Heat transfer enhancement of gas turbine trailing-edge cooling channel with twisted blade-like fins arranged on endwalls

• A novel low flow drag twisted blade-like fin is used in rectangular cooling channel. • The effects of twist rate and relative height on flow and heat transfer are studied. • Fin with 6.0°/mm twist rate and 0.6 H relative height has the best thermal performance. • Twisted blade-like fins induce vortex with spanwise and normalwise secondary flows. • The array of twisted blade-like fins offers great comprehensive thermal performance. A novel low-drag twisted blade-like fin is proposed in this work to enhance the comprehensive thermal performance of gas turbine trailing edge cooling channel. The influence of the twist rate and relative height of the novel fin on flow and heat transfer performance is investigated within the Reynolds number range of 14,000 to 36,000. Results show that the relative Nusselt number decreases as Reynolds number increases, ranging from 1.49 to 2.56, while the relative friction factor increases with Reynolds number, ranging from 1.16 to 12.6. The comprehensive thermal performance is improved in all cases, and is optimal at a twist rate of 6.0°/mm and a relative height of 0.6 times channel height. The flow drag increases exponentially with the increase in relative height and twist rate, while the enhancement of heat transfer performance slows down. Fins with a relative height of 0.8 times channel height can achieve over 90 % of the heat transfer performance of fins with a relative height of 1.0 times channel height, with only half the flow drag. Compared to the conventional fins, the comprehensive thermal performance of the novel twisted blade-like fin is excellent. The friction factor can be less than 30 % of that of circular pin-fin with a comparable Nusselt number, and the comprehensive thermal performance is improved by more than 55 %. The twisted blade-like fins stimulate spanwise and normalwise secondary flows, promoting fluid exchange between the walls and the channel core, thereby enhancing the heat transfer performance of the channel, in which the normalwise secondary flow plays a dominant role.