Fluid dynamics in starting and terminating transients of zero-secondary flow ejector

Studies on the starting transient of a straight cylindrical supersonic exhaust diffuser: Effects of diffuser length and pre-evacuation state

“…It is mainly due to the facts that experimental methods is hardly able to resolve complex internal flows in the SED, and thus rigorous dynamics design was not amenable. Hence, the present study extends author's previous work (Park et al, 2008) on the transient fluid dynamics in the SED. With reference to previous investigation …”

“…13 shows snapshot contours of Mach number and streamlines evolving during the short diffuser starting (L/D = 2). As was visualized by Park et al (2008), gas entrainment from the vacuum chamber is most active at the early stage of the starting transient and gets gradually weakened as the diffuser flow is stabilized into its steady state. A corner eddy at the diffuser inlet appears immediately after the formation of nozzle plume and gradually vanishes as time elapses (Fig.…”

“…A high-frequency dynamic sensor located near diffuser exit (location c) records fluctuating pressures of secondary flows induced by a separation of diffuser flow and an occurrence of recirculating flow due to diffuser-exterior flow interactions. Park et al (2008) showed that an incompressible k-e turbulence scheme implemented with Sakar's turbulence compressibility model correctly depicts complex flow formation in this downstream flow regime.…”

“…A low Reynolds number k-e turbulence model (Yang and Shih, 1993) resolves strong turbulence and, as a simple remedy against the innate defect due to turbulence compressibility which is locally important in the SED downstream mixing layer, Sakar's model is incorporated (Shyy and Krishnamurty, 1997). Detailed explanations for the numerical method adopted in the study are described in our previous work (Park et al, 2008) 4.2. Solution procedure Table 2 summarizes assumptions and simplifications employed for tailoring the problem to an appropriate computational configuration.…”

Research of operation of liquid-gas ejectors with compact and dispersed jets of liquid

“…Such devices have been widely studied [1,[9][10][11][12][13][14][15] both theoretically and experimentally. However, most of the known studies of ejectors have been carried out at high liquid pressures.…”