The Application of Non-Axisymmetric Endwall Contouring in a Single Stage, Rotating Turbine

Volume 4: Heat Transfer, Parts a and B

Kohli

et al. 2010

Three-dimensional contouring of the compressor and turbine endwalls in a gas turbine engine has been shown to be an effective method of reducing aerodynamic losses by mitigating the strength of the complex vortical structures generated at the endwall. Reductions in endwall heat transfer in the turbine have been also previously measured and reported in the literature. In this study, computational fluid dynamics simulations of a turbine blade with and without non-axisymmetric endwall contouring were compared to experimental measurements of the exit flowfield, endwall heat transfer and endwall film-cooling. Secondary kinetic energy at the cascade exit was closely predicted with a simulation using the SST k-ω turbulence model. Endwall heat transfer was overpredicted in the passage for both the SST k-ω and realizable k-ε turbulence models, but heat transfer augmentation for a non-axisymmetric contour relative to a flat endwall showed fair agreement to the experiment. Measured and predicted film-cooling results indicated that the non-axisymmetric contouring limits the spread of film-cooling flow over the endwall depending upon the interaction of the film with the contour geometry.

Section: Computational Methodologysupporting

confidence: 82%

Computational Predictions of Heat Transfer and Film-Cooling for a Turbine Blade With Non-Axisymmetric Endwall Contouring

Lynch

Volume 4: Heat Transfer, Parts a and B

Kohli

et al. 2010

“…The steady-state RANS and energy equations were solved with the segregated pressure-based SIMPLE algorithm and SST k- turbulence model [38] for closure. The SST k- model has shown reasonable agreement with experimental results in turbomachinery applications [12,20,22,39,40]. The computational domain is shown in Fig.…”

Section: Methodssupporting

confidence: 60%

Conjugate heat transfer analysis of the effects of impingement channel height for a turbine blade endwall

Mensch

International Journal of Heat and Mass Transfer

2015

Advancements in cooling for applications such as gas turbines components require improved understanding of the complex heat transfer mechanisms and the interactions between those mechanisms. Critical cooling applications often rely on multiple thermal protection techniques, including internal cooling and external film cooling in gas turbine airfoils, to efficiently cool components and limit the use of coolant. Most research to quantify the effectiveness of such cooling technologies for gas turbine applications has isolated internal and external cooling in separate experiments. The research presented in this paper uses a conjugate heat transfer approach to account for the combined effects of both internal and external cooling. The geometry used for this study is a turbine blade endwall that includes impingement and film cooling as well as the relevant conduction through the endwall. Appropriate geometric and flow parameters were scaled to ensure engine relevant dimensionless temperatures were obtained. Using the conjugate heat transfer approach, the effect of varying the height of the impingement channel was examined using spatially resolved external wall temperatures obtained from both experiments and simulations. A one-dimensional heat transfer analysis was used to derive the average internal heat transfer coefficients from the experimental results. Both experiments and simulations showed good agreement between area averaged cooling effectiveness and impingement heat transfer coefficients. The cooling effectiveness and heat transfer coefficients peaked for an impingement channel height of around three impingement hole diameters. However, the heat transfer coefficients were more sensitive than the overall effectiveness to the changes in height of the impingement channel.

“…The segregated pressure-based SIMPLE algorithm was used to solve the steady-state Reynolds-averaged Navier-Stokes (RANS) and energy equations using the SST k-x turbulence model [39] for closure with second-order spatial discretization schemes. The SST k-x model was chosen because it has shown reasonable agreement with experimental results in turbomachinery applications [8,12,18,40,41].…”

Section: Computational Methodologymentioning

confidence: 99%

Conjugate Heat Transfer Measurements and Predictions of a Blade Endwall With a Thermal Barrier Coating

Mensch

Journal of Turbomachinery

Craven

2014

Multiple thermal protection techniques, including thermal barrier coatings (TBCs), internal cooling and external cooling, are employed for gas turbine components to reduce metal temperatures and extend component life. Understanding the interaction of these cooling methods, in particular, provides valuable information for the design stage. The current study builds upon a conjugate heat transfer model of a blade endwall to examine the impact of a TBC on the cooling performance. The experimental data with and without TBC are compared to results from conjugate computational fluid dynamics (CFD) simulations. The cases considered include internal impingement jet cooling and film cooling at different blowing ratios with and without a TBC. Experimental and computational results indicate the TBC has a profound effect, reducing scaled wall temperatures for all cases. The TBC effect is shown to be more significant than the effect of increasing blowing ratio. The computational results, which agree fairly well to the experimental results, are used to explain why the improvement with TBC increases with blowing ratio. Additionally, the computational results reveal significant temperature gradients within the endwall, and information on the flow behavior within the impingement channel.