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John Hind

    Hi Chris – CFD has been used for pulsing flows – see this paper from 2009.

    Numerical simulation of transient flows
    in a vacuum ejector-diffuser system
    V Lijo1,HDKim1∗,G Rajesh2, and T Setoguchi3
    1School ofMechanical Engineering, Andong National University, Andong, Republic of Korea
    2Indian Institute of Space Science and Technology, Kerala, India
    3Saga University, Saga, Japan

    Abstract: The objective of the present study is to analyse the transient flow through the vacuum
    ejector system with the help of a computational fluid dynamics method. An attempt is made
    to investigate the interesting and conflicting phenomenon of the continuous entrainment into
    the primary stream with limited mass supply from the secondary chamber. The results obtained
    show that the one and only condition in which a continuous mass entrainment can be possible
    in such types of ejectors is the generation of a recirculation zone near the primary nozzle exit. The
    flow in the secondary chamber attains a state of dynamic equilibrium of pressure at the onset of
    the recirculation zone. A steady flow assumption in such ejector systems is valid only after the
    dynamic equilibrium state.
    Keywords: compressible flow, ejector, internal

    Proc. IMechE Vol. 224 Part G: J. Aerospace Engineering