Consideration of surface roughness during the design of internal structures for fluid transport produced by additive manufacturing of PEEK

Abstract

Additive manufacturing offers new possibilities for the design of structural components used in fluid transport. Sections of hydraulic manifolds or hydraulic blocks, parts of fluid pumps or hydraulic motors can now be manufactured with details which were not achievable with conventional manufacturing technologies, e.g., optimization of internal bends to minimize pressure drops or decrease peaks in velocity fields of fluids. However, as geometric features influence operational conditions of structural elements, pressure drop and velocity field also depend on the wall roughness of internal bends. This feature thus also has to be taken into account when designing the internal structure for the given fluid and operating conditions. In this paper, a study on surface roughness produced with additive manufacturing of polyether ether ketone (PEEK) is presented. PEEK is known for its excellent thermal and mechanical properties, resistance to wear, chemicals, and temperature which makes it an exciting material choice for structural elements with exceptional performance characteristics. First, flow of water and oil through a round pipe produced with additive manufacturing has been simulated. Two models have been used in simulations, a simplified pipe with a prescribed wall roughness and a detailed pipe with modeled surface roughness. Pressure losses and velocity fields in the pipe were then calculated. Finally, an experiment has been set to measure the pressure losses which are compared to the simulated values.