Turbulent jet in confined counterflow

Abstract

Abstract. The mean flowfield of a turbulent jet issuing into a confined, uniform counterflow was investigated computationally. Based on dimensional analysis, the jet penetration length was shown to scale with jet-to-counterflow momentum flux ratio. This scaling and the computational results reproduce the well-known correct limit of linear growth of the jet penetration length for the unconfined case when the momentum flux ratio is small. However, for the high momentum flux ratio case corresponding to the confinement, the jet penetration length is shown to reach an asymptotic limit of about 3.57 times the confining duct diameter. This conclusion is contrary to the existing results which predict indefinite growth. A simple modification of an existing similarity solution for the jet in an unconfined counterflow provides a convenient framework for presenting the results of the flowfield and jet penetration length.

Upstream penetration behavior of the developed counter flow jet resulting from multiple jet impingement in the crossflow of cylindrical duct

“…Since x axis is co-directional with mass-averaged crossflow velocity U m as depicted in The latter demonstrates only linear dependence J 1/2 according to formula (2). The former turned out to consist of linear region  J 1/2 (or h/D) within 4<J 1/2 <30 (formula ( 2)), the non-linear region  J 1/6 (or (h/D) 1/3 ) within 30<J The obtained complicated dependence h v /D = f(J 1/2 ) looks very similar to that discovered in [8,9] when counter-flowing jet issues from centerline-located tube toward a mainstream flow of cylindrical duct (equi-density flows).…”

Characterization of the Axial Jet Separator with a CO2/Helium Mixture: Toward GC-AMS Hyphenation

“…Several works about jets in counterflow and crossflow have converged into a similar empirical mathematical expression for describing h (eq ). , K is a dimensionless empirical constant that depends on the mixing length and shear layer of the gases, Z is the ratio that relates the initial momentum of the jet with the momentum of the opposing or retarding flow, and D is the inner diameter of the confinement tubing. We suggest that Z is best represented by the ratio of the jet-to-backward momentum flows , ( J n / J p ) (eq ).…”

“…Several works about jets in counterflow and crossflow have converged into a similar empirical mathematical expression for describing h (eq 2). 32,33…”

Mixing of non-swirling and swirling inclined dense jets

“…Compared to co-and cross-flows above, studies on inclined dense jets in counter-flows are even fewer, and the reported mixing behavior is more complex with marked instabilities due to the reverse flow (Sivapragasam et al 2014). Figure 5.1(b) shows a schematic diagram of the inclined dense jet issuing into a strong counter-flow.…”

“…Compared to co-and cross-flows above, studies on inclined dense jets in counter-flows are even fewer, and the reported mixing behavior is more complex with marked instabilities due to the reverse flow (Sivapragasam et al 2014). Previous studies for non-buoyant jets in counter-flows gave substantial attention on the penetration depth (the definition of penetration depth x p is referred in Chapter 5).…”