scroll compressor modeling, discharge muffler system, pressure pulsation, reed valve dynamics, computational fluid dynamics
The recent requirements on the scroll compressors used in air conditioning systems are focused on the reduction of the noise and the improvement of the efficiency. To achieve this, the complex fluid flow phenomenon taking place inside of the compressor must be better understood. Two modeling approaches for investigating this problem are one-dimensional multi-physics modeling and three-dimensional computational fluid dynamics (CFD) modeling. The one-dimensional multi-physics based models are available to perform these calculations with low computational cost, but the influence of detailed geometrical effects on the fluid flow behavior is not taken into account. This paper deals with the development and application of a three-dimensional CFD model for a scroll compressor. To deal with the challenge of the complicated moving geometries of the orbiting scroll and the deforming reed valves, an automated meshing strategy is employed to dynamically calculate the working chamber volumes based on the instantaneous geometry positions. Thereby no user meshing is required, and the resulting Cartesian cut-cell based mesh has the desirable numerical properties of orthogonality and low numerical diffusion. The motion of the discharge reed valve is determined using a fluid-structure-interaction model considering the valve as a one-dimensional deforming cantilever beam and considering the valve geometry and variable cross sections. The comparisons between the simulation and experimental results, e.g. indicator diagram, discharge valve motion and deformation, and pressure pulsation indicate that a good correlation is achieved, while the computational time stays acceptably low. The spatial and temporal convergence of the numerical method is demonstrated, particularly for the computation of the internal pressure and discharge pressure pulsation. The results show that the developed simulation model can be used to improve and to optimize the compressor design process by reducing the demand on prototype testing and to improve the understanding of the internal flow in the system.