Film Cooling Performance in a Transonic High-pressure Vane: Decoupled Simulation and Conjugate Heat Transfer Analysis (original) (raw)
Related papers
2003
The demand for the reduction of aero-engines weight and improvement of fuel consumption remains high for the purpose of reducing CO2. Therefore the turbine blade cooling air of the aero-engines reduces relatively and the turbine specification achieves a high pressure ratio with fewer number of stage i.e. highly-loaded. Advanced cooling technologies applied for high loaded turbines have been earnestly investigated. High performance cooling methods and accurate estimation of heat transfer around airfoils are requested to improve turbine vanes and blades’ life. In this study, high speed cascade tests with typical high loaded transonic turbine vane and blade have been conducted to investigate the flow field, the heat transfer and the film cooling effectiveness around blade surface. NOMENCLATURE A Area C Concentration of a tracer M Mach number or mass flux ratio T Temperature U Velocity p Pressure q Net heat transfer flux Heat transfer coefficient f Film cooling effectiveness Ratio of sp...
A Three-Dimensional Coupled Internal/External Simulation of a Film-Cooled Turbine Vane
Journal of Turbomachinery, 2000
A three-dimensional Navier–Stokes simulation has been performed for a realistic film-cooled turbine vane using the LeRC-HT code. The simulation includes the flow regions inside the coolant plena and film cooling holes in addition to the external flow. The vane is the subject of an upcoming NASA Lewis Research Center experiment and has both circular cross-sectional and shaped film cooling holes. This complex geometry is modeled using a multiblock grid, which accurately discretizes the actual vane geometry including shaped holes. The simulation matches operating conditions for the planned experiment and assumes periodicity in the spanwise direction on the scale of one pitch of the film cooling hole pattern. Two computations were performed for different isothermal wall temperatures, allowing independent determination of heat transfer coefficients and film effectiveness values. The results indicate separate localized regions of high heat flux in the showerhead region due to low film eff...
Investigation of the Heat Transfer in High Temperature Gas Turbine Vanes
Volume 4: Heat Transfer; Electric Power, 1987
The demand for higher efficiency, higher temperature industrial gas turbines used for the combined cycle plants has increased. The key technology of such high-temperature gas turbines with a turbine inlet temperature of 1300°C is the development of reliable air-cooled turbine vanes and blades. The life prediction of such air-cooled turbine vanes is strongly dependent on an accurate prediction of the metal temperature. The problem of temperature prediction is essentially one of obtaining the convective heat transfer boundary conditions on the external and internal surfaces of the vane. In this paper, typical heat transfer data which are indispensable for the analysis, are presented. Improvement of the temperature prediction accuracy within 25°C, the final goal, is sought by feeding the discrepancy between the cascade test and the analysis back into the fundamental heat transfer tests. NOMENCLATURE D leading edge diameter D = diameter of cylindrical target surface d = impingement hole diameter d = pin fin diameter de = equivalent hydraulic diameter G = flow rate H = pin fin height h = heat transfer coefficient M = mass flux ratio, PcUc/PcoUw Nu = Nusselt number P = impingement hole spacing p = pin spacing Pr = Prandtl number R = equivalent radius of target area of one impingement jet Re = Reynolds number S = equivalent 2-dimensional slot width T = temperature U = velocity x = surface distance from leading edge x = distance from the film cooling hole Z = distance between impingement plate and target plate qf film cooling effectiveness p = density T = turbulence intensity Subscripts aw adiabatic wall c = cooling air c = crossflow g = gas i = impingement = mainstream INTRODUCTION
Conjugate Heat Transfer Effects on a Realistic Film-Cooled Turbine Vane
2003
A conjugate heat transfer solver has been developed and applied to a realistic film-cooled turbine vane for a variety of blade materials. The solver used for the fluid convection part of the problem is the Glenn-HT general multiblock heat transfer code. The solid conduction module is based on the Boundary Element Method (BEM), and is coupled directly to the flow solver. A chief advantage of the BEM method is that no volumetric grid is required inside the solid -only the surface grid is needed. Since a surface grid is readily available from the fluid side of the problem, no additional gridding is required. This eliminates one of the most time consuming elements of the computation for complex geometries. Two conjugate solution examples are presented -a high thermal conductivity Inconel nickel-based alloy vane case and a low thermal conductivity silicon nitride ceramic vane case. The solutions from the conjugate analyses are compared with an adiabatic wall convection solution. It is found that the conjugate heat transfer cases generally have a lower outer wall temperature due to thermal conduction from the outer wall to the plenum. However, some locations of increased temperature are seen in the higher thermal conductivity Inconel vane case. This is a result of the fact that film cooling is a two-temperature problem, which causes the direction of heat flux at the wall to change over the outer surface. Three-dimensional heat conduction in the solid allows for conduction heat transfer along the vane wall in addition to conduction from outer to inner wall. These effects indicate that the conjugate heat transfer in a complicated geometry such as a film-cooled vane is not governed by simple one-dimensional conduction from the vane surface to the plenum surface, especially when the effects of coolant injection are included.
Conjugate Heat Transfer in a Turbine Vane and Thermal Barrier Coating
Proceedings of the 5th International Conference of Fluid Flow, Heat and Mass Transfer (FFHMT'18), 2018
The high pressure (HP) turbine is subject to high temperature inlet flow non-uniformities resulting from the combustion chamber. This paper presents a new fluid-solid interface treatment for conjugate heat transfer (CHT) applied to two configurations of interest in the design of high pressure turbine blades to accurately estimate the temperature in the blade. The computational fluid dynamics (CFD) solver elsA, and a solid conduction solver, Zset, both developed at the French Aerospace Lab (ONERA), have been used for all simulations. Two problems, typical of a high pressure turbine, are studied: (1) a turbine vane with a hot-streak to present the validity of the coupling process during the design phase of a blade turbine. Results will be compared to CFD only simulation and experimental data. (2) A conjugate heat transfer simulation with a thermal barrier coating (TBC) on the solid side has also been studied. The TBC is known to better withstand high temperature but taking it into account in a CHT simulation is really difficult because of the strong fluid-solid interaction. This two configurations have really different characteristics in a coupled problem based on the Biot number, and the coupled methodology presented attempt to solve both of them using a Dirichlet-Robin interface condition.
