Distribution characteristics of the mass concentration of coarse solid particles in a two-phase turbulent jet

Influence of Stokes number on the velocity and concentration distributions in particle-laden jets

“…Figure 10 also shows that the Sk 0 = 11.2 case exhibits a longer "potential core", and a lower rate of centreline decay than the lower Stokes number cases, consistent with previous observations (Prevost et al 1996). However, the centreline decay rate of the particle velocity scales more closely with x (with a negative gradient) than with x −1 over this measurement range, consistent with measurements at similar high Stokes numbers by Hardalupas et al 1989 (Sk 0 = 10, φ = 0.8) and Frishman et al 1999 (Sk 0 = 21, φ = 0.62), which are also shown in the figures. The most likely explanation for the departure of the centreline velocity decay from the expected x −1 profile can be found from the axial evolution of the local Stokes number, defined as…”

“…Therefore, an understanding of particleladen flows is crucial to optimising combustion processes in industrial systems to enable the design of safer, more energy efficient combustion systems with lower emissions. The significance of these flows has resulted in considerable effort to understand them over the years, with the result that much is now known about particle-laden turbulent jets (Gillandt et al 2001;Hardalupas et al 1989;Modarress et al 1984a;Prevost et al 1996;Sheen et al 1994;Shuen et al 1985;Fan et al 1997;Fleckhaus et al 1987;Frishman et al 1999;Mostafa et al 1989;Tsuji et al 1988). However, the greater complexity of these flows over their single-phase counterpart, which includes the introduction of many additional parameters together with the many additional experimental challenges introduced both by the conveying fluid and the measurement of particle-laden flows, means that many gaps in understanding persist.…”

“…Of the previous measurements of the velocity field (Gillandt et al 2001;Hardalupas et al 1989;Modarress et al 1984a;Prevost et al 1996;Sheen et al 1994;Shuen et al 1985;Fan et al 1997;Fleckhaus et al 1987;Frishman et al 1999;Mostafa et al 1989;Tsuji et al 1988), only five (Fan et al 1997;Fleckhaus et al 1987;Frishman et al 1999;Mostafa et al 1989;Tsuji et al 1988) also report the concentration of the dispersed phase. Of these, none report the important Stokes number (Sk 0 ) range of order unity, in which the particle response time is the same order of magnitude as the fluid time scale, but are instead limited to the range of Sk 0 > 9, in which particles exhibit a relatively weak response to turbulent motions.…”

Experimental data for solid–liquid flows at intermediate and high Stokes numbers

“…The cross-talk can be produced by the trajectory ambiguity, the intrinsic distributions in size from the dispersed phase (not perfectly monodisperse) and the depth of field (Hardalupas et al 1989;Albrecht et al 2003). To avoid the interferences, some studies have used simultaneous channels tuned independently for each of the phases (Frishman et al 1999) or incorporate measurements of the Doppler amplitude (Tsuji & Morikawa 1982). Some other studies combine different techniques as in Lau along with planar nephelometry (PN).…”

Numerical Simulation of Uprising Turbulent Flow by 2d Rans for Fluidized-Bed Conditions

“…This implies that the diffusive source terms were retained only in one direction, namely in the transverse one, and the magnitude of the average transverse velocity components of the gas-and dispersed phases was much less than that of the longitudinal components of the corresponding velocities of gaseous and dispersed phases. Such approach is thoroughly valid and used in the case of pipe channel flows as well as in the turbulent round jets [3][4][5].…”