3D compressible simulation of a muffler with pseudosound prediction levels

Abstract

The main objective of this paper is to present a numerical resolution of a suction muffler configuration by using an in-house object oriented CFD & HT code TermoFluids (Lehmkuhl et al. 2007), able to handle tridimensional geometries, unstructured meshes and parallelization availability. This code has been adapted to be able to resolute 3D Navier-Stokes equations in their compressible form and coupled with the numerical resolution of the whole compressor domain by means of a parallel and object-oriented called NEST tool (Lopez, 2016). The numerical results aim to study the influence of the suction muffler inner geometry in the fluidynamic behavior inside the muffler while considering how this internal geometry affects the global performance of the compressor. Hence, the inlet and outlet boundary conditions at the muffler are obtained from the numerical simulation of the whole compressor using NEST, while the fluid behavior inside the muffler is numerically simulated by means of detailed analysis. In addition, the paper presents a methodology that handles with Large Eddy Simulation (LES) models for the turbulent motion of fluid inside the muffler, the formulation of Navier-Stokes in their compressible form, dealing with numerical problems derived from the compressible part, and the coupling of the whole compressor simulation to set boundary condition. Finally, the obtained results will be compared with the empirical data obtained in the CTTC facilities from the study of a real muffler placed in a reciprocating compressor.