Investigations of flow and heat transfer characteristics in wedge-shaped channels embedded with lattice structures

Truss-type lattice structures exhibit great application potential for turbine blade cooling. However, current research on lattice structures is limited to rectangular cooling channels, leaving their heat transfer characteristics in the wedge-shaped channels of turbine blades unclear. This study employed transient liquid crystals (TLC) technique and numerical simulations to investigate the flow and heat transfer characteristics of Kagome and Body Centered Cubic (BCC) lattice structures within a wedge-shaped channel, representing the trailing edge of a turbine blade. Results from a traditional pin-fin channel were used as a comparison benchmark. The findings indicate that the decrease in the height of the wedge-shaped channels along the flow direction leads to mainstream acceleration, resulting in a continuous enhancement of heat transfer on the channel walls. Unlike rectangular channels, the pressure loss caused by the lattice structures in the wedge-shaped channels is comparable to that of the pin fins, thereby improving the overall thermal efficiency. Additionally, the unique topology of the Kagome lattice structure causes low-momentum vortex pairs behind its central intersection to continuously rise in the wedge-shaped channel, ultimately washing over the top endwall and resulting in a linear increase in the heat transfer level. Overall, this study reveals that replacing pin fins with lattice structures at the turbine trailing edge can enhance the cooling performance without significantly impacting the pumping power.