Gas Turbine Heat Transfer: Past and Future Challenges

Schiele, Ralf; Wittig, Sigmar

doi:10.2514/2.5611

Cited by 28 publications

(8 citation statements)

References 32 publications

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“…Determination of heat loads such as wall temperatures and heat fluxes, is a key issue in gas turbine design [1][2][3][4][5]: the interaction of hot gases with colder walls is an important phenomenon and a main design constraint for turbine blades. In recent gas turbines, the constant increase of the thermodynamic efficiency leads to a turbine inlet temperature that is far beyond the materials melting point.…”

Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulation and Conjugate Heat Transfer in a Round Impinging Jet

Shum-Kivan

Duchaine

Gicquel

2014

Volume 5A: Heat Transfer

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This study addresses and evaluates the use of high fidelity Large Eddy Simulation (LES) for the prediction of Conjugate Heat Transfer (CHT) of an impinging jet at a Reynolds number of 23 000, a Mach number of 0.1 and for a nozzle to plate distance of H/D = 2. For such simulations mesh point localization as well as the turbulent model and the numerical scheme are known to be of primary importance. In this context, a compressible unstructured third order in time and space LES solver is assessed through the use of WALE sub-grid scale model in a wall-resolved methodology. All simulations discussed in this document well recover main unsteady flow features (the jet core development, the impinging region, the deviation of the flow and the wall jet region) as well as the mean statistics of velocity. Convergence of the wall mesh resolution is investigated by use of 3 meshes and predictions are assessed in terms of wall friction and heat flux. The meshes are based either on full tetrahedral cells or on a hybrid strategy with prism layers at the wall and tetrahedral elsewhere. The hybrid strategy allows reaching good discretization of the boundary layers with a reasonable number of cells. Unsteady flow features retrieved in the jet core, shear layer, impinging region and wall jet region are analyzed and linked to the unsteady and mean heat flux measured at the wall. To finish, a LES based CHT computation relying on the finer grid is used to access the plate temperature distribution. Nusselt number profiles along the plate for the isothermal and the coupled cases are also provided and compared.

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Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulation and Conjugate Heat Transfer in a Round Impinging Jet

Shum-Kivan

Duchaine

Gicquel

2014

Volume 5A: Heat Transfer

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“…To promote heat exchange, passage walls are commonly lined with repeated geometrical disturbance elements, which yield improved mixing with the free stream and induce high levels of turbulence to the core flow [1]. This approach is effective in raising the heat transfer to considerably higher levels, at the expense of an inevitably enlarged pressure drop penalty [2].…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Implications of Acoustic Resonances in Turbine Internal Cooling Channels

Selcan

Cukurel

Shashank

2016

Journal of Heat Transfer

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In an attempt to investigate the acoustic resonance effect of serpentine passages on internal convection heat transfer, the present work examines a typical high pressure turbine (HPT) blade internal cooling system, based on the geometry of the NASA E3 engine. In order to identify the associated dominant acoustic characteristics, a numerical finite-element method (FEM) simulation (two-step frequency domain analysis) is conducted to solve the Helmholtz equation with and without source terms. Mode shapes of the relevant identified eigenfrequencies (in the 0–20 kHz range) are studied with respect to induced standing sound wave patterns and the local node/antinode distributions. It is observed that despite the complexity of engine geometries, the predominant resonance behavior can be modeled by a same-ended straight duct. Therefore, capturing the physics observed in a generic geometry, the heat transfer ramifications are experimentally investigated in a scaled wind tunnel facility at a representative resonance condition. Focusing on the straight cooling channel's longitudinal eigenmode in the presence of an isolated rib element, the impact of standing sound waves on convective heat transfer and aerodynamic losses are demonstrated by liquid crystal thermometry, local static pressure and sound level measurements. The findings indicate a pronounced heat transfer influence in the rib wake separation region, without a higher pressure drop penalty. This highlights the potential of modulating the aerothermal performance of the system via acoustic resonance mode excitations.

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“…Determination of heat loads such as wall temperatures and heat fluxes is a key issue in gas turbine design [1][2][3][4][5]; the interaction of hot gases with colder walls is an important phenomenon and a main design constraint for turbine blades. In recent gas turbines, the constant increase of the thermodynamic efficiency leads to turbine inlet temperature that is far beyond the material's melting point.…”

Section: Introductionmentioning

confidence: 99%

Large-Eddy Simulation and Conjugate Heat Transfer Around a Low-Mach Turbine Blade

Duchaine

Maheu²,

Moureau

et al. 2013

Journal of Turbomachinery

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International audienceDetermination of heat loads is a key issue in the design of gas turbines. In order to optimize the cooling, an exact knowledge of the heat flux and temperature distributions on the airfoils surface is necessary. Heat transfer is influenced by various factors, like pressure distribution, wakes, surface curvature, secondary flow effects, surface roughness, free stream turbulence, and separation. Each of these phenomenons is a challenge for numerical simulations. Among numerical methods, large eddy simulations (LES) offers new design paths to diminish development costs of turbines through important reductions of the number of experimental tests. In this study, LES is coupled with a thermal solver in order to investigate the flow field and heat transfer around a highly loaded low pressure water-cooled turbine vane at moderate Reynolds number (150,000). The meshing strategy (hybrid grid with layers of prisms at the wall and tetrahedra elsewhere) combined with a high fidelity LES solver gives accurate predictions of the wall heat transfer coefficient for isothermal computations. Mesh convergence underlines the known result that wall-resolved LES requires discretizations for which y+ is of the order of one. The analysis of the flow field gives a comprehensive view of the main flow features responsible for heat transfer, mainly the separation bubble on the suction side that triggers transition to a turbulent boundary layer and the massive separation region on the pressure side. Conjugate heat transfer computation gives access to the temperature distribution in the blade, which is in good agreement with experimental measurements. Finally, given the uncertainty on the coolant water temperature provided by experimentalists, uncertainty quantification allows apprehension of the effect of this parameter on the temperature distribution

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Gas Turbine Heat Transfer: Past and Future Challenges

Cited by 28 publications

References 32 publications

Large-Eddy Simulation and Conjugate Heat Transfer in a Round Impinging Jet

Large-Eddy Simulation and Conjugate Heat Transfer in a Round Impinging Jet

Heat Transfer Implications of Acoustic Resonances in Turbine Internal Cooling Channels

Large-Eddy Simulation and Conjugate Heat Transfer Around a Low-Mach Turbine Blade

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