In modern aero-engine designs, the low-pressure expansion system includes the Low-Pressure Turbine (LPT), the Turbine Rear Structure (TRS) and the core exhaust nozzle. The TRS is a stator stage located downstream of the LPT which has a structural function to support the engine rear bearings and plays a significant role in de-swirling the flow leading to thrust increase. The TRS struts serve as passages for oil and air transport to the core and the TRS shroud incorporate the engine mounts by which the rear of the engine attaches to the engine pylon in an under-the-wing arrangement. A good aerodynamic design of the TRS is crucial for achieving low pressure losses, minimum disturbances to the upstream LPT, and a well-behaved core jet flow, and all this while maintaining a low component weight. Therefore, in line with reducing emissions from aviation, there is a need for significant need to study the flow of the TRS at engine realistic conditions to allow for increased innovation.                                                        

This paper presents one of the first detailed experimental aerodynamic studies of an engine-realistic TRS at engine-realistic flow conditions. Experiments were performed in a unique facility at Chalmers Laboratory of Fluids and Thermal Sciences. The unique design of the facility includes an open test section that permits investigation of the TRS and nozzle assemblies. The facility is equipped with a 1.5 stage shrouded LPT providing realistic inflow to the tested TRS and operates at flow Reynolds numbers realistic for large turbofan engines. The aerodynamic study was performed by monitoring inlet and outlet planes by multi-hole pressure probes, measuring wall static pressure, measuring the boundary layer by a hot-wire for laminar-turbulent transition detection, measuring at the inlet plane by a time-resolved PIV for understanding the unsteady flow behind the LPT, and by oil-flow visualizations for separation detection.

The aerodynamic study includes investigation of the flow around regular vanes, thick tube vanes with a very large thickness-to-chord ratio, and vanes with an engine-mount recess as in a modern state-of-the-art aero-engine. The studies of the thick tube vane and the vane with the engine-mount recess were performed for the first time in this facility. Furthermore, the influence of the rim-seal purge-flow on the flow in the TRS is studied for the first time as well. The investigation is performed at the design point and several off-design points. The study gave new insights on the laminar-turbulent transition on the TRS vanes, on unsteady inlet flow into the TRS, on the influence of the rim-seal purge-flow and on the aerodynamic performance of three different TRS vane designs at several flow coefficients.


Detailed Experimental Study of the Flow in a Turbine Rear Structure at Engine Realistic Flow Conditions

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

Turbo Expo - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.