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

Abstract

This paper investigates the effects of inlet turbulence conditions and near-wall treatment methods on the heat transfer prediction of gas turbine vanes within the range of engine relevant turbulence conditions. The two near-wall treatment methods, the wall-function and low-Reynolds number method, were combined with the SST and ωRSM turbulence model. Additionally, the RNG k-ε, SSG RSM, and SST+γ-Reθ transition model were adopted for the purpose of comparison. All computations were conducted using a commercial CFD code, CFX, considering a three-dimensional, steady, compressible flow. The conjugate heat transfer method was applied to all simulation cases with internally cooled NASA turbine vanes. The CFD results at mid-span were compared with the measured data under different inlet turbulence conditions. In the SST solutions, on the pressure side, both the wall-function and low-Reynolds number method exhibited a reasonable agreement with the measured data. On the suction side, however, both wall-function and low-Reynolds number method failed to predict the variations of heat transfer coefficient and temperature caused by boundary layer flow transition. In the ωRSM results, the wall-function showed reasonable predictions for both the heat transfer coefficient and temperature variations including flow transition onset on suction side, but, low-Reynolds methods did not properly capture the variation of the heat transfer coefficient. The SST+γ-Reθ transition model showed variation of the heat transfer coefficient on the transition regions, but did not capture the proper transition onset location, and was found to be much more sensitive to the inlet turbulence length scale. Overall, the Reynolds stress model and wall function configuration showed the reasonable predictions in presented cases. showed the reasonable predictions in presented cases.

Numerical Study on Flow Physics of Damaged Vane Trailing Edge

“…Some thermodynamic and fluid properties of the air are given as follows: (i) specific heat capacity at constant pressure = 1006.43 J/kgK, (ii) thermal conductivity = 0.0242 W/mK, and (iii) dynamic viscosity = 1.7894×10 -5 kg/ms. Since the flow over the vane surface is turbulent, the SST k- turbulence model [9] from the FLUENT solver is selected as this turbulence model can predict reasonable results for the flow field [10][11][12]. The maximum Y+ is lower than 4.5, which is acceptable for using the SST k- model.…”

Numerical Investigation of a Radially Cooled Turbine Guide Vane Using Air and Steam as a Cooling Medium

“…It has been proved that the location, cross-section and mass flow rate of the cooling arrangements are highly influential on the temperature distribution in the vane [18]. Other studies have included thermal barrier coating, the effects of turbulence intensity and material selection [19,20]. Recent developments have suggested replacing compressed air with steam because of its superior heat transfer capabilities.…”