Analysis of the numerical modelling of turbulence in the conical reverse-flow cyclone/Duju turbulencijos ciklone modeliavimas

The paper describes the numerical modelling of the swirling fluid flow in the Stairmand cyclone (conical reverse-flow--CRF) with tangential inlet (equipment for separating solid particles from the gaseous fluid flow). A review of experimental and theoretical papers is conducted introducing three-dimensional differential equations for transfer processes. The numerical modelling of the Stairmand cyclone the height of which is 0.75 m, diameter--0.17 m, the height of a cylindrical part--0.290 m, a conical part--0,39 m and an inlet area is 0,085x0,032 m is presented. When governing three-dimensional fluid flow, transfer equations Navje-Stokes and Reynolds are solved using the finite volume method in a body-fitted co-ordinate system using standard k-[epsilon] and RNG k-[epsilon] model of turbulence. Modelling is realised for inlet velocity 4.64, 9.0 and 14.8 m/s (flow rate was 0.0112, 0.0245 and 0.0388 [m.sup.3]/s). The results obtained from the numerical tests have demonstrated that the RNG k-[epsilon] model of turbulence yields a reasonably good prediction for highly swirling flows in cyclones: the presented numerical results (tangential and radial velocity profiles) are compared with numerical and experimental data obtained by other authors. The mean relative error of [+ or -]7,5% is found. Keywords: cyclone, solid particles, numerical modelling, turbulence, one-phase flow. Nagrinejama duju aerodinamika Stairmando ciklone (kuginis griztamojo srauto (KGS) ciklonas--irenginys kietosioms dalelems atskirti is oro srauto) spendziant tangentinio srauto itekejimo skaitinio modeliavimo problema. Apzvelgti eksperimentiniai ir teoriniai darbai ciklonuose, kuriuose susidaro ypac sudetingas sukurinis srautas. Pateiktos trimates pernasos diferencialines lygtys nespudziajam turbulentiniam srautui ciklono viduje, kurios skaitiskai issprestos baigtiniu turiu metodu taikant standartini k-[epsilon] ir RNG k-[epsilon] turbulencijos modelius. Atliktas skaitinis oro srauto judejimo modeliavimas Stairmando ciklone, kurio aukstis yra 0,75 m, skersmuo--0,17 m, cilindrines dalies aukstis--0,29 m, kugines--0,39 m, itekejimo angos plotas--0,085 x 0,032 [m.sup.2]. Oro srauto judejimo ciklone matematini modeli sudaro Navje ir Stokso (Reinoldso) trimaciu diferencialiniu lygciu sistema. Modeliavimo rezultatai--tangentinio ir asinio greicio profiliai ciklone taikant RNG k-[epsilon] turbulencijos modeli, kai itekejimo greitis 4,64 ir 14,8 m/s, o debitas--atitinkamai 0,0112 ir 0,0388 [m.sup.3