Heat Transfer Enhancement and Thermal Performance of Lattice Structures for Internal Cooling of Airfoil Trailing Edges

Abstract

This paper presents the detailed heat transfer coefficient and pressure drop through two different lattice structures suitable for use in the trailing edge of gas turbine airfoil. The lattice structures are located in the converging trailing edge channel with the coolant flow taking a 90 deg turn before entering the lattice structure. Two lattice structures were studied with one lattice structure having four-entry channels and the second lattice structure having two entry channels. Stationary tests were performed at four Reynolds numbers (4000 < Re < 20,000) based on the inlet subchannel diameter. The results show that the two-inlet-channel lattice structure produces higher values of heat transfer coefficient and lower values of pressure drop. The data from the converging lattice structures are compared with the published pin fin data which is the common standard for trailing edge applications. It is seen that the two-inlet-channel lattice structure produces average Nu/Nu0 values in the range of 2.1–3.4 compared to a value of 1.7–2.2 for a pin fin for the current set of Reynolds number. The thermal performance factor for the four-inlet-channel lattice structure is lower than the pin fin structure but the two-inlet-channel lattice structure provides comparable or higher thermal performance compared to a pin fin structure. The lattice structures also provide additional heat transfer area and structural rigidity to the trailing edge of the airfoil. Comparable or higher thermal performance and added structural rigidity can make the lattice structure a suitable alternative of pin fins in trailing edge applications.