Following completion of the three-year redesign and planning phase, the TSV2 transonic compressor test rig was converted and is now in operation as the Fan Rig Darmstadt (FRD). With the FRD, the institute is expanding its research infrastructure and now operates a test rig for investigating fans – a central component of modern turbofan engines – in addition to the TSV1 compressor test rig and the LSTR turbine test rig. The GLR now has two state-of-the-art aeromechanical test rigs (TSV1 and FRD) at its disposal, giving it outstanding research infrastructure and expertise in the field of fluid-structure-interaction – a central and safety-critical area of current aviation research.

The new test rig has a 1.8 MW electric motor and a planetary gearbox that enables rotor speeds of up to 18,900 rpm and thus supersonic flow conditions at the rotor tips. The fan stage is highly modular and therefore flexible in design. It consists of a rotor with a diameter of approx. 44 cm and a hub-to-tip-ratio of approx. 0.3, as well as a stator. With the current configuration, mass flows of up to 29 kg/s can be achieved.

In addition to standard aerodynamic instrumentation (rakes, probes, multi-hole probes), the test rig is equipped with sensors for time-resolved recording of aerodynamic and structural interaction. Capacitive sensors (blade tip timing and tip clearance), piezoresistive wall pressure transducers and strain gauges on the rotor blades are used for this purpose. With over 300 stationary and around 100 time-resolved active sensors, this test rig is excellently equipped for its research objectives. The enormous amounts of data (up to 4TB/day) are evaluated using analysis methods that have been continuously developed over many years and provide detailed insights into the physical effects of fluid-structure-interaction.

The operational readiness of the new test rig was officially confirmed after completion of the Test Readiness Review (TRR) on 12th of September 2025 in the presence of representatives from industry partner Rolls-Royce plc. The first measurement campaign was then started with the mechanical and aerodynamic commissioning.

The initial focus of research is on aeroelasticity and aeroacoustics. Various fan rotors are being investigated and compared with each other in order to improve understanding, prediction and thus prevention of fan flutter. Fan flutter is a self-excited instability in fluid-structure-interaction that can lead to high structural loads on the rotor blades. Since these loads can cause engine failure, fan flutter is a key topic in current research in the field of aerospace propulsion.

The FRD team and the institute would like to express their gratitude for the trust placed in us and look forward to the future collaboration and successful measurement campaigns!

Funded by the European Union, under Grant Agreement No 101102004. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or Clean Aviation Joint Undertaking. Neither the European Union nor Clean Aviation JU can be held responsible for them.