessary air flow for the turbine by means of a frequency inverter and low-voltage transformer. This arrangement will guarantee stable operability of both sides of the test rig especially in virtue of a fast, real-time control system necessary for high-speed machine whilst allowing substantial energy savings (up to 70-80%) during tests.

The testbed is operated with air in an open circuit, with a maximum mass flowrate up to 12kg/s and overall pressure ratio of 2.7, reaching 7000 rpm on the axial side (now hosting a 4-stage model highpressure steam turbine) and ~25000rpm on the radial side (a 1-stage radial expander is to be commissioned in the framework of current research projects in 2026-2027). The operating conditions allow the investigation of a broad spectrum of aerodynamic aspects and are supported by the numerical expertise at the Chair (which can be also leveraged upon) so that the behaviour of the machines operated with non-conventional fluids can be easily analysed.

Additional calibration facilities (blower, low-speed rotating cascade) are also available.

Extension of the testrigs with specific fluid operation can be considered within new projects/cooperations.

The Chair and its facilities are embedded in the Faculty of Mechanical Engineering at the RUB, offering a unique scientific environment covering Thermodynamics, Material Science, Carbon Sources and Conversion, Additive Manufacturing, Laser Technologies. The Chair itself offers an all-around spectrum of scientific competences, especially unique computational expertise using the own solvers SharC (see publication list below) specialised in the high-fidelity calculation of non-ideal, turbulent, multi-phase/multi-physics flow. The collaboration with the other Chairs and Institutes of the Faculty offers the unique possibility of contextual fluid and material characterisation, including testing new manufacturing and material technologies (e.g. blading, sensorics, diagnostics) in technologically relevant configurations. The Faculty is equipped with an own highly specialised workshop with extensive manufacturing capabilities (e.g. 5-axes CNC milling machines, 3D-wire printing) 

The facility and its scientific periphery offers an ideal testing environment at intermediate TRL for rotating machinery under conditions which are relevant for technological applications (e.g. power class of the testrig and rotation speeds which can be reached). The multistage turbine can be instrumented for intrusive steady and unsteady measurements as well as telemetric assessments. The machine can be equipped in principle (previous assessment of structural and rotordynamic parameters) with different rotors (stages 3-4 currently instrumented) and blade typologies in stators and rotors and is perfectly tailored for experimental investigations to be accompanied by numerical analyses also comprising data assimilation, which the Chair also offers. The data acquisition and post-processing as well as the newly upgraded infrastructure, supported by scientific and technical competences of the Chair personnel, offer ideal conditions for scientific collaborative projects at TRL 2-6. This combination is not available in other laboratories for the specific purposes addressed by the ECCSEL.