Session: 32-05 High-Speed LPT

Paper Number: 153656

Impact of Tailboard Configuration on Flow Periodicity in Transonic Low-Pressure Turbine Cascades 

Future generations of fighter aircraft engines will require Low-Pressure Turbine (LPT) profiles capable of efficient operation under transonic flow conditions. This study, part of the NEUMANN project ("Novel Energy and Propulsion Systems for Air Dominance"), investigates the aerodynamic behavior of state-of-the-art transonic LPT profiles through experimental and numerical validation. A turbine vane passage, developed using literature guidelines and RANS analyses, was tested in the C-3 blow-down high-speed wind tunnel at the von Karman Institute. The test section included several inlet flow control strategies and adjustable tailboards to ensure flow periodicity. The cascade was tested under conditions ranging from highly subsonic to supersonic, with Mach numbers between 0.8 and 1.2 and Reynolds numbers between 700,000 and 1.2 million. High turbulence intensity levels were achieved at the turbine cascade leading edge. Flow periodicity, crucial for accurate flow analysis within the cascade passages, was obtained by adjusting tailboard inclinations and monitoring static pressure trends downstream. Exit Mach numbers, flow angles, and total pressures were measured using a specially designed wedge probe, allowing the computation of total losses for all operating conditions. Flow visualizations were performed using a Z-type Schlieren setup. Reynolds-Averaged Navier-Stokes (RANS) simulations, both steady and unsteady, were conducted for two configurations: an infinite cascade with periodic boundary conditions and the real full-rig setup. These simulations aimed to understand the underlying physics and were quantitatively compared with experimental data, including pressure tap readings and wedge probe measurements, and qualitatively with Schlieren visualizations. This comprehensive comparison allowed for an in-depth evaluation of the setup’s capability to accurately capture transonic flow phenomena in future-generation LPT airfoils, enhancing the understanding of finite-blade configurations in high-speed wind tunnel rigs.

Presenting Author: Alexandre Halby von Karman Institute for Fluid Dynamics

Presenting Author Biography: Alexandre Halby received his Master of Science in Mechanical Engineering from Politecnico di Milano (Italy) in 2023. He is currently a PhD candidate in the Turbomachinery and Propulsion department at the von Karman Institute for Fluid Dynamics and the Department of Aerospace and Mechanical Engineering at the Université de Liège. His primary research focuses on experimental studies of transonic turbine cascades, with a particular focus on implementing aerodynamic and optical measurement techniques in these challenging test cases.

Authors:

Alexandre Halby von Karman Institute for Fluid Dynamics
Giovanni Di Lucia von Karman Institute for Fluid Dynamics
Sergio Lavagnoli von Karman Institute for Fluid Dynamics
Stefano Guidolotti Morfo Design
Matteo Giovannini Morfo Design
Filippo Rubechini Morfo Design
Monica Gily Avio Aero
Andrea Notaristefano Avio Aero