Unsteady three-dimensional modeling of the Fluid–Structure Interaction in the check valves of diaphragm volumetric pumps

Abstract

A full 3D unsteady numerical model with dynamic meshes is developed to simulate the fluid–structure interaction in the non-returning valves of air-operated diaphragm volumetric pumps. This new three-dimensional CFD model provides a more accurate description of the flow patterns and a superior evaluation than a previous 2D model, published by the authors, regarding the dynamic response of the valves motion, which are responsible for internal volumetric losses that penalize the overall pump efficiency. Both piston-like and deformable geometries for the prescribed sinusoidal displacement of the membrane have been checked and compared in the modeling, resulting in similar behavior concerning the basic performance of the pump. Standard operation and free-delivery conditions are exhaustively analyzed, confirming more instabilities in the check valves in case of low air-supplied pressures. In particular, the exhausting valve is found to experience severe tapping with repetitive partial closures during the forward stroke due to an intense Fluid–Structure Interaction. On the contrary, the aspirating valve presents much better sealing characteristics with a partial reopening only at the initial moments of the backward stroke. All these numerical evidences have provided useful information for the pump manufacturers concerning the design, selection of materials and maintenance routines, which have been employed for the development of a series of new prototypes.