A one dimensional model for the determination of an ejector entrainment ratio

The proposed model is a new approach for the evaluation of the entrainment ratio of double choked ejectors, based on a perturbation procedure of linearized and axisymmetric supersonic flow. The model is developed in three regions: (i) the primary flow nozzle, (ii) the secondary flow channel, and (iii) the region of interaction between the supersonic nozzle jet and the secondary flow. Primary and secondary flows are assumed isentropic. A simultaneous numerical solution of the governing equations of the three regions is obtained by dividing the external supersonic jet flow in small volumes, where the external pressure, corresponding to the secondary flow pressure, is assumed constant in each volume. The model has been evaluated against experimental results obtained elsewhere, especially data from the Huang et al. (1999) investigation. The absolute average deviation of model entrainment ratio with respect to experimental data is of the order of 7%.