A POD-Based Procedure for the Split of Unsteady Losses of an LPT Cascade

Lengani, Davide; Simoni, Daniele; Ubaldi, Marina; Zunino, Pietro; Bertini, Francesco

doi:10.3390/ijtpp2040017

Cited by 10 publications

(7 citation statements)

References 34 publications

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“…In LES, the splitting can be obtained by taking advantage of the unsteady nature of the method. The total viscous irreversibilities produced s ∇u can be written as [25][26][27]30,46] :…”

Section: Measure Of Loss Based On Entropymentioning

confidence: 99%

Loss assessment of a counter rotating open rotor using URANS/LES with phase-lagged assumption (draft)

2021

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“…In LES, the splitting can be obtained by taking advantage of the unsteady nature of the method. The total viscous irreversibilities produced s ∇u can be written as [25][26][27]30,46] :…”

Section: Measure Of Loss Based On Entropymentioning

confidence: 99%

Loss assessment of a counter rotating open rotor using URANS/LES with phase-lagged assumption (draft)

2021

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“…In LES, the splitting can be obtained by taking advantage of the unsteady nature of the method. The total viscous irreversibilities produced Φ ∇u can be written as follows [32,[60][61][62][63]:…”

Section: Near-wall Flowmentioning

confidence: 99%

Reynolds, Mach, and Freestream Turbulence Effects on the Flow in a Low-Pressure Turbine

Fiore

Gourdain

2021

Journal of Turbomachinery

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This paper presents the Large Eddy Simulation of a Low-Pressure Turbine Nozzle Guide Vane for different Reynolds (Re) and Mach numbers (Ma) with or without inlet turbulence prescribed. The analysis is based on a slice of a LPT blading representative of a midspan flow. The characteristic Re of the LPT can vary by a factor of four between take-off and cruise conditions. In addition, the LPT operates at different Ma and the incident flow can have significant levels of turbulence due to upstream blade wakes. The paper investigates numerically using LES the flow around a LPT blading with three different Reynolds number Re = 175'000 (cruise), 280'000 (mid-level altitude) and 500'000 (take-off) keeping the same characteristic Mach number Ma = 0.2 and three different Mach number Ma = 0.2, 0.5 and 0.8 keeping the same Reynolds number Re= 280'000. These different simulations are performed with 0% Free Stream Turbulence (FST) followed by inlet turbulence (6% FST). The study focuses on different flow characteristics: pressure distribution around the blade, near-wall flow behavior, loss generation and Turbulent Kinetic Energy budget. The results show an earlier boundary layer separation on the aft of the blade suction side when the Re is increased while the free-stream turbulence delays separation. The TKE budget shows the predominant effect of the turbulent production and diffusion in the wake, the axial evolution of these different terms being relatively insensitive to Re and Ma.

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“…In LES simulation, the splitting can be obtained by taking advantage of the unsteady nature of the method. The total viscous irreversibilities produced ∇u can be written as [19][20][21]23,40] :…”

Section: Rans/les Comparison: Viscous Lossesmentioning

confidence: 99%

Description of the flow in a linear cascade with an upstream cavity part 2: Assessing the loss generated using an exergy formulation (draft)

et al. 2020

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Purge air is injected in cavities at hub of axial turbines to prevent hot mainstream gas ingestion into interstage gaps. This process induces additional losses for the turbine due to an interaction between purge and mainstream flow. To deal with this issue, this paper is devoted to the study of a low speed linear cascade with an upstream cavity at a Reynolds number representative of a low-pressure turbine using RANS and LES with inlet turbulence injection. Different rim seal geometries and purge flow rates are studied. Details about numerical methods and comparison with experiments can be found in a companion paper. The analysis here focuses on the loss generation based on the description of the flow and influence of the turbulence introduced in the companion paper. The measure of loss is based on an exergy analysis (i.e. energy in the purpose to generate work) that extends a more common measure of loss in gas turbines, entropy. The loss analysis is led for a baseline case by splitting the simulation domain in the contributions related to the boundary layers over the wetted surfaces and the remaining domain (i.e. the complementary of boundary layers domains) where secondary flows and related loss are likely to occur. The analysis shows the strong contribution of the blade suction side boundary layer, secondary vortices in the passage and wake at the trailing edge on the loss generation. The study of different pur ge flow rates shows increased secondary vortices energy and subsequent loss for higher purge flow rates. The rim seal geometry with axial overlapping promotes a delayed development of secondary vortices in the passage compared to simple axial gap promoting lower levels of loss.

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A POD-Based Procedure for the Split of Unsteady Losses of an LPT Cascade

Cited by 10 publications

References 34 publications

Loss assessment of a counter rotating open rotor using URANS/LES with phase-lagged assumption (draft)

Loss assessment of a counter rotating open rotor using URANS/LES with phase-lagged assumption (draft)

Reynolds, Mach, and Freestream Turbulence Effects on the Flow in a Low-Pressure Turbine

Description of the flow in a linear cascade with an upstream cavity part 2: Assessing the loss generated using an exergy formulation (draft)

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