Improving internal cooling performance of turbine blade with steam in channel with rhombus-patterned biomimetic ribs: A numerical investigation

Gas turbine blades can achieve better internal cooling performance with steam than air. A biomimetic structure based on sharkskin scales has demonstrated that the designed rhombus-patterned ribs can significantly improve the internal cooling performance with air. In this work, a channel with 60 degrees parallel ribs and two channels with rhombus-patterned ribs having different height arrangements (constant height and decreasing height) is established. The effect of Reynolds numbers on the flow and heat transfer is investigated. The results show that steam increases the averaged Nu by 16.59%-25.69% as compared to air. The constant height rhombus-patterned ribs cooled by steam show the best cooling performance, with also the highest flow resistance. The decreasing height rhombus-patterned ribbed channel with steam cooling has the best overall thermal performance, due to the weakened vortex intensity by decreasing rib height and the alleviation of poor heat transfer behind the ribs caused by the Coanda effect. Thus, steam cooling of the rhombus-patterned ribbed surface is proved to be capable of achieving excellent cooling performance. This work helps develop novel internal cooling structures inspired by bionic surfaces with the aim of heat transfer enhancement and drag reduction.