DESIGN ANALYSIS OF CENTRAL AND ANNULAR-JET EJECTORS,

Abstract : An extension of the principles of ejector operation is presented in an analysis which will aid the engineer in designing central- and annular-jet ejectors. Particular attention is focused upon applying the governing conservation equations of mass, momentum and energy to the problem of handling the various regimes of ejector operation. A modified impulse function was deduced which unifies the zero secondary flow and non-zero secondary flow ejector analysis. Application of this function to determine the effects of various influences on ejector performance such as: (a) Mach number regimes of the primary and secondary streams, (b) unequal stream stagnation temperatures, (c) wall friction, (d) the effect of unequal static pressure, was made and results presented. The analysis was applied to estimate the performance characteristics of both central- and annular-jet ejectors and is compared with experimental data in many instances. Systematic ejector operating curves are introduced, and a design analysis is developed therefrom which is rapid and straightforward. It is believed that the analysis and design procedures as applied to annular ejectors is unique. Finally, the performance characteristics of central- and annular-jet ejectors are compared to indicate the suitability of each for given pumping requirements. (Author)