Compressible Flow Analysis of Thrust Augmenting Ejectors

The present work was initiated due to the need for a method to understand and predict the thrust augmenting characteristics of jet ejectors. The mixing process in ejectors can be analyzed using either the control volume approach, or detailed models based on the Navier -Stokes Equations and the theory of turbulent jets. The control volume approach uses integrated forms of the conservation equations of mass, momentum and energy. It is chosen in the first part of the study since it affords the best vehicle for the parametric studies required to understand the potential of ejectors for a given application. Compressibility effects are taken into consideration. Losses, however, are not accounted for in the analysis. A more detailed approach, based on the turbulent mixing model derived by Abramovich, is presented in the second half of the study. The model used proved to be very accurate in describing the turbulent mixing flow process taking place in the ejector chamber. The results from the two approaches are found to be in good agreement, although some discrepancies could be found in the case of supersonic ejectors