Abstract
The objective of the present study is to investigate the transient flow through the ejector system. An attempt is made to investigate the interesting and conflicting phenomenon of the infinite entrainment of secondary stream into the primary stream from a finite secondary chamber. The present study is also intended to identify the operating range of vacuum ejector-diffuser systems where the steady flow assumption can be applied without uncertainty, with the help of a computational fluid dynamics method. The results obtained show that the one and only condition in which an infinite mass entrainment is possible in such types of ejectors is the generation of a re-circulation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium of pressures at this point. A steady flow assumption is valid only after this point.
