Session: 32-06 Purge and Cooling Flows

Paper Number: 152853

Wind Tunnel Testing at TRL4 of EBC Coated SiC/SiC Nozzle Guide Vanes for High-Pressure Turbines With Trailing Edge Cooling 

In order to fulfil the high flight requirements with a significantly lower environmental impact, new approaches to the design of engines are required. One key to being able to build an engine as a whole much more efficiently is the use of a non-oxide ceramic matrix composite (CMC) based on SiC-fibers in a SiC matrix (SiC/SiC) in the most heavily loaded part of the engine: The high-pressure turbine. The non-oxide CMC is a suitable material since it can withstand high temperatures and has only one third of the density of conventional nickel-based alloys, while at the same time offering promising thermal conductivity at the operating temperatures. Together, these properties require less cooling air to be used and save weight in the structure of the engine due to the low weight of the vane. The result can be a lighter and extremely efficient engine design. Nevertheless, there is a high challenge in the component development of SiC/SiC CMCs, which DLR has taken on and for the first time produced a first high-pressure turbine stator made of SiC/SiC CMC with a newly developed EBC coating [1]. This raised the development level of DLR SiC/SiC CMCs from TRL3 to TRL4. Previously, applications were limited to flat specimens. A UHBR-GTF engine [2] developed at DLR was used as the design environment for the stator, with which initial estimates of the temperature savings achieved by SiC/SiC were investigated [3]. The CMC stator vane is internally convectively cooled via impingement cooling and additional trailing edge cooling.

Part of the feasibility study is a wind tunnel test at TRL4 in the Wind Tunnel for Straight Cascades in Göttingen (EGG). The results from the wind tunnel tests are presented in this paper. The vane performance at different cooling blowing rates is analysed. The EBC coating has a low roughness and therefore a nearly complete laminar boundary layer on the suction side with the transition observed near the trailing edge at subsonic flow. The transition location on the suction side was detected using an infrared camera and additionally with time-resolved temperature-sensitive paint (iTSP). The latter is a DLR development that allows measurements of temperature fluctuations on the surface in the transonic range at frequencies of up to 2000 Hz [4].

References

 

[1] F. Süß, R. Schöffler, L. Friedrich, A. Petersen, F. Vogel, M. Frieß und A. Ebach-Stahl, „Design and Manufacture of EBC Coated SiC/SiC Nozzle Guide Vanes for High-Pressure Turbines,“ Journal of Engineering for Gas Turbines and Power, pp. 1-47, September 2024.

[2] M. Vieweg, S. Reitenbach, C. Hollmann, M. Schnös, T. Behrendt, A. Krumme, T. Otten und R. M. zu Ummeln, „Collaborative Aircraft Engine Preliminary Design using a Virtual Engine Platform, Part B: Application,“ in AIAA Scitech 2020 Forum.

[3] P. Wehrel, R. Schöffler, C. Grunwitz, F. Carvalho, M. Plohr, J. Häßy und A. Petersen, „Performance and Emissions Benefits of Cooled Ceramic Matrix Composite Vanes for High-Pressure Turbines,“ Journal of Engineering for Gas Turbines and Power, Bd. 145, p. 121016, October 2023.

[4] A. Petersen und M. Hilfer, „Boundary Layer Analysis of a Transonic High-Pressure Turbine Vane Using Ultra-Fast-Response Temperature-Sensitive Paint,“ Journal of Turbomachinery, Bd. 146, p. 091013, July 2024.

Presenting Author: Anna Petersen DLR

Presenting Author Biography: Anna Petersen has been working at DLR as a research associate since 2012. She completed her doctorate at the TU Braunschweig (ISM) on influencing the unsteady boundary layer interaction of high-pressure turbine stators. Since completing her doctorate, she has been leading a DLR project on the further development of non-oxide ceramics (SiC/SiC) and additive manufacturing for a first turbine stator downstream of the combustor.

Authors:

Anna Petersen DLR
Benjamin Dimond DLR
Anna-Samira Söhngen DLR
Fabia Süß DLR
Andrea Ebach-Stahl DLR
Ravisankar Naraparaju DLR
Michael Hilfer TU Braunschweig
Robin G. Brakmann DLR