Movable and Adjustable Injection of Air through Concentrated Sources of Mass and Momentum for the Pneumatic Atomization of Polyurethane and the Modeling of Droplet–Fiber–Interaction for the Manufacturing Process of Polyurethane–Fiber–Reinforced Composites

Abstract

For the manufacturing process of polyurethane-fiber-reinforced composites the liquid plastic polyurethane (PUR) is sprayed on a substrate. Simultaneously fibers are injected in the spray cone for wetting before the entire composite deposits and starts curing. The quantification of the influence of some process parameters like the air mass flow, the droplet size and distribution or the fiber injection angle on the fiber orientation and distribution on the substrate are to be analyzed. The modeling of the spray is carried out using a RANS Euler-Lagrange approach coupling the droplets with the gas phase in a four-way coupled manner. Thereby a new approach is presented for the moving air injection, where mass and momentum source terms are applied to a new set of adjacent cells according to the predefined motion of the injector. The fiber-droplet-coupling is realized either by artificially mixing the droplets and the air to a fictive fluid through a process called “homogenization” or by considering the dense droplet flow as an Eulerian phase through a process called “semi-homogenization”. The influences of both approaches are to be compared regarding the fiber distribution and orientation on a substrate.