guest ::
%0 Thesis %A Landgraf, Christian %T Betriebsverhalten einer Radialverdichterstufe mit aerodynamisch profiliertem Diffusor; 1. Auflage %I RWTH Aachen University %V Dissertation %C Aachen %M RWTH-2023-08263 %@ 978-3-95886-501-3 %P 1 Online-Ressource : Illustrationen, Diagramme %D 2023 %Z Druckausgabe: 2023. - Auch veröffentlicht auf dem Publikationsserver der RWTH Aachen University %Z Dissertation, RWTH Aachen University, 2023 %X This thesis comprises the experimental investigation of a centrifugal compressor stage with a vaned diffuser and a single row deswirler from an aero engine application. As a comparison experimental data of an alternative stage configuration with the same rotor, a pipe diffuser and a tandem deswirler are considered. Centrifugal compressor stages with pipe diffusers usually exhibit a relatively narrow operating range paired with a high efficiency. The main design objectives of the stage configuration with the vaned diffuser are the achievement of a broader operating range with a minimal penalty in efficiency. Whether the design is successful to that end is to be investigated within this thesis. A detailed analysis of the stage configuration with the vaned diffuser reveals a generally similar performance compared to the pipe diffuser configuration. Throttling of the stage leads to a degressively growing pressure rise in the diffuser inlet region up to its throat. This is attributed to an increasing area ratio in that region and a growing Mach number at the rotor exit. The subsequent diffuser channel up to the stage exit on the other hand encounters a regressively decreasing pressure rise due to a decreasing Mach number at the diffuser throat. As expected the operating range of the vaned diffuser configuration is much broader than that of the pipe diffuser configuration. However, the penalty in efficiency is greater than expected. The static pressure rise of the new design is significantly lower than that of the previous design over the whole operating range and it is accompanied by a high loss in total pressure. The cause for this observation was identified to be a large-scale secondary flow motion originating from the rotor: the throat vortex. It emerges within the diffuser inlet region due to the uniform deflection of the axially distorted rotor discharge flow. The development of this vortex with its axis of rotation parallel to the main flow direction is yet intensified through the large blade pitch of the vaned diffuser. The throat vortex leads to the formation of an extensive zone of low total pressure in the rear region of the diffuser close to its vanes’ pressure sides. The resulting wide blockage of the cross sectional area leads to a decreased effective area ratio of the diffuser and a reduced static pressure rise. The subsequent single row deswirler is exposed to a very inhomogeneous flow with a severe negative incidence and can hence not significantly contribute to the pressure rise of the stage. %F PUB:(DE-HGF)11 ; PUB:(DE-HGF)3 %9 Dissertation / PhD ThesisBook %R 10.18154/RWTH-2023-08263 %U https://publications.rwth-aachen.de/record/967844