Experimental flow analysis in a modern turbine rear structure with 3D polygonal shroud under realistic flow conditions

The development of the geared and ultra-high bypass ratio engines has increased demands operational envelope for low-pressure system in commercial aircraft engines. This, turn, requires improvement existing design turbine rear structure (TRS) with further experimental investigation flow. This paper presents a first comprehensive study effect 3D polygonal shroud modern TRS including several vane types: regular vanes, vanes equipped bump served better structural behaviour TRS, thickness to give more internal space passage bearing oil pipes scavenge tubes. Improvement properties modification axisymmetric flow due these engine-relevant compromises lead new challenges terms aerodynamic efficiency. Therefore, detailed aero studies all are required. Experimental investigations were performed at Chalmers University Technology test facility where (LPT) is located upstream provide engine-realistic field TRS. three types arranged into an configuration around each type was studied point off-design conditions constant Reynolds number 350,000. measurements by multihole pressure probes, wall static taps on oil-film visualization technique. results show that thickened handling on-design good turning performance. A presence significantly influences wake formation expressed additional vorticity region created from itself which leads extra losses. condition higher swirl angle revealed small separation reattachment near hub suction side corner vanes. Moreover, analysis visualization, it shown separates under on- conditions. overall represents important validation case future CFD calculations. Further details about loss mechanisms realistic geometries geometry will be discussed full version paper.