Periodic Reporting for period 3 - TRAVIATA (Turbine Research for Aerodynamical Vane-frame Improvements in Advanced Two-spool Arrangements)
Periodo di rendicontazione: 2021-03-01 al 2021-09-30
Equipped with a unique test turbine facility, Graz University of Technology has been at the forefront of European research and development of turbine intermediate duct aerodynamics going back 10-15 years and has also contributed in the testing of different TMTF developments. In the aerodynamics of TVF modules the interaction with the HPT and LPT rotor is one of the major key factors for loss generation and has to be accounted for already in the design process. The TVF inlet flow is driven by the HPT flow effects including wakes, secondary flow effects and tip leakage as well as purge flows. In order to provide relevant test data to guide the TVF aerodynamic design, it is critical that engine-relevant TVF inlet and exit flow conditions are provided. Therefore the main objective of the project TRAVIATA was to execute rig tests of TVF aerodynamic designs, coupled with an upstream HPT stage and downstream LPT blade, in a flow environment representative of future GTF aero-engine applications. Since the performance of any HPT-LPT transition duct is impacted by the level of the incoming flow effects, a variation of HPT tip gap and purge flow levels was planned.
The two-spool transonic test turbine facility at TU Graz equipped with a secondary air system (SAS) was used for performing these investigations. Besides conventional measurement with rakes and pneumatic probes advanced instrumentation such as fast response pressure probes, hot-wire and optical measurement techniques as well as concentration measurements were used. In this way not only the pure component performance, such as pressure loss, was evaluated but also the unsteady three-dimensional interaction between the neighbouring components. With the help of the SAS the influence of different independent purge flows and their variations onto the TVF aerodynamics were investigated for the first time. The improved understanding of the flow effects made it possible to rise the technology readiness level from TRL4 to TRL5 and to provide the input for a Ground Test Demo (TRL6) within the Clean Sky 2 programme.
TU Graz was also in charge of all the other test preparations including assembly, instrumentation and commissioning. After that a prolonged seven-month testing period of the TVF setup took place. The experimental campaign uses as planned conventional but also additional new advanced measurements techniques such as a Two-Sensor-FRAPP and concentration measurements with seed gas in order to track the path of purge air through the duct and study their interaction with other components. Therefore, it has to be mentioned that for the application of the concentration measurement technique the rig was also adapted in terms of seed gas insertion and the test hardware equipped with arrays of surface taps.
The measured test data has been shared with GE and analysed in detail in regular team meetings. GE leveraged the measured dataset to compare against the design intent of the TVF and LPT test vehicle. Comparisons were made with measured total pressure profiles at the TVF inlet and exit, with the TVF exit contours and also for TVF static pressure profiles, consistently showing good agreement between measured data and CFD results. This rig test successfully validated the design intent, one of the most important objectives of the entire project. The gained measurement results and the application of new measurement techniques and data analysis methods were the basis of several conference and journal publications. The dissemination of the outcomes is not yet finished, further articles are planned for upcoming turbomachinery conferences as well as for scientific journals.
The project enabled TU Graz to continue the research work on intermediate turbine structures. In combination with already executed projects it has improved the expertise of TU Graz and strengthend the position as valuable strategic partner for the aeronautical industry.
Two PhD positions were provided over the whole scheduled timeline. One PhD thesis has already been finished, the second one is well on the way. Therefore not only the topic manager GE and TU Graz benefit from Clean Sky 2. Also the community will gain general new insights through these doctoral theses and the related publications from the project TRAVIATA. This will support TU Graz known as attractive employer for scientific personnel such as post-docs and PhD-students also in the future.
TRAVIATA was part of the Clean Sky 2 Joint Undertaking under the European Union’s Horizon 2020 research and innovation program under grant agreement No 785313.