Effect of Triangular Grooved Tip on Blade Tip Region Heat Transfer

초록

A numerical analysis was conducted to investigate the effect of the triangular grooved tip shape on the flow and heat transfer characteristics near the tip region. To study the effect of the triangular grooved tip shape, five triangular grooved tips were designed by changing the relative apex location of the triangular groove. Numerical computations were conducted for a total of six tip shapes, including a squealer tip. The contour plot of the secondary velocity and streamline were analyzed to understand the flow over a blade tip in detail, and the effect of the leakage vortex was discussed by comparing the total pressure loss. To compare the heat transfer characteristics, the Nusselt number and heat load over the tip surface, including the cavity sidewall, were analyzed. Results showed that the origin and trace of the vortex in the tip cavity depended on the apex location of the triangular groove, and because of this, the Nusselt number on the tip and blade suction side surface were also affected. Among the considered tips, the triangular grooved suction side tip showed comparable flow loss to that of the squealer tip. It also showed a lower heat transfer than the other tip shapes.

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