Heat Transfer and Pressure Drop in a Lattice Channel With Bleed Holes Available to Purchase

A lattice structure for internal cooling with coolant bleeds is investigated experimentally. The lattice configuration provides a serpentine complex flow passage where the flow takes multiple twists and turns with impingement before exiting the coolant flow channel. The combination of impingement, tortuous flow path and turbulators are expected to provide high heat transfer coefficients. In this study, measurements of heat transfer coefficient and total pressure drop were performed for a constant cross-section lattice geometry with bleed holes at the end of the passage as the flow exits. A transient liquid crystal technique was used for the measurements. Stationary tests were performed for four Reynolds number (5500<Re<22000) in a lattice structure with two inlet channels. The data indicated high heat transfer coefficients at locations corresponding to the impingement sites (with the peak Nu/Nu₀ ranging from 8–9 at the lowest Re and 3–4 at the highest Re). The spanwise-averaged Nu/Nu₀ ratios showed a rapid asymptotic development and shows constant values beyond about 10 sub-channel hydraulic diameters. Channel averaged Nu/Nu₀ values are obtained in the range 2.25–3.1. Pressure drop measurements were made, and are combined with the Nu/Nu₀ values to produce a TPF. These values are in the range of 1–1.6 with the higher values exceeding TPF’s of turbulated and pin-fin channels.