Session: 12-10 Film Cooling with Thermal Barrier Coatings

Paper Number: 82769

82769 - Crossflow Effect on Heat Transfer and Flow Characteristics of Simplified Double Wall Cooling Structure  

Double wall cooling, composed of internal impingement cooling and external film cooling, is regarded as the most advanced cooling technology of modern gas turbines. The internal cooling is always confronted with crossflow effect, so this paper aims to reveal the conjugate heat transfer characteristics of double wall cooling under different crossflow configurations by solving steady three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations.

In this study, a simplified flat plate of double wall cooling model is used. Impingement holes at 90 degree and film holes at 35 degrees are staggered, and they have the same diameter D. The hole pitch for them are 5D along both streamwise and spanwise direction. The thickness of film plate and impingement plate are 3D, as well as the impingement distance. The grid independence verification determines that the final grid used for calculation is 7.61 million, and the turbulence model validation determines that the SST k-ω is used for calculation. The cooling performance of 0%, 25%, 50% and 75% four different crossflow mass flow ratio (CMFR) are compared, and the corresponding film blowing ratio are 2, 1.5, 1, 0.5 respectively. In addition, the influence of film plate thermal conductivity is also taken into consideration.

The calculated results show that the CMFR has a certain influence on the uniformity of blowing ratio for each film hole. When CMFR is 25%, the non-uniformity coefficient of film flow is the smallest, meaning that the distribution of film flow is the most uniform. From the overall valuation, the overall cooling effectiveness decreases with the increase of CMFR over the ranging from 0%-75%, and the Nusselt number of impingement target surface is decreased with the increase of CMFR over the ranging from 0.25 to 0.75. As for the thermal conductivity, it is found that the overall cooling effectiveness increased with the increase of thermal conductivity under all crossflow configurations.

Presenting Author: Juan He Xi'An Jiaotong University

Presenting Author Biography: Juan He is a Ph.D. candidate at Shaanxi Engineering Laboratory of Turbomachinery and Power Equipment, Institute of Turbomachinery, Xi’an Jiaotong University, China, under the supervision of Associate Prof. Qinghua Deng. Her research topic is focused on the aerothermodynamics in gas turbines, especially the impingement cooling research

Authors:

Juan He Xi'An Jiaotong University
Qinghua DENG Xi'An Jiaotong University
Kun Xiao Xi'An Jiaotong University
Zhenping Feng Xi'An Jiaotong University