Session: 13-06 - Internal and External Flows

Paper Number: 124040

124040 - Scale Cooling -- A Novel Fractal Cooling Structure for Turbine Vanes 

A novel turbine cooling vane based on fractal cooling channels has been proposed, utilizing additive manufacturing to realize complex structures. In this work, fractal cooling structure is applied to the first stage guide vane of a heavy-duty gas turbine, and it is compared with the prototype cooling structure of the vane through experiments and simulations.

In the experimental study, two 0.7-fold scaled models of the vanes were manufactured using nickel based alloy additive manufacturing. Infrared testing was conducted using a 1000 ℃ hot wind tunnel to obtain the comprehensive cooling efficiency distribution of the leading edge and pressure side at different temperature ratios and cold air flow rates. The simulation analysis used three-dimensional conjugate heat transfer analysis and finite element method to evaluate the overall cooling efficiency and thermal stress of two vanes. In further simulation, a detailed analysis was conducted on the changes in cooling efficiency at various inlet pressure of cooling air.

The additive manufacturing process of the test vane has verified that the novel fractal cooling structure has good machinability. The reasonably designed shape and diameter of the fractal channel can prevent metal powder blockage. Experimental research shows that under the same cold air flow rate, the comprehensive cooling efficiency of the novel fractal cooling structure blade is improved by 0.05~0.15 compared to the prototype structure. The novel fractal cooling structure blade eliminates temperature non-uniformity and high temperature zone at the leading edge. Simulation analysis shows that the overall cooling efficiency improvement and temperature uniformity characteristics obtained by conjugate heat transfer simulations are consistent with the experimental results. The novel vane requires less cooling air at the same cooling supply pressure but still provides a higher cooling efficiency. When the cooling air pressure decreases, the novel fractal cooling structure has a more significant improvement in cooling efficiency, which can obviously better prevent the backflow of hot gas. Under all comparative conditions, the thermal stress level of the novel fractal cooling structure is comprehensively superior to that of prototype cooling structure.

Presenting Author: Zhongran Chi Shanghai Jiao Tong University

Presenting Author Biography: CHI Zhongran, PhD, associate professor and doctoral supervisor in School of Mechanical Engineering, Shanghai Jiao Tong University. From 2005 to 2011, he studied in Harbin Institute of Technology (Bachelor and Master's degrees). In 2014, he graduated from Tsinghua University (PhD). His research interest is aerothermodynamics of turbomachinery, including multidisciplinary optimization theory of gas turbine HGP components, fault diagnostics of turbine components, etc.

Authors:

Zhongran Chi Shanghai Jiao Tong University
Longfei Wang Nanjing University of Aeronautics and Astronautics