Session: 12-03 Endwall Film Cooling

Paper Number: 83159

83159 - Aero-Thermal Analysis of Non-Axisymmetric and Flat Endwalls Under the Operational and Geometrical Uncertainties 

The high thermal loads and strong secondary flows make the aero-thermal design of turbine endwalls a hot research topic in the fields of gas turbines. Non-axisymmetric endwall, as an effective flow control technique, is promising to enhance cascade aerodynamic performance and endwall thermal protection. However, operating in such harsh flow and thermal environments, the turbine endwall, especially for a non-axisymmetric endwall, is extremely susceptible to operational and geometrical uncertainties. Therefore, it is of vital significance to quantitatively assess and compare the aero-thermal performance of non-axisymmetric endwalls and traditional flat endwalls under the propagation of operational and geometrical uncertainties. To resolve this problem, this paper develops an efficient uncertainty quantification method suitable for expensive turbomachinery cases. Using this method, the effects of mainstream operational fluctuations and slot geometrical deviations on an optimized non-axisymmetric endwall and a benchmark flat endwall are quantitatively investigated. The results show that a non-axisymmetric endwall significantly enhances the statistical aero-thermal performance compared to a flat endwall. Specifically, the statistical mean of the total pressure recovery coefficient is increased by 0.15%, and its total pressure recovery coefficient has a probability of 87.4% to be higher than the statistical mean of the flat endwall; the statistical mean of the endwall film cooling effectiveness is enhanced by 49.5%, and the probability of its film cooling efficiency being higher than the statistical mean of the flat endwall reaches 100%; the statistical mean of endwall Nussle number is lowered by 2.9%, and the probability of its Nussle number being lower than the statistical mean of the flat endwall reaches 99.5%. Furthermore, the statistical variance analysis shows that the aero-thermal performance of the regions influenced by secondary flows and the contouring regions of non-axisymmetric endwalls are more sensitive to input uncertainties. Finally, through an in-depth comparison of the extreme performance of these two endwalls due to input uncertainties, the fundamental flow and thermal physics behind the influence of important uncertain parameters on the aero-thermal performance of different endwalls are elucidated. The above research is expected to support the design of more efficient and reliable non-axisymmetric endwalls.

Presenting Author: Zhi Tao Institute of Turbomachinery, Xi’an Jiaotong University

Presenting Author Biography: Zhi Tao is a PhD candidate at Xi'an Jiaotong University, engaged in turbine aerodynamic and heat transfer design and uncertainty quantification.

Authors:

Zhi Tao Institute of Turbomachinery, Xi’an Jiaotong University
Jie Wang Institute of Turbomachinery, Xi’an Jiaotong University
Liming Song Institute of Turbomachinery, Xi’an Jiaotong University
Jun Li Institute of Turbomachinery, Xi’an Jiaotong University