Heat transfer and film-cooling for the endwall of a first stage turbine vane
International Journal of Heat and Mass Transfer, 2005
Secondary flows that result in turbomachines from inherent pressure gradients in airfoil passages, are the main contributors to aerodynamic losses and high heat transfer to the airfoil endwalls. The endwalls present a challenge to durability engineers in maintaining the integrity of the airfoils. One means of preventing degradation in the turbine is to film-cool components whereby coolant is extracted from the compressor and injected through small cooling holes in the airfoil surfaces. In addition to film-cooling, leakage flows from component interfaces, such as the combustor and turbine, can provide cooling in localized areas but also provide a change to the inlet boundary condition to the passage. This paper presents measurements relevant to the endwall region of a vane, which indicate the importance of considering the inlet flow condition.
ASME SHTC, 2019
This paper describes a numerical investigation to study the effect of injecting mist (tiny water droplets, micrometers in size) into the cooling airstream to cool down gas turbine vanes. In this study, the conjugate heat transfer method is employed which consists of the simulation of the air/mist fluid flow inside and outside the vanes as well as the heat conduction through the vane body. The complete 3-D vane with internal cooling passages and external film cooling holes on the surface is simulated in a rotational periodic sector. The discrete phase model (DPM) is used to simulate and track the evaporation and movement of the tiny water droplets. The effects of different parameters such as the mist/air ratio (10-20%) and the mist droplets size (20-50µm) on mist cooling enhancement are investigated. The results show that by using a mist/air ratio of 10%, 15%, and 20% with 20 μm droplets size, on the pressure side, a maximum wall temperature reduction of 250 K, 340 K, and 450 K respectively can be achieved. On the suction side, the corresponding maximum wall temperature reductions are 160 K, 260 K, and 360 K, respectively. Using larger droplets of 50µm did not achieve better cooling enhancement because the droplets were rushed far away from the surface by the acceleration through the film cooling holes. Using the uniform droplet size distribution provides noticeably better cooling enhancement in the first 40% of the vane's height (from the shroud) than the non-uniform droplet size distribution (Rosin-Rammler Distribution) does.
Energies, 2018
The aim of this paper is to numerically investigate cooling performances of a non-film-cooled turbine vane coated with a thermal barrier coating (TBC) at two turbulence intensities (Tu = 8.3% and 16.6%). Computational fluid dynamics (CFD) with conjugate heat transfer (CHT) analysis is used to predict the surface heat transfer coefficient, overall and TBC effectiveness, as well as internal and average temperatures under a condition of a NASA report provided by Hylton et al. [NASA CR-168015]. The following interesting phenomena are observed: (1) At each Tu, the TBC slightly dampens the heat transfer coefficient in general, and results in the quantitative increment of overall cooling effectiveness about 16-20%, but about 8% at the trailing edge (TE). (2) The protective ability of the TBC increases with Tu in many regions, that is, the leading edge (LE) and its neighborhoods on the suction side (SS), as well as the region from the LE to the front of the TE on the pressure side (PS), because the TBC causes the lower enhancement of the heat transfer coefficient in general at the higher Tu. (3) Considering the internal and average temperatures of the vane coated with two different TBCs, although the vane with the lower thermal conductivity protects more effectively, its role in the TE region reduces more significantly. (4) For both TBCs, the increment of Tu has a relatively small effect on the reduction of the average temperature of the vane.
Experimental and Computational Comparisons of Fan-Shaped Film Cooling on a Turbine Vane Surface
Journal of turbomachinery, 2006
The flow exiting the combustor in a gas turbine engine is considerably hotter than the melting temperature of the turbine section components, of which the turbine nozzle guide vanes see the hottest gas temperatures. One method used to cool the vanes is to use rows of film-cooling holes to inject bleed air that is lower in temperature through an array of discrete holes onto the vane surface. The purpose of this study was to evaluate the row-by-row interaction of fan-shaped holes as compared to the performance of a single row of fan-shaped holes in the same locations. This study presents adiabatic film-cooling effectiveness measurements from a scaled-up, two-passage vane cascade. High-resolution film-cooling measurements were made with an infrared camera at a number of engine representative flow conditions. Computational fluid dynamics predictions were also made to evaluate the performance of some of the current turbulence models in predicting a complex flow such as turbine film-cooling. The renormalization group (RNG) k-turbulence model gave a closer prediction of the overall level of film effectiveness, while the v 2-f turbulence model gave a more accurate representation of the flow physics seen in the experiments.
Energy Procedia, 2014
Gas turbine performance improvement is strictly linked to the attainment of higher maximum temperature, hence heat load management becomes an essential activity. This paper presents a decoupled procedure aimed to predict cooling performances and metal temperatures of gas turbine blades and nozzles: needed inputs are evaluated by different tools (CFD, in-house fluid network solver, thermal FEM). The procedure is validated on two different test cases: an internally cooled vane (Hylton et al.[1]), and an internally and film cooled vane (Hylton et al.[2]). Metal temperature and adiabatic effectiveness distributions are compared against experimental data and results from a fully 3D coupled CHT CFD analysis.