Heat transfer characteristic of the asymmetrical impingement cooling on the guide shield

This paper investigates the experimental and computational examination of the impingement-film compound cooling structure on the asymmetric leading edge (LE) of the guide shield. The experiments involve varying the diameters of impingement holes (D₁ and D₂) and analyzing how Reynolds number (Re) and impingement distances (H/D₁, H/D₂) affect heat transfer using transient liquid crystal (TLC) measurement technology. Additionally, numerical simulations are utilized to study the flow dynamics and heat transfer mechanisms in impingement cooling. The findings reveal that heat transfer uniformity is notably enhanced when using a diameter of D₁ = 8.5 mm. The convergence of two impingement jets results in the generation of a fountain flow, creating secondary vortices near the wall that induce secondary impingement, thereby enhancing heat transfer. This phenomenon becomes more pronounced at higher Res and smaller impingement distances. As the Re increases, impingement velocity rises, consequently boosting heat transfer. The suction effect of the film holes strengthens, resulting in a more significant difference in heat transfer between the suction surface (SS) and pressure surface (PS). Decreasing the impingement distance enhances the velocity of the jet reaching the target surface, thereby substantially improving heat transfer. Within the scope of this study, the optimal structure is D₂ = 12 mm and H/D₂ = 2.6, which increases the area-averaged Nu (Nu_ave) by 35.7 % and 73.5 % compared to H/D₂ of 3.6 and 5 at all Re conditions, respectively. An empirical correlation formula for the Nu_ave is summarized, providing effective guidance for implementing the impingement-film compound cooling structure on the guide shield.