The Evolution of Flow Structures and Coolant Coverage in Double-Row Film Cooling with Upstream Forward Jets and Downstream Backward Jets

Yanqin Shangguan () and Fei Cao
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Yanqin Shangguan: College of Mechanical and Electrical Engineering, Hohai University, Nanjing 210098, China
Fei Cao: College of Mechanical and Electrical Engineering, Hohai University, Nanjing 210098, China

Energies, 2024, vol. 17, issue 14, 1-22

Abstract: The spatiotemporal evolution of the flow structures and coolant coverage of double-row film cooling with upstream forward jets and downstream backward jets, having a significant impact on film-cooling performance, is studied using the simplified thermal lattice Boltzmann method (STLBM). Moreover, the effect of the inclination angle of downstream backward jets is considered. The high-performance simulations of film cooling have been conducted by using our verified in-house solver. Results show that special flow structures, such as a sand dune-shaped protrusion, appear in double-row film cooling with upstream forward jets and downstream backward jets, which is mainly because of the blockage effect resulting from the coolant jet with backward injection. The interaction among structures results in the generation of an anti-counterrotating vortex pair (anti-CVP). The anti-CVP with the downwash motion can result in the attachment of coolant to the bottom wall, which promotes the stability and lateral coverage of coolant film. The momentum and heat transport are strengthened as the backward jet is injected into the boundary layer of the mainstream. Although the downstream evolution of the backward jet is not very smooth, its core attaches closely to the bottom wall due to the downwash motion of anti-CVP. Moreover, there is an obvious backflow zone shown in the trailing edge of the downstream backward jet with a large inclination angle. The obvious backflow makes the coolant attach to the bottom wall well. Therefore, the film cooling effectiveness is improved as the inclination angle of the downstream backward jet varies from α d o w n = 135 ° to α d o w n = 155 ° , with a constant blowing ratio of B R = 0.5 . In addition, the fluctuation of the bottom wall’s temperature is weak due to the stable coverage of the coolant layer under α d o w n = 155 ° . The film-cooling performance with an inclination angle of α d o w n = 155 ° is the best among all the cases studied in this work. This work provides essential insights into film cooling with backward coolant injection and contributes to obtaining a complete understanding of film cooling with backward coolant injection.

Keywords: spatiotemporal evolution; flow structures; coolant coverage; simplified thermal Boltzmann method; film cooling; forward and backward jets (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2024
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