Investigation of the Film-Cooling Performance of 2.5D Braided Ceramic Matrix Composite Plates with Preformed Hole

Chenwei Zhao,Zecan Tu,Junkui Mao

doi:10.3390/aerospace8040116

Abstract

The film-cooling performance of a 2.5D braided ceramic matrix composite (CMC) plate with preformed holes was numerically studied. Four numerical models containing braided structures were established: one model with film-cooling holes preformed through fiber extrusion deformation (EP-Hole), one model with film-cooling holes directly woven through fibers (WP-Hole), and two models with directly drilled holes (DP-Hole1,2). Besides, the influence of the ratio between the equivalent thermal conductivities on the axial and radial directions of fiber Kr was investigated. The results show that the preformed holes have better performance in controlling the thermal gradient with the increase of Kr. The maximum thermal gradient around the DP-Hole is significantly higher than that of the WP-Hole and EP-Hole, and the maximum relative variation reaches 123.3%. With Kr increasing from 3.32 to 13.05, the overall cooling effectiveness on the hot-side wall decreases for all models, by about 10%. Compared with the traditional drill method, the new preformed film-cooling hole studied in this paper can reduce the temperature and the thermal gradient in the region around the holes.

Highlights

With the continuous increase of the thermal load on the hot components of advanced propulsion systems [1,2], the temperature resistance requirements for the materials of the hot components have been continuously improved
The braided fibers and matrix of ceramic matrix composite (CMC) could be oxidized in high-temperature environments, and the literature [11] shows that the oxidation rate of CMC increases with the increase of environmental temperature, especially in ultra-high temperature environments (>1500 ◦C)
Unal’s [16] research on SiC/SiC composites showed that after SiC/SiC composite samples were exposed to a dry oxygen environment at 1400 ◦C for 50 h, the fracture stress of the oxidized specimens decreased by about 50%

Summary

Introduction

With the continuous increase of the thermal load on the hot components of advanced propulsion systems [1,2], the temperature resistance requirements for the materials of the hot components have been continuously improved. Braided ceramic matrix composite (CMC) has excellent heat resistance and mechanical properties, which makes it a popular candidate material for high-temperature components of advanced propulsion systems [3,4,5,6,7]. The GE Company’s research [15] showed that the ultimate strength degradation of CMC reinforced with Hi-Nicalon fibers was less than 10% after being exposed to the air at 1200 ◦C for 4000 h, while the ultimate strength degraded 30% after exposure to air at 1315 ◦C for 1000 h. The CMC components still need cooling structures to protect them from oxidation

Methods

Results

Conclusion