The compound-choking theory as an explanation of the entrainment limitation in supersonic ejectors

Olivier Lamberts, Philippe Chatelain, Nicolas Bourgeois and Yann Bartosiewicz

Energy, 2018, vol. 158, issue C, 524-536

Abstract: While the limitation of the entrainment ratio in supersonic ejectors is a well-known phenomenon, there is still a need to gain insight on the choking phenomena at play in on-design operation. In state-of-the-art simplified models of supersonic ejectors, the secondary stream is assumed to reach sonic velocity in a hypothetical throat (Fabri-choking). However, an alternative explanation of the entrainment limitation known as the compound-choking theory states that a nozzle flow with two streams at different stagnation pressures may be choked with a subsonic stream if the other one is supersonic. In this paper, the compound-choking is highlighted in a supersonic ejector through a thorough analysis of numerical simulations validated against experimental data. In addition, comprehensive experimental data of supersonic ejectors are used to assess the performance of the compound-choking theory to predict the entrainment ratio in the on-design regime in various configurations. Most predictions are in the ±10% range when compared to the experimental data. Compared to state-of-the-art 1D models relying on the Fabri-choking assumption, the compound-choking theory is shown to generally perform better regarding the prediction of the on-design entrainment ratio. This study suggests that the compound-choking theory is well suited to model the choking process in supersonic ejectors.

Keywords: Supersonic ejector; Compound-choking; Fabri-choking; CFD (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (11)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:158:y:2018:i:c:p:524-536

DOI: 10.1016/j.energy.2018.06.036

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