An experimental investigation on pressure loss and local heat transfer characteristics in additively manufactured ribbed cooling configurations

Abstract

Pressure loss and transient heat transfer measurements are performed on real-scale turbine cooling configurations at engine-relevant flow conditions. To determine the influence of rib turbulators and surface roughness on heat transfer and pressure loss, five additively manufactured models and one milled model were investigated, which distinguish in their manufacturing-related surface roughness and/or rib turbulator configurations. The experimentally determined friction factors are compared with data from a computed tomography (CT) scan, which was carried out for one of the additively manufactured models. An inverse discrete volume approach is applied, where the temperature response of the accessible outer wall caused by a sudden change in the temperature of the fluid flowing through the channel is measured. This allows the determination of locally resolved heat transfer coefficients on the non-accessible inner surface and provides information about the internal heat transfer processes. From the variety of experiments performed on the six models, the influence of surface roughness, one-sided high-blockade ribs, combination of these two, and the Reynolds number on friction factor and heat transfer coefficient is determined. The effects of roughness and rib configuration are separated from each other, and the expected measurement uncertainties are estimated by means of a sensitivity analysis.