Numerical simulation of turbine internal cooling and conjugate heat transfer problems with Ra-based turbulance models

Download
2012
Görgülü, İlhan
The present study considers the numerical simulation of the different flow characteristics involved in the conjugate heat transfer analysis of an internally cooled gas turbine blade. Conjugate simulations require full coupling of convective heat transfer in fluid regions to the heat diffusion in solid regions. Therefore, accurate prediction of heat transfer quantities on both external and internal surfaces has the uppermost importance and highly connected with the performance of the employed turbulence models. The complex flow on both surfaces of the internally cooled turbine blades is caused from the boundary layer laminar-to-turbulence transition, shock wave interaction with boundary layer, high streamline curvature and sequential flow separation. In order to discover the performances of different turbulence models on these flow types, analyses have been conducted on five different experimental studies each concerned with different flow and heat transfer characteristics. Each experimental study has been examined with four different turbulence models available in the commercial software (ANSYS FLUENT13.0) to decide most suitable RANS-based turbulence model. The Realizable k-ε model, Shear Stress Transport k-ω model, Reynolds Stress Model and V2-f model, which became increasingly popular during the last few years, have been used at the numerical simulations. According to conducted analyses, despite a few unreasonable predictions, in the majority of the numerical simulations, V2-f model outperforms other first-order turbulence models (Realizable k-ε and Shear Stress Transport k-ω) in terms of accuracy and Reynolds Stress Model in terms of convergence.

Suggestions

Numerical Analysis of Nanofluids Convective Heat Transfer with Euler Euler and Mixture Model Approaches
Sert, İsmail Ozan; Sezer Uzol, Nilay; Güvenç Yazıcıoğlu, Almıla; Kakaç, Sadık (2014-06-13)
Forced convection heat transfer characteristics of Al2O3/water nanofluid are investigated numerically by using mixture model two-phase flow approach with Fluent software. The initially hydro-dynamically fully developed laminar nanofluid flow simulations are performed with different nanoparticle volume fractions. The effects of thermal conductivity and viscosity models on heat transfer enhancements are carried out for constant heat flux boundary condition. As a result, the heat transfer coefficient results o...
3 D time accurate CFD simulations of wind turbine rotor flow fields
Tonkal, Ozan Çağrı; Pehlivan, Sercan; Sezer Uzol, Nilay; İşler, Veysi (American Institute of Aeronautics and Astronautics Inc.(AIAA); 2006-01-12)
This paper presents the results of three-dimensional and time-accurate Computational Fluid Dynamics (CFD) simulations of the flow field around the National Renewable Energy Laboratory (NREL) Phase VI horizontal axis wind turbine rotor. The 3-D, unsteady, parallel, finite volume flow solver, PUMA2, is used for the simulations. The solutions are obtained using unstructured moving grids rotating with the turbine blades. Three different flow cases with different wind speeds and wind yaw angles are investigated:...
Improving flow structure and natural convection within fin spacings of plate fin heat sinks
Özet, Mehmet Erdem; Tarı, İlker; Department of Mechanical Engineering (2015)
The main objectives of this thesis are to numerically investigate the previously observed recirculation zones and longitudinal vortices that occur in low fin height plate finned horizontal heat sinks and to improve the flow structures and heat transfer in these zones using various approaches with the help of simulations performed using commercially available CFD software. The approaches used for improvements are replacing the outer most fins with higher ones, introducing gaps on the length of the fins in va...
Numerical Analysis of Phase Change Material Characteristics Used in a Thermal Energy Storage Device
Bonyadi, Nima; Somek, Suleyman Kazim; Ozalevli, Cemil Cihan; Baker, Derek Keıth; Tarı, İlker (2018-01-01)
In this study, a numerical analysis is performed to investigate the freezing process of phase change materials (PCM) in a predesigned thermal energy storage (TES) device. This TES device is integrated with a milk storage cooling cycle operating under predefined practical conditions. Using this cooling unit, 100 litres of milk is kept cool at 4 degrees C for 48 hours before it is collected. A 2-D model of the TES device is developed in COMSOL Multiphysics to analyze the phase change performance of water-base...
Heat Transfer for the Film Cooled Vane of a 1 1 2 Stage High Pressure Transonic Turbine Part I Experimental Configuration and Data Review With Inlet Temperature Profile Effects
Kahveci, Harika Senem; MATHISON, RANDALL; DUNN, MICHAEL (2011-01-01)
This paper investigates the vane airfoil and inner endwall heat transfer for a full-scale turbine stage operating at design corrected conditions under the influence of different vane inlet temperature profiles and vane cooling flow rates. The turbine stage is a modern 3-D design consisting of a cooled high-pressure vane, an un-cooled high-pressure rotor, and a low-pressure vane. Inlet temperature profiles (uniform, radial and hot streaks) are created by a passive heat exchanger and can be made circumferenti...
Citation Formats
İ. Görgülü, “Numerical simulation of turbine internal cooling and conjugate heat transfer problems with Ra-based turbulance models,” M.S. - Master of Science, Middle East Technical University, 2012.