Effect of primary jet geometry on ejector performance: A cold-flow investigation

Abstract

The following cold-flow study examines the interaction of the diffracted shock wave pattern and the resulting vortex loop emitted from a shock tube of various geometries, with an ejector having a round bell-shaped inlet. The focus of the study is to examine the performance of the ejector when using different jet geometries (primary flow) to entrain secondary flow through the ejector. These include two circular nozzles with internal diameters of 15mm and 30mm, two elliptical nozzles with minor to major axis ratios of a/b = 0.4 and 0.6 with b = 30mm, a square nozzle with side lengths of 30mm, and two exotic nozzles resembling a pair of lips with axis ratios of a/b = 0.2 and 0.5 with b = 30mm. Shock tube driver pressures of P 4 = 4, 8, and 12bar were studied, with the pressure of the shock tube driven section P 1 being atmospheric. High-speed schlieren photography using the Shimadzu Hypervision camera along with detailed pressure measurements along the ejector and the impulse created by the ejector were conducted. * Hossein. Zare-Behtash@glasgow.ac.uk

Flow characteristic of highly underexpanded jets from various nozzle geometries

“…As can be seen, the flow evolution of elliptic jet at different time is similar to the circular jet. For example, the initial flow field for both jets on either ZY or XY planes is well symmetric with respect to the jet centerline and characterized by a tip vortex ring, which has been previously observed in supersonic underexpanded jets [24,25] as well as in subsonic jets [45,46]. The turbulence transitions of the circular and elliptic jets are all characterized by the breakdown of recirculation zones, the loss of flow symmetry, and the generation of streamwise vortexes, as stated in our previous study [36].…”

“…For example, Otobe et al [23] studied the influences of the nozzle geometry on the Mach disk height and diameter in highly underexpanded jets by solving the two-dimensional, axisymmetric Euler equations. Zare-Behtash et al [24,25] explored the effect of nozzle geometry on the initial shock and vortex development in supersonic underexpanded jets using high-speed schlieren photography and PIV measurements. Menon and Skews [26] reported the near-field shock structures of underexpanded sonic jets issuing from square, rectangular, elliptic, and slot nozzles based on schlieren photographs and Reynolds-averaged NavierStokes (RANS) simulations.…”

“…Zhang et al [28] investigated the initial flow differences between the supersonic underexpanded circular and square jets based on large eddy simulation. Note that most of these studies focused on the differences of near-field shock structures [23,26] or the initial flow development [24,25,28] between the jets. In the case of obtaining an indepth and comprehensive understanding on the noncircular jets, a detailed comparisons of their various flow characteristics are thus necessary.…”

Effectiveness of jet location on mixing characteristics inside a cavity in supersonic flow

“…1, where γ is the specific heat ratio, ρ is the density, M is the Mach number and subscripts 0 and jet refer to freestream and jet conditions. Schlieren photography [40][41][42][43][44] was employed to visualize the flow field around the cavity in a standard Z-type optical arrangement. A pair of 203.3 mm diameter parabolic mirrors with 1016 mm focal length and a 150W Hamamatsu Xenon continuous light source were used.…”

Transverse jet-cavity interactions with the influence of an impinging shock

“…A standard Z-type schlieren system was utilised, identical to that used by Zare-Behtash et al 25,26 The light source was a 450W continuous Xenon lamp and a Photron SA-1 highspeed camera was used to capture images at a frame rate of 10kfps with an exposure time of 1µs.…”