A Study on Characteristics of Under-Expanded Condensing Jet

Abstract

The single supersonic free jet discharging from a nozzle or an orifice has been often employed in various industrial processes. A number of studies have been done on the major features (Mach disk, barrel shock wave and the jet boundary configuration) of the supersonic jets. In the present study, numerical computations were performed to investigate the effect of initial degree of supersaturation of moist air at reservoir condition on under-expanded jet structures and the total pressure loss behind the Mach disk. From these studies, it was found that the position of Mach disk in the under-expanded moist air jets was almost the same as that in dry air jets. However, the diameter of Mach disk increased slightly with an increase in the initial degree of supersaturation of moist air. Furthermore, the total pressure loss behind the Mach disk of moist air jet changed largely in comparison to that of dry air jet.

Free underexpanded jets in a quiescent medium: A review

“…This is certainly the most studied feature in the literature, be it experimentally [12,30,35,40,43,49,51,[56][57][58][59]62,64,, theoretically [13,29,67,76,78,[95][96][97][98][99][100][101][102][103][104][105][106][107][108][109] or numerically [14,20,22,34,41,59,63,75,81,82,84,91,[110][111][112][113][114][115][...…”

“…16] or [11,Chap. 7] but the moment when this phenomenon occurs is quantitatively poorly known, especially the dependency (and interactions) on the pressure [96,29,62,30,[98][99][100]12,64,123,43,124,84,13,107,90,54]. Nonetheless, among the theoretical studies, the Mach disk location has been supposed to appear at a position such that the conservation equations are satisfied for the section perpendicular to the axis [95].…”

Influence of nozzle geometry on the near-field structure of a highly underexpanded sonic jet

“…N2 has a convergence angle b ¼ 751 at the entrance, while N3 has b ¼ 901, but the orifice exit diverges with 451 over the length 0.5D e . (Otobe et al, 2006). The shadowgraph visualization is shown in the lower half, while the present computational results are given as predicted isodensity contours in the upper half.…”

Experimental study on hysteresis phenomena of shock wave structure in an over-expanded axisymmetric jet

“…As in most of the engineering applications of supersonics jets, the working gas is usually steam or moist air and the moist air jets are qualitatively similar to dry air, but non-equilibrium condensation in moist air jet affects the shock configuration, reported by Baek et al [9] and Otobe et al [10]. Meanwhile, Kim et al [11] and Otobe et al [12] have investigated the effect of non-equilibrium condensation on the hysteresis phenomenon of under-expanded supersonic jets and reported that the moist air jet reduced the hysteretic phenomenon compared with the dry air jet, and the non-equilibrium condensation that occurs in the under-expanded moist air jet is responsible for these findings.…”