Session: 12-01 LES applied to film cooling

Submission Number: 175991

Gas Turbine Film Cooling at Transonic States: Insights From Highly-Resolved Large-Eddy Simulations 

Wall-resolved LES (WRLES) are performed for a canonical single-hole, transonic film-cooling configuration with systematic variations of coolant temperature and blowing ratio. On the basis of this suite, a WRLES database, obtained with the GPU-accelerated URANOS solver (https://github.com/uranos-gpu/uranos-gpu), is released to push forward understanding and modeling of jet-in-crossflow physics that govern adiabatic effectiveness, heat transfer, and coolant usage in gas turbines.

The database spans a compact matrix of blowing and temperature ratios at fixed cylindrical-hole geometry and transonic mainstream conditions. For each case, 3-D time-resolved fields, wall distributions of adiabatic effectiveness, laterally averaged lines, and jet-trajectory diagnostics are provided. Near-wall resolution is sufficient to support trustworthy wall statistics.

Consistent trends are observed across cases. With increasing blowing ratio, jet lift-off is intensified, the counter-rotating vortex pair is strengthened, and the near-wall coolant fraction is reduced; adiabatic effectiveness becomes less uniform in the lateral direction. At moderate blowing, surface attachment is maintained farther downstream and laterally averaged effectiveness per unit coolant is maximized. Variations in coolant temperature shift these regimes in a systematic manner: colder, denser jets resist lift-off, spread laterally, and preserve wall coverage over longer distances, whereas hotter, lighter jets penetrate more strongly and mix faster. These trade-offs are quantified through interpretable measures—such as jet-core height, wall-normal momentum balance, and recovery distance—so operating points can be selected under coolant-supply constraints.

Transonic compressibility is found to modulate, but not overturn, canonical subsonic behavior. Recovery-related effects, shear-layer shocklets, and weak lip expansions sharpen initial roll-up and slightly advance lift-off at high blowing ratio, while the qualitative ordering of effectiveness with blowing and density ratio remains unchanged. In this way, the database serves as a practical bridge from low-speed insights to engine-relevant conditions.

Beyond regime maps and coverage metrics, modeling essentials that are often absent from the literature are included: Reynolds-stress analysis in the jet shear layer and near-wall region, and turbulent kinetic energy budget. These targets enable focused improvements to eddy-viscosity, Reynolds-stress, and heat-flux closures and support data-assisted corrections that must remain stable across blowing and temperature ratios. Thus, the dataset is organized for immediate use. For design studies, laterally averaged effectiveness, coolant-usage tallies, and normalized heat-flux metrics are supplied at standard streamwise stations to enable clean parametric comparisons without additional processing. For model development, uniform file formats and consistent averaging windows facilitate like-for-like calibration and validation of RANS and wall-modeled LES under cooled, compressible conditions. For research on enhancement strategies (e.g., ramps, trenches, shaped exits), these WRLES cases provide a cylindrical-hole, transonic baseline against which anti-vortex concepts and contouring can be quantified before moving to more complex hardware.

In summary, a coherent, open benchmark for transonic film cooling is provided that consolidates long-standing insights—attachment versus lift-off with blowing ratio, density-ratio benefits for near-wall coverage, and the central role of the counter-rotating vortex pair—under the single, high-resolution umbrella of modern GPU-accelerated LES. By standardizing geometry, reference states, and outputs, the database enables calibration of turbulence and heat-flux models with credible targets, stress-testing of reduced-order and machine-learning predictors, and unambiguous quantification of passive or active control benefits. Shorter iteration cycles between concept, modeling, and experiment are anticipated, along with increased confidence in film-cooling predictions for next-generation high-efficiency turbines. The full dataset and companion analysis scripts are planned for open release on a dedicated GitHub repository.

Presenting Author: Francesco De Vanna Università degli studi di Padova

Presenting Author Biography: Francesco De Vanna is an Assistant Professor in Aeroengines and Fluid Dynamics at the University of Padova, Italy. He earned his Ph.D. in Computational Fluid Dynamics in 2020, focusing on high-fidelity simulations of compressible flows. His research combines advanced turbulence modeling, wall-modeled LES, and high-performance computing to study aerothermodynamics in gas turbines and propulsion systems. He is the lead developer of URANOS, a GPU-accelerated open-source Navier–Stokes solver suitable for the design and the analysis of aeroengines components.

Authors:

Francesco De Vanna Università degli studi di Padova