THERMAL BARRIER COATING AND TURBULENCE INTENSITY EFFECTS ON LEADING EDGE COOLING USING CONJUGATE HEAT TRANSFER ANALYSIS

2017 ◽  
Vol 41 (2) ◽  
pp. 249-263 ◽  
Author(s):  
Prasert Prapamonthon ◽  
Huazhao Xu ◽  
Zhaoqing Ke ◽  
Wenshuo Yang ◽  
Jianhua Wang

This is a numerical study of thermal barrier coating (TBC) and turbulence on leading edge (LE) cooling of a guide vane. Numerical results were carried out using 3D CFD with conjugate heat transfer analysis. Important phenomena were revealed. (1) TBC is effective in the LE region especially when free stream turbulence (Tu) increases. (2) At each Tu, TBC near the hub of the vane provides the most effective protection and at the highest Tu, TBC improves overall cooling effectiveness there by about 25%. (3) Near the exits of film hole, TBC may have negative effect, because of heat transfer impedance from the solid structure into the mixing fluid between mainstream and cooling air emitted from film holes.

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 1000 ◽  
Author(s):  
Prasert Prapamonthon ◽  
Soemsak Yooyen ◽  
Suwin Sleesongsom ◽  
Daniele Dipasquale ◽  
Huazhao Xu ◽  
...  

Author(s):  
Yuzhang Wang ◽  
Jiali Li ◽  
Hongzhao Liu ◽  
Yiwu Weng

Due to different preparation processes and long term operation, the micro structure of thermal barrier coating is different. The different micro structures have great effect on the thermal insulation properties of thermal barrier coatings and the conjugate heat transfer between the cooling film and thermal barrier coatings. In this work, different micro structures of thermal barrier coating were reconstructed using the scanning electron microscopy (SEM) images of two kinds of real thermal barrier coatings. The developed numerical calculation program based on the lattice Boltzmann method (LBM) was used to analyze the conjugate flow field and heat transfer between cooling film and porous thermal barrier coatings. The results show that the micro structures of thermal barrier coatings have a great influence on the stability of the surface film. Weak spatial variations in fluid velocity appear over the coating surface. The spatial variations in velocity over the layered coatings are larger because of its rough surfaces. The ratio of the vertical velocity to the bulk flow velocity can reach 2.5%. There is obvious vortex flow at the interface of coatings and cooling film, and weak flow in the interior perpendicular pores of the columnar coatings.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
G. L. Arunkumar ◽  
Balachandra P. Shetty ◽  
R. K. Mishra

Abstract This paper presents a computational method to investigate cooling performance of NASA-C3X cascade vane coated with thermal barrier coating (TBC), for which experimental data are available. The vane was cooled internally by air flows through radially oriented 10 channels. A three-dimensional conjugate heat transfer simulation has been performed which allows the conduction-convection on metal vane by eliminating need of multiple boundary solutions. The predicted aerodynamic and thermal loads with the effect of turbulent intensity is found to be good agreement with experimental data and inclusion of TBC leads to quantitative reduction in vane metal temperature.


2020 ◽  
Vol 0 (0) ◽  
Author(s):  
G. L. Arunkumar ◽  
Balachandra P. Shetty ◽  
R. K. Mishra

AbstractThis paper presents a computational method to investigate cooling performance of NASA-C3X cascade vane coated with thermal barrier coating (TBC), for which experimental data are available. The vane was cooled internally by air flows through radially oriented 10 channels. A three-dimensional conjugate heat transfer simulation has been performed which allows the conduction-convection on metal vane by eliminating need of multiple boundary solutions. The predicted aerodynamic and thermal loads with the effect of turbulent intensity is found to be good agreement with experimental data and inclusion of TBC leads to quantitative reduction in vane metal temperature.


Author(s):  
F. Montomoli ◽  
A. D’Ammaro ◽  
S. Uchida

Conjugate Heat Transfer studies are a common method to predict the thermal loading in high pressure nozzles. Despite the accuracy of nowadays tools, it is not clear how to include the uncertainties associated to the turbulence level, the temperature distribution or the thermal barrier coating thickness in the numerical simulations. All these parameters are stochastic even if their value is commonly assumed to be deterministic. For the first time, in this work a stochastic analysis is used to predict the metal temperature in a real high pressure nozzle. The domain is the complete high pressure nozzle of F-type Mitsubishi Heavy Industries gas turbine with impingement, film and trailing edge cooling. The stochastic variations are included by coupling Uncertainty Quantification Methods and Conjugate Heat Transfer. Two Uncertainty Quantification methods have been compared: a Probabilistic Collocation Method (PCM) and a Stochastic Collocation Method (SCM). The stochastic distribution of thermal barrier coating thickness, used in the simulations, has been measured at the midspan. A Gaussian distribution for the turbulence intensity and hot core location has been assumed. By using PCM and SCM, the probability to obtain specific metal temperature at midspan is evaluated. The two methods predict the same distribution of temperature with a maximum difference of 0.6% and the results are compared with the experimental data measured in the real engine. The experimental data are inside the uncertainty band associated to the CFD predictions except near at the trailing edge on the pressure side. This work shows that one of the most important parameters affecting the metal temperature uncertainty is the pitch-wise location of the hot core. Assuming a probability distribution for this location, with a standard deviation of 1.7 degrees, the metal temperature at midspan can change up to 30%. The impact of turbulence level and thermal barrier coating thickness is one order of magnitude less important.


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