Three-Dimensional Conjugate Heat Transfer Simulation of an Internally-Cooled Gas Turbine Vane

Abstract

A conjugate numerical methodology was employed to predict the metal temperature of a three-dimensional gas turbine vane at two different engine-realistic operating conditions. The vane was cooled internally by air flowing through ten round, radially-oriented channels. The conjugate heat transfer approach allows the simultaneous solution of the external flow, internal convection, and conduction within the metal vane, eliminating the need for multiple, decoupled solutions, which are time-consuming and inherently less accurate when combined. Boundary conditions were specified only for the inlet and exit of the vane passage and the coolant channels, while the solid and fluid zones were coupled by energy conservation at the interfaces, a condition that was maintained throughout the iterative solution process. Validation of the methodology was accomplished through the comparison of the predicted aerodynamic loading curves and the midspan temperature distribution on the vane external surface with data from a linear cascade experiment in the literature. The superblock, unstructured numerical grid consisted of nearly seven million finite-volumes to allow accurate resolution of flowfield features and temperature gradients within the metal. Two models for turbulence closure were used for comparison: the standard k-ε model and a realizable version of the k-ε model. The predictions with the realizable k-ε model exhibited the best agreement with the experimental data, with maximum differences in normalized temperature of less than ten percent in each case. The present study shows that the conjugate heat transfer simulation is a viable tool in gas turbine design, and it serves as a platform on which to base future work with more complex geometries and cooling schemes.

Effects of Inlet Turbulence Conditions and Near-wall Treatment Methods on Heat Transfer Prediction over Gas Turbine Vanes

“…5 show excessive overpredictions for the temperature and the HTC around two data points 0.1≤x/C≤0.6. These discrepancies are mainly due to the boundary layer transition as observed and discussed by the other researches [5,18].…”

“…The material has a constant density of ρ=7900 kg/m3, and a specific heat of C P =586.15 J/kgK. The thermal conductivity was specified as λ=0.02017T+6.811 W/mK [18].…”

“…The inlet turbulence length scale, LT (also, unknown from [13]), was set to a value of earlier researches [7,18], and to a value based on the equation (2). When the specific turbulence length scale was defined, the inlet turbulence dissipation was calculated by…”

Film Cooling Modelling for Gas Turbine Nozzles and Blades: Validation and Application

“…As regards the inlet region, flow was assumed to be fully developed at the hole inlets at the hub of the vane, as in the experiment of [89], there were long tubes feeding the channels [102]: flow developed in piping leading coolant through the metered line to the test-bed blade, before entering the tubes. On the base of these considerations, flow inside the channels has been treated as a fully developed one, without considering the entry region, assuming its development occurred in the metered line before reaching the vane.…”

Conjugate Heat Transfer Simulation of the Effect of Tip Clearance on the Thermal Stress of Turbine Rotating Blade Using Genetic Algorithm

“…Kuo-San Ho [5] used the conjugate heat transfer method to compute the temperature field distribution of a high pressure turbine vane and validate it by experiment. York [6] and Facchini [7] used the aero-thermalmechanical conjugate method to analysis the NASA-C3X turbine vane temperature distribution by the software FLUENT and Star-CD separately.…”