Session: 33-03 Low Pressure Turbines 1

Paper Number: 102828

102828 - Aerodynamics of a High-Speed Low-Pressure Turbine Cascade With Cavity Purge and Unsteady Wakes 

The geared turbofan (GTF) is regarded as a key architecture to fulfil the target reduction in CO2, NOx and noise footprint imposed by flight initiatives due mid 2030s. The gearbox that is introduced in this concept enables the low-pressure turbine (LPT) to operate at higher rotational velocities. Consequently, the flow conditions in the LPT are characterized by low Reynolds number, encountered during cruising, and transonic Mach numbers, resultant from the increased low- pressure spool rotational velocity.

Current efforts in exploring the design space of high-speed LPTs are being done in the scope of the EU SPLEEN project, aiming at accelerating the development of tools to design high-performance and efficient modules through an intensive experimental open access database. Recent works dealt with the characterization of the steady aerodynamics of a high-speed LPT geometry at its on- and off-design point. In addition, the dissemination of the impact of high-speed unsteady wakes on a transonic LPT has been performed at a 2D midpsan level and secondary flow region. The following step towards high-fidelity testing of high-speed LPT geometries in a linear cascade environment is the inclusion of purge flows that would arise from the stator-rotor hub platform in a real machine.

This work characterizes the performance of a high-speed linear cascade operating at engine-relevant Mach and Reynolds number (=0.90=70k), as well as wake reduced frequency (0.95) encountered in GTF under the effect of purge flow injection from an upstream cavity. A cavity geometry representative of the real machine is utilized. The impact of the purge flow is assessed for different purge massflow rates ranging from 0% to 0.90% of the main flow massflow rate. The cascade performance and extent of the purge flow impact is assessed by phase-averaged measurements performed with high-speed and pneumatic instrumentation on the blade surfaces and probes immersed downstream of the cascade.

The results will display the impact of purge on secondary flows in a high-speed linear cascade under the influence of unsteady wakes, the modulation of the wake-boundary layer interaction and characterize the impact of unsteady forcing caused by the combined effect of unsteady wakes and purge flow.

Presenting Author: Gustavo Lopes von Karman Institute for Fluid Dynamics

Presenting Author Biography: Gustavo Lopes currently works as a PhD candidate at the department of Turbomachinery and Propulsion at the Von Karman Institute for Fluid Dynamics. His research focus on the experimental characterization of the combined effect of unsteady wakes and purge flows with secondary flows in high-speed low-pressure turbines.

In 2017, he obtained his BSc Mechanical Engineering at New University of Lisbon with an upper-second class honours.

In 2018, he obtained his MSc Aerospace Engineering at the University of Manchester with distinction.

Authors:

Gustavo Lopes von Karman Institute for Fluid Dynamics
Loris Simonassi von Karman Institute for Fluid Dynamics
Sergio Lavagnoli von Karman Institude for Fluid Dynamics