Effect of a curved turning vane on the heat transfer and fluid flow of four-pass internal cooling channels of gas turbine blades

This numerical study examined the effects of a curved turning vane on the heat transfer and pressure loss of a four-pass internal cooling channel. Three-dimensional omega-based Reynolds stress (RSM-ω) turbulence model equations were used in the computation process. Three different curved turning vane configurations were studied using a simple, without a turning vane under stationary and rotating conditions for Reynolds numbers between 20,000 and 60,000 and a rotation number of 0.042. The numerical results showed good agreement with previous experimental data. Under both stationary and rotating conditions, the curved turning vane in a hub turn reduced the pressure drop significantly compared to the conventional turning vanes. Although a curved turning vane attenuated overall heat transfer, the local heat transfer increased it in particular regions, such as the hub turn and the fourth turn of cooling passages, particularly in cases with smaller radii. Coolant flow through the hub turn of the serpentine channel can reduce recirculation, separation, and flow impingement, which are unfavorable factors of pressure loss, owing to the semi-circular configuration of the curved turning vane. Regarding the rotating conditions, four-pass channels with a smaller radius of a curved turning vane provide better overall cooling performance.