Distributed Element Roughness Model for Cooling Channels

This technical report presents a discrete element roughness model (DERM) applied to additively manufactured internal cooling channels, specifically in the context of turbine blades. It discusses the challenges associated with accurately predicting drag and heat transfer in these channels due to the large-scale roughness created by additive manufacturing techniques. DERM offers a solution by leveraging volumetric roughness modeling, which significantly reduces computational costs compared to traditional methods. The paper outlines the model's unique features, such as a generalized treatment of drag and a two-layer model for Reynolds stresses. Various rough surface configurations are examined, with flow characteristics analyzed against results from previously reported direct numerical simulations. The findings demonstrate that the DERM can effectively handle random roughness typical of additive manufacturing, offering a more flexible approach for engineers seeking to optimize turbine blade cooling designs. The report concludes by suggesting potential improvements for the model and highlights its applicability across diverse roughness fields.