Conference Year
2016
Keywords
reciprocating compressors, reed valves, computational fluid dynamics, cut-cell method, automatic meshing
Abstract
Computational Fluid Dynamics (CFD) models can offer great insight into flow phenomena and complex fluid-structure interactions present in reciprocating compressors. This is often achieved, however, at large computational cost and considerable user setup time. In this study, a Cartesian cut-cell finite-volume method is applied to model a small displacement refrigeration compressor. The cut-cell method has the key feature of representing discrete cell volumes exactly without requiring the computational grid to coincide with the bounding geometry. Additionally, the grid is dynamically generated at each time step based on the instantaneous boundary positions and is automatically refined based on gradients of local flow variables. These two features make this method ideal for modeling the deformation of the valves, the motion of the piston, and the complex geometries of the suction and discharge mufflers. The model is validated against experimental data. The sources of numerical error in the model are assessed, including the spatial and temporal discretization error and the model treatment for valve opening, closure, and contact. Lastly, several automated grid generation strategies are presented to establish guidelines for balancing cost and accuracy. The model formulation highlights the ease of incorporating complex and moving geometries characteristic of reciprocating compressors into a CFD model at a reasonable cost.