Numerical study of upward particulate pipe flows at a constant Reynolds number/Ulessuunatud ohktahkete osakeste toruvooluse numbriline uurimine Reynoldsi kriteeriumi konstantsetel vaartustel

The method based on 2D Reynolds-averaged Navier-Stokes equations has been employed for the simulation of upward turbulent particulate cylindrical pipe flows of different diameters for a constant flow Reynolds number. This approach was supplied with appropriate closure equations which took into account all pertinent forces and effects that exerted influence on gas and particles: the particle-particle, particle-wall, and particle-turbulence interactions; gravitation, viscous drag, and lift forces; and turbulence modulation. The finite volume technique was applied to the numerical solution of the governing equations. The results show the effect of the mass loading on the radial distributions of the longitudinal velocity lag, the turbulence modulation, and particle concentration. In particular, the two-way coupling of turbulence with the given particles raises simultaneously the velocity lag between gas and particles, originating from direct impact of turbulence on particle motion, and turbulence attenuation by the particles. The radial distributions of longitudinal particle velocity and mass concentration become flatter for higher flow mass loading. Key words: vertical pipe, particulate flow, terminal velocity, turbulence modulation, flow mass loading. Erineva labimooduga ulessuunatud toruvoolusi uuriti Reynoldsi meetodil keskmistatud Navieri-Stokesi telgsummeetrilistel vorranditel pohineva numbrilise meetodiga Reynoldsi kriteeriumi konstantsetel vaartustel. Seda votet kasutati koos sobivate sulgemisvorranditega, mis arvestavad koiki gaasile ja osakestele mojuvaid joude ning efekte: osake-osake, osake-sein, osakese-turbulentsi vastasmojud, gravitatsioon, viskoosne kaasahaaramine ja tostejoud. Pohivorrandite arvuliseks lahendamiseks kasutati loplike ruumalade tehnikat. Naidati osakeste kontsentratsiooni moju kiiruse mahajaamuse, turbulentsi moduleerimise ja osakeste kontsentratsiooni pikiprofiilidele. Tulemuste pohjal on vaidetud, et turbulentsi ja osakeste omavaheline vastasmoju suurendab faaside kiiruslikku mahajaamust, mis tuleneb turbulentsi otsesest mojust osakeste liikumisele ning viib turbulentsitaseme vahenemisele. Osakeste kiiruse ja kontsentratsiooni pikijaotused muutuvad osakeste suuremate kontsentratsioonide juures lamedamaks.