Optimisation of Reed Valves Dynamics by Means of Fluid Structure Interaction Modelling

In this study the dynamic of a six petals reed valves pack is simulated accounting the complex fluid interaction phenomena occurring during transient flow of a typical working cycle of a two-stroke engines for go-kart competition. Starting from previous works on FSI (Fluid Structure Interaction) simulation for 2D cases and after the optimization of valve material considering only the structural 3D dynamic, this new step has been carried out thanks to a further development of a dedicated approach. Technically speaking, the proposed methodology consists in the use of FLUENT coupled with an embedded FSI tool based on a suite of UDF (User Defined Functions). This tool allows to generate a FEM structural model consistent with fluid mesh boundaries, to exchange information between FEM and CFD model (pressure and displacements through a weak approach on a time step basis or within the non-linear iteration), to solve the structural part adopting a general shell element type, and to account for contact non linearity. The coupled case definition is fully integrated in FLUENT by means of an user-friendly GUI and a TUI written in scheme language. The analysis of reed valve opening under steady boundary condition, considering the transient of fluid during valve opening, is presented.