A SEMI-EMPIRICAL ONE-DIMENSIONAL MODEL FOR FLOW IN EJECTORS USED FOR GAS EVACUATION

摘要

Ejectors are considered an integral part of numerous engineering applications such as chemical processes, desalination, and refrigeration. The majority of past research in this field was aimed at developing simplified one-dimensional models for the ejector flow problem. The main advantage of those models is that results can be obtained almost instantly as opposed to experimental or CFD work and they are also flexible in that they allow the user to change various operating and geometric parameters. Despite the success of some of those models, they are inherently unable to incorporate common multi-dimensional phenomena such as oblique shocks and shock-induced boundary layer separation.rnThis work relies on experimental and CFD results obtained earlier by the author for a certain ejector geometry to develop a semi-empirical one-dimensional model where empirical formulation is used wherever multi-dimensional effects need to be taken into account. One of the features of this model is that it can be used at both design and off-design conditions but is currently limited to low exit pressure conditions, making it suitable for modeling ejectors used in applications such as gas evacuation where exit pressure is nearly ambient.rnThe paper presents the results of the semi-empirical one-dimensional model for three geometries. The validity of the results is tested by comparing it with reliable numerical data.