Transient Experimental and 3D-FSI Investigation of Flapper Valve Dynamics for Refrigerant Compressors

The design of the valves for refrigerant compressors has a distinct influence on the efficiency of the refrigeration cycle. In order to predict the valve behavior for compressor optimization, flow characteristics and valve system dynamics are key factors. State of the art valve model approaches have to date ignored the retainer deflection and the influence of contact effects on fluid-structure interaction behavior. With this fact in mind, experimental valve lift investigations by means of laser vibrometry measurements were performed. In order to determine the dynamic flapper valve characteristics, oscillation frequency analyses for free oscillation of the flapper valve were carried out and compared to a FEA modal analysis. Additionally this paper presents an extended three-dimensional numerical discharge valve model containing a fullycoupled fluid-structure interaction (FSI) approach. The two-way mechanical coupling is carried out by a commercial CFD code combined with a commercial FEM package. The numerical results of a 1D and the 3D-FSI model are validated using the presented experimental transient results. The numerical 3D-FSI results show good agreement with the experimental results with respect to the obtained oscillation frequencies. The 1D model allows error estimation of the mass flow considering retainer deflection. Neglecting the retainer deflection yields a maximum error of four percent for experimental boundary conditions.