Session: 13-02 - Additive Manufacturing

Paper Number: 126159

126159 - Assessment of Additive Manufactured Micro-Channel Characteristics: Impact of Hydraulic Diameter Evaluation 

Among internal cooling techniques for gas turbines components, skin cooling is recognized as one of the most promising, especially thanks to the spread of additive manufacturing techniques. In this regard, several studies have tried to characterize heat transfer and pressure loss performance of additive manufactured micro-channels, as well as the impact of AM characteristic parameters, mainly in the form of building angle, and resulting surface roughness and channel shape. The open literature offers several correlations in terms of friction and HTC coefficient using a representative hydraulic diameter. Despite that, little attention is given on the importance of such characteristics length definition which may lead to under/over estimation of the cooling rates when correlations are used in the design

In this work, coupons featuring circular micro-channels with diameters of 0.5 and 1 mm and different building angles have been tested, to retrieve pressure losses and an average heat transfer coefficient through a lumped approach. The coupons were additive manufactured using the Laser Powder Bed Fusion (L-PBF) technique. Exploiting the experimental survey, the impact of the considered hydraulic diameter was investigated, by comparing different approaches based through a direct measurement. An additional and new approach, aimed at the identification of an “effective” diameter, based on fluid-dynamic considerations, was also considered.

The data correlation and the comparison with available correlations from different authors showed that newly proposed approach to provide superior scaling capabilities and, in turn, allowing for the development of more accurate prediction methods.

Presenting Author: Tommaso Bacci University of Florence

Presenting Author Biography: Tommaso Bacci is a PhD Researcher of the Department of Industrial Engineering of University of Florence where he got his PhD in 2018. His studies mainly deal with heat transfer and aerodynamics in gas turbines, with particular focus on the topic of combustor-turbine interaction and turbine cooling.

Authors:

Tommaso Bacci University of Florence
Alessio Picchi University of Florence
Niccolò Castelli University of Florence
Bruno Facchini University of Florence
Francesco Morante Baker Hughes
Luca Innocenti Baker Hughes