High-speed LPT; Off-design; Open database; Secondary flows; Transonic linear cascade; High Speed; High-speed low-pressure turbine; Linear cascade; Low Mach numbers; Low-pressure turbines; Off designs; Reynold number; Test case; Engineering (all)
Abstract :
[en] In this two-part paper, a novel test-case for transonic low-pressure turbines (LPT) is presented. The current study is a comprehensive report on the design, commissioning and testing of a high-speed LPT cascade. Part II reports the characterization of the aerodynamics at on- and off-design flow conditions. A detailed analysis of the steady aerodynamics of the high-speed low-pressure turbine blade is presented for a range of engine representative outlet Mach numbers from 0.70 to 0.95 and Reynolds numbers from 65,000 to 120,000. The blade 3D aerodynamics are characterized using an innovative set of traversable blades, enabling high-resolution radial measurements. A novel method to estimate the location of separation-reattachment based on pneumatic tap measurements is presented. The separation on the blade suction side is strongly influenced by the Reynolds number at the lower Mach numbers, while open separations were observed at transonic exit conditions independently on the Reynolds number. Downstream measurements by means of a five-hole probe, and pressure taps located in the passage endwall are employed to study the secondary flow development and structures at the cascade outlet. The results show that the losses follow different trends at high and low Reynolds numbers. The profile losses at Re = 70k decrease with increasing Mach number, contrary to what is observed for Re = 120k. The minimum secondary flow losses are found for an off-design condition with lower Mach number with respect to the nominal. The off-design comparisons presented in this paper indicate that at low Reynolds, operating at transonic outlet Mach numbers leads to beneficial effects on the performance.
Simonassi, L.; Turbomachinery and Propulsion Department, Von Karman Institute for Fluid Dynamics, Sint-Genesius-Rode, Belgium
Torre, Antonino Federico Maria ; Université de Liège - ULiège > Aérospatiale et Mécanique (A&M) ; Turbomachinery and Propulsion Department, Von Karman Institute for Fluid Dynamics, Sint-Genesius-Rode, Belgium
Patinios, M.; Turbomachinery and Propulsion Department, Von Karman Institute for Fluid Dynamics, Sint-Genesius-Rode, Belgium
Lavagnoli, S.; Turbomachinery and Propulsion Department, Von Karman Institute for Fluid Dynamics, Sint-Genesius-Rode, Belgium
Language :
English
Title :
AN EXPERIMENTAL TEST CASE FOR TRANSONIC LOW-PRESSURE TURBINES - PART 2: CASCADE AERODYNAMICS AT ON- AND OFF-DESIGN REYNOLDS AND MACH NUMBERS
The authors gratefully acknowledge funding of the SPLEEN project by the Clean Sky 2 Joint Undertaking under the European Unions Horizon 2020 research and innovation program under the grant agreement 820883.
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