Heat Transfer and Pressure Drop in a Converging Lattice Structure for Airfoil Trailing Edge Cooling

Lattice-matrix structures have distinct advantages in enhancing heat transfer in the cooling channels of a gas turbine blade. Lattice structures not only enhance heat transfer coefficient but also provide structural rigidity to the turbine blade. Stationary tests were performed for a 12 times scaled up model at four Reynolds numbers (4,000 < Re < 20,000) in a converging lattice structure. A narrow band liquid crystal technique is used to determine the heat transfer coefficient in the channel. The results shows very high heat transfer coefficient enhancement in the impingement regions. The average heat transfer coefficient enhancement for a channel with lattice structures is also higher (Nu/Nu₀ = 1.9–3) than a pin fin cooling configuration channel (Nu/Nu₀ = 1.7–2.2). The heat transfer coefficient enhancement decreases with increasing Reynolds number. Pressure data are taken at some specific points throughout the channel. High pressure drop due to the turning of the flow in the lattice structure is observed. Friction factor and overall thermal performance factor are calculated. The overall thermal performance factor lies in the range 0.64–1.