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

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Amy Mensch ◽  
Karen A. Thole ◽  
Brent A. Craven
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Thermal Protection ◽  
Flow Behavior ◽  
Design Stage ◽  
Thermal Barrier ◽  
Transfer Model ◽  
Computational Results ◽  
Blowing Ratio ◽  
The Impact

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.

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

2014 ◽  
Author(s):  
Amy Mensch ◽  
Karen A. Thole ◽  
Brent A. Craven
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Thermal Protection ◽  
Flow Behavior ◽  
Design Stage ◽  
Thermal Barrier ◽  
Transfer Model ◽  
Computational Results ◽  
Blowing Ratio ◽  
The Impact

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 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.

Conjugate heat transfer modeling of a turbine vane endwall with thermal barrier coatings

2019 ◽  
Vol 123 (1270) ◽  
pp. 1959-1981 ◽  
Author(s):  
Xing Yang ◽  
Zhenping Feng ◽  
Terrence W. Simon
Keyword(s):  
Heat Transfer ◽  
Thermal Barrier Coatings ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Thermal Protection ◽  
Design Stage ◽  
Thermal Barrier ◽  
Cooling Effectiveness ◽  
Barrier Coatings ◽  
Turbine Vane

ABSTRACTAdvanced cooling techniques involving internal enhanced heat transfer and external film cooling and thermal barrier coatings (TBCs) are employed for gas turbine hot components to reduce metal temperatures and to extend their lifetime. A deeper understanding of the interaction mechanism of these thermal protection methods and the conjugate thermal behaviours of the turbine parts provides valuable guideline for the design stage. In this study, a conjugate heat transfer model of a turbine vane endwall with internal impingement and external film cooling is constructed to document the effects of TBCs on the overall cooling effectiveness using numerical simulations. Experiments on the same model with no TBCs are performed to validate the computational methods. Round and crater holes due to the inclusion of TBCs are investigated as well to address how film-cooling configurations affect the aero-thermal performance of the endwall. Results show that the TBCs have a profound effect in reducing the endwall metal temperatures for both cases. The TBC thermal protection for the endwall is shown to be more significant than the effect of increasing coolant mass flow rate. Although the crater holes have better film cooling performance than the traditional round holes, a slight decrement of overall cooling effectiveness is found for the crater configuration due to more endwall metal surfaces directly exposed to external mainstream flows. Energy loss coefficients at the vane passage exit show a relevant negative impact of adding TBCs on the cascade aerodynamic performance, particularly for the round hole case.

A Conjugate Heat Transfer and Thermal Stress Analysis of Film-Cooled Superalloy With Thermal Barrier Coating

2020 ◽  
Author(s):  
Xiaohu Chen ◽  
Jiao Li ◽  
Yun Long ◽  
Yuzhang Wang ◽  
Shilie Weng ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Leading Edge ◽  
Cooling Effect ◽  
Thermal Barrier ◽  
Blowing Ratio ◽  
Cooling Hole ◽  
Cooling Tube

Abstract A conjugate heat transfer study is carried out to obtain temperature and thermal stress field of a film-cooled superalloy with multi-layer thermal barrier coatings (TBCs). The aim is to understand the effects of the blowing ratio and ceramic top coating (TC) thickness on temperature and thermal stress which have an influence on component reliability and life. Results reveal that the distribution of film cooling effectiveness gets more uniform as TC thickness decrease because thick TC with low thermal conductivity prevents heat conduction in the axial and spanwise directions. In the upstream of the film cooling hole, the cooling effect is enhanced nonlinearly with the increase of the blowing ratio since the flow separation in the cooling tube affects the heat transfer enhancement. The insulation performance is improved by about 10 K for every 0.1D increase in TC thickness and the cooling effect is improved by about 20 K when the blowing ratio is increased from 0.5 to 1.0 at the leading edge of the film-cooling tube. The influence of jet lift-off and hotgas entrainment on the insulation effect is greater than TC thickness. The stress is concentrated at the leading edge of the film cooling hole and interfaces of TBCs. The maximum Von-Mises stress (761 MPa) on the interfaces is not at the leading or trailing sides of the film-cooling tube, it is about ± 45° from the centerline of the BC/SUB interface. The debonding stress at TC/BC interface and BC/SUB interface are about 26 MPa and 175 MPa respectively. The normal stress near the film-cooling tube on the BC/SUB interface is 5 – 7 times the one at TC/BC interface. Therefore, the interface crack is more likely to initiate at the BC/SUB interface, and the crack may keep growing and cause the spalling of TBC.

