Numerical Investigation of the Heat Transfer and Discharge Coefficient of the Narrow Double Wall Cooling

Abstract A numerical investigation was conducted to explore the heat transfer and discharge characteristics of a narrow double wall cooling configuration. The narrow double wall cooling configuration comprises a row of impingement holes and a row of film holes. Two impingement distances, Z/D = 1 and Z/D = 2, were studied, along with six impingement Reynolds numbers ranging from 5000 to 30000. In addition, the layout of the impingement hole and the film hole was also investigated. The study employed the RANS method with the SST k-ω turbulence model. In addition to investigating heat transfer on the impingement target wall, the heat transfer on the side wall and the impingement wall was also examined to assess heat flux distribution within the system. The results indicate that impingement distance rarely affects heat transfer on the target wall in the context of narrow double wall cooling. When the impingement distance is increased from Z/D = 1 to Z/D = 2, there is a noticeable rise in heat transfer on the side wall and the impingement wall, leading to a higher total heat flux within the impingement channel. Results indicate that reversing the positions of the impingement and film holes has negligible effect on the target wall heat transfer. Furthermore, the overall discharge coefficient, considering both the impingement hole and the film hole, remains comparable for the three schemes studied. The reverse impingement film cooling decreases the discharge coefficient of the film hole due to the large flow separation at the hole inlet.