CFD simulation as a tool for the identification of the manifold element reaction to pressure pulsations excitation (one- and two-phase flow)

The periodicity of compressor operation is a source of pressure pulsations in volumetric compressor manifolds. An analysis of pressure pulsations is important for several reasons. The Helmholtz model, applied in all commercial programs offered by the companies professionally dealing with damping pressure pulsations, contains numerous simplifying assumptions; a straight pipe segment, with an ideal gas isentropic flow assumption, substitutes each element of the piping system. In many cases this model is insufficient. The existing experimental methods could not be used in the design of a muffler. The aim of this paper is to show a new method to identify an arbitrary fragment of a manifold, i.e. a method of identification of the appropriate complex transmittance matrix elements using CFD simulation. This method allows the liquid phase dispersed in the compressed gas and non ideal gas as a working medium to also be considered. The most important conclusion of this work is that identification of acoustic element parameters in the manifold, based on multi-dimensional simulation model, is feasible. The author obtained much better results from the developed method than those yielded by the classic Helmholtz model. A comparison between pure gas and gas with oil contamination is also shown in the paper