Overall cooling effectiveness and flow characteristics of multi-row effusion cooling with forward and backward injection: Effects of inclination angle, blowing ratio, and a combined slot-effusion scheme
International Journal of Thermal Sciences, cilt.230, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 230
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.ijthermalsci.2026.111184
- Dergi Adı: International Journal of Thermal Sciences
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Backward injection, Conjugate heat transfer, Effusion cooling, Gas turbine
- Orta Doğu Teknik Üniversitesi Adresli: Evet
Özet
The backward coolant injection concept, in which the coolant is introduced into the mainstream in the reverse direction, has been proposed as a strategy to enhance the thermal protection of gas turbine hot-section components. The primary objective of this study is to establish a physical understanding for backward injection by characterizing its sensitivity to key parameters. Steady Reynolds-averaged Navier–Stokes (RANS)-based conjugate heat transfer (CHT) simulations were performed on a multi-row effusion-cooled flat plate to evaluate the effects of inclination angle (20°-60°) and blowing ratio (BR = 0.5-1.5). In addition, the influence of thermal conductivity (0.4-6.25 W/m·K) on overall cooling effectiveness was investigated. The results show that the inclination angle strongly governs vortex structures and overall cooling effectiveness. At low coolant supply, 20° forward holes provided the highest effectiveness, whereas backward injection at the corresponding angle (160°) did not improve performance and exhibited rapid downstream decay of kidney vortices. In contrast, the 60° configuration preserved vortex structures for both injection directions, allowing backward holes to outperform forward holes at BR = 0.5. For backward injection, vorticity magnitude and turbulent kinetic energy (k) increased with blowing ratio. The effect of thermal conductivity was found to depend on the mainstream heat transfer coefficient (HTC) level. Additionally, the combined slot-effusion scheme (slot BR = 0.2; effusion BR = 0.3-0.5) significantly enhanced cooling effectiveness for both configurations, particularly in the upstream region where effectiveness approached unity.