Session: 13-05: Influence of manufacturing techniques on heat transfer

Paper Number: 153016

Systematic Numerical Investigation on the Surface Roughness Effects on the Friction and Heat Transfer of Additively Manufactured Components 

The gas turbine community is exploring with growing interest the applicability of additive manufacturing (AM) for cooling applications, considering the possibility to consolidate multiple parts and increase the complexity and performance of the cooling system without impacting on costs and lead time.

However, design must take into account unwanted aspects associated with the AM process, such as geometric deviations and increased surface roughness, which occur particarly in case of small features, high scan speed and very inclined build orientation. This can increase significantly the pressure drop and more marginally heat transfer.

In the last ten years, an increasing number of papers focused on performing experimental tests to characterize the aerothermal performance of different cooling features like straight and wavy channels, pin fins, ribs and more recently lattice and triply periodic minimal surface (TPMS) structures like gyroids. Less attention is devoted to the numerical simulations accounting for such roughness effects, which is typically neglected by considering the walls as smooth.

This paper aims at performing CFD simulations of several experimental test cases, modelling the walls as both smooth and rough. By investigating different test cases with different dimensions, the work aims at i) carrying on the validation and calibration of the roughness models with experimental data and ii) understanding when roughness starts playing a significant role.

By doing that, it will be possible to point out when roughness is relevant, when appropriate correction models are required in CFD and a way to estimate approximately the values for the calibration parameters. From a design perspective, the work will also contribute to highlighting when the dimensions of the features and channels are big enough to neglect conservatively roughness effects.

Presenting Author: Lorenzo Mazzei Ergon Research

Presenting Author Biography: Lorenzo Mazzei is a CFD Engineer and R&D Programs Manager at Ergon Research, where he provides CFD-based solutions for the development of innovative products. He works in the sectors of aviation, power-gen, oil&gas, automotive and renewables, improving the design in fluid, heat transfer, combustion and thermal management applications.

Authors:

Niccolò Casini Ergon Research
Sergio Machado Ergon Research
Lorenzo Mazzei Ergon Research
Riccardo Da Soghe Ergon Research