CFD analysis of a supersonic air ejector. Part II: Relation between global operation and local flow features

This paper presents an original CFD analysis of the operation of a supersonic ejector. This study is based on CFD and experimental results obtained in the first part paper [A. Hemidi, F. Henry, S. Leclaire, J. M. Seynhaeve, Y. Bartosiewicz, Experimental and numerical analysis of the operation curve of a supersonic ejector, single-phase and two-phase operation, Submitted to Applied Thermal Engineering]. Results clearly demonstrates that a good predictions of the entrainment rate, even over a wide range of operating conditions, do not necessarily mean a good prediction of the local flow features. This issue is shown through the results obtained for two turbulence models, and also raises the problem of their assessment. In addition, an analysis based on the sonic line location in order to locate the choking cross-section is proposed in this paper. Based on this approach, this parameter allowed to propose an explanation of such disparities between good predictions of overall performances and significant discrepancies of local flow parameters.