scholarly journals Conjugate heat transfer study of the impact of ‘thermo-swing’ coatings on internal combustion engines heat losses

2020 ◽  
pp. 146808742096061
Author(s):  
Alberto Broatch ◽  
Pablo Olmeda ◽  
Xandra Margot ◽  
Johan Escalona
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Conjugate Heat Transfer ◽  
Internal Combustion Engines ◽  
Internal Combustion ◽  
Heat Losses ◽  
Transfer Model ◽  
Insulation Material ◽  
Engine Efficiency ◽  
The Impact

To comply with the very strict emissions regulation the automotive industry is succeeding in developing ever more efficient engines, and there is scope for more improvements. In this regard, some investigations have suggested that insulating the combustion chamber walls of an internal combustion engine (ICE) yield low thermal losses. Most of the literature available on this topic presents simplified models that do not allow studying in detail the coating impact on engine efficiency. A more precise approach that consists in the combination of Computational Fluid Dynamics (CFD) and Conjugate Heat Transfer (CHT) simulations is used in this paper to predict the heat losses through the combustion chamber walls of a spark ignition (SI) engine. Two configurations are considered for the single cylinder engine: the metallic case and the same engine with coated piston and cylinder head. The insulation material has a low thermal conductivity ( k[Formula: see text]1.0 W/( mK)). The numerical results are validated by comparison with the results of a 1D heat transfer model and with experimental data for a medium load operation point (3000 rpm −7 bar IMEP). The solutions obtained are analysed in detail in terms of wall temperature distribution and heat transfer. The impact of the coating on the engine efficiency is thus assessed. The CFD-CHT calculations yields very good results in terms of heat transfer prediction during the whole engine cycle.

Thermal Response and Ablation Research of EPDM Thermal Protection Material in Ramjet

2015 ◽  
Vol 1092-1093 ◽  
pp. 534-538
Author(s):  
Xiong Chen ◽  
Hai Feng Xue ◽  
Hua Liang
Keyword(s):  
Heat Transfer ◽  
Heat Load ◽  
Thermal Protection ◽  
Thermal Response ◽  
Transfer Model ◽  
Back Face ◽  
Ground Test ◽  
Simulation Results ◽  
Face Temperature ◽  
Scanning Electron

Thermal protection materials are required to preserve the metal components of motor that suffer severe heat load. The research on thermal response of insulation of ramjet combustion chamber was carried out by the ground test and numerical simulation. During the working time of the ramjet, the back-face temperature of the thermal protection material was measured. The scanning electron microscope of samples was investigated. The calculation of thermo-chemical flow was solved by the CFD software FLUENT to provide the heat load boundary for simulation of heat transfer of EPDM insulation. The heat transfer model was solved by the FEA software ANSYS. Comparison of the temperature profile at the ablating surface between calculation and measurement shows the two results agree with each other. The simulation results can provide the temperature rising trend of insulation in a certain extent.

scholarly journals Conjugate heat transfer performance of stepped lid-driven cavity with Al2O3/water nanofluid under forced and mixed convection

2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Naveen Janjanam ◽  
Rajesh Nimmagadda ◽  
Lazarus Godson Asirvatham ◽  
R. Harish ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mixed Convection ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Interface Temperature ◽  
Transfer Model ◽  
Transfer Performance ◽  
Driven Cavity

