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Development of a Suitable Computational Conjugate Heat Transfer Algorithm to Analyze Turbine Blade Internal Cooling

Sajadi, Ali | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54130 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud
  7. Abstract:
  8. Nowadays, the study of flow and heat transfer in turbine engines has become critical due to their increasing use and importance in various engineering industries. The critical issue of blade burning in the first row of turbine’s blades illuminates the critical roles of numerical and experimental activities in reducing these undesirable effects. Since blade cooling is directly related to the secondary air system, one important issue in blade burning research is to utilize the conjugate heat transfer approach. As Known, an increase of about 1% in the mass flow of air entering into the secondary air system would cause an increase of about 0.5% in the engine specific fuel consumption (SFC), which can increase the engine operating costs by about 0.25%. Due to the high complexity of the secondary air system in the turbine engine as a power supply for the vane cooling flow and the other equipment in the hot section of engine, it’s highly important to reduce the computational cost of related analyzes including the vane cooling analysis via sticking on the semi-analytical empirical solution methods. A review of past literature shows that there are less efforts to couple two professional commercial software of which one is used to study the external heat and flow analysis via using the CFD methods and the other one relies on the analytical-empirical correlations to calculate the internal flow and heat transfer analysis. The purpose of this research is to use such powerful software together as a practice to improve the reliability in solution and reduce the computational cost. This study develops a conjugate heat transfer analysis algorithm in which the analyses of external flow and conduction heat transfer in the turbine blade are performed using the commercial CFD software and the heat transfer analysis of the turbine blade cooling channels is conducted using the Flowmaster commercial software. In the external flow calculation, we examine various turbulence models. In the present study, NASA-C3X blade, which benefits from 10 circular channels as the internal cooling channels, is used to validate the results of the developed conjugate heat transfer algorithm. In the first part, the 3D solution is simulated in full scale using various turbulence models. Also, according to the conjugate heat transfer algorithm, one-dimensional network commercial software is used to simulate the heat transfer of cooling channels and the obtained solution is coupled with the resulting 3D CFD solution of external flow. The results show that they are in good agreement with the experimental data and that there is substantial reduction in computational time while obtaining suitable accuracy. The study shows that the computational time of the present semi-analytical-empirical approach is reduced by about one-seventh compared to the equivalent 3D CFD method if one uses the full-scale simulation. The simulation accuracy is good enough to calculate the aerodynamic coefficients. Furthermore, the thermal parameter calculations are relatively reliable because of using the 1D network calculation in the internal flow calculation part. To improve the accuracy of thermal parameters prediction, it’s necessary to use more accurate correlated relations
  9. Keywords:
  10. Turbine Cooling ; Gas Turbines ; Conjugate Heat Transfer ; Semi-Analytical Solution ; Experimental Investigation ; Turbine Blades

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