AbstractTwo-dimensional conjugate heat transfer performance of stepped lid-driven cavity was numerically investigated in the present study under forced and mixed convection in laminar regime. Pure water and Aluminium oxide (Al2O3)/water nanofluid with three different nanoparticle volume concentrations were considered. All the numerical simulations were performed in ANSYS FLUENT using homogeneous heat transfer model for Reynolds number, Re = 100 to 500 and Grashof number, Gr = 5000, 13,000 and 20,000. Effective thermal conductivity of the Al2O3/water nanofluid was evaluated by considering the Brownian motion of nanoparticles which results in 20.56% higher value for 3 vol.% Al2O3/water nanofluid in comparison with the lowest thermal conductivity value obtained in the present study. A solid region made up of silicon is present underneath the fluid region of the cavity in three geometrical configurations (forward step, backward step and no step) which results in conjugate heat transfer. For higher Re values (Re = 500), no much difference in the average Nusselt number (Nuavg) is observed between forced and mixed convection. Whereas, for Re = 100 and Gr = 20,000, Nuavg value of mixed convection is 24% higher than that of forced convection. Out of all the three configurations, at Re = 100, forward step with mixed convection results in higher heat transfer performance as the obtained interface temperature is lower than all other cases. Moreover, at Re = 500, 3 vol.% Al2O3/water nanofluid enhances the heat transfer performance by 23.63% in comparison with pure water for mixed convection with Gr = 20,000 in forward step.

A Two-Dimensional Conjugate Heat Transfer Model for Forced Air Cooling of an Electronic Device

1989 ◽  
Vol 111 (1) ◽  
pp. 41-45 ◽  
Author(s):  
A. Zebib ◽  
Y. K. Wo
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Electronic Device ◽  
Transfer Problem ◽  
Maximum Temperature ◽  
Transfer Model ◽  
Air Cooling ◽  
Two Dimensional ◽  
Component Design ◽  
Forced Air

Thermal analysis of forced air cooling of an electronic component is modeled as a two-dimensional conjugate heat transfer problem. The velocity field in a constricted channel is first computed. Then, for a typical electronic module, the energy equation is solved with allowance for discontinuities in the thermal conductivity. Variation of the maximum temperature with the average air velocity is presented. The importance of our approach in evaluating possible benefits due to changes in component design and the limitations of the two-dimensional model are discussed.

Conjugate Heat Transfer Analysis on Generic Rim Seal Configurations in Rotor-Stator System

2018 ◽  
Author(s):  
Xingyun Jia ◽  
Liguo Wang ◽  
Qun Zheng ◽  
Hai Zhang ◽  
Yuting Jiang
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Conjugate Heat Transfer ◽  
Heat Transfer Analysis ◽  
Minimum Mass ◽  
Aerodynamic Efficiency ◽  
Axial Clearance ◽  
The Impact

Performance of generic rim seal configurations, axial-clearance rim seal (ACS), radial-clearance rim seal (RCS), radial-axial clearance rim seal (RACS) are compared under realistic working conditions. Conjugate heat transfer analysis on rim seal is performed in this paper to understand the impact of ingestion on disc temperature. Results show that seal effectiveness and cooling effectiveness of RACS are the best when compared with ACS and RCS, the minimum mass flow rate for seal of RACS is 75% of that of RCS, and 34.6% of ACS. Authors compare the disc temperature distribution between different generic rim seal configurations where the RACS seems to be favorable in terms of low disc temperature. In addition, RACS has higher air-cooled aerodynamic efficiency, minimizing the mainstream performance penalty when compared with ACS and RCS. Corresponding to the respective minimum mass flow rate for seal, the air-cooled aerodynamic efficiency of RACS is 23.71% higher than that of ACS, and 12.79% higher than the RCS.

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