Flow phenomena in stirred tanks. Part II. The bulk of the tank

Abstract

O r a d p r e sFig. A2. Velocities and angles used for calculating of the energy flux through control surface 1. tropic at any z in the impeller stream at s = 7 cm: Incorporating these simplifications and neglecting fluctuating velocities raised to the power 3, we get 11 = nrlp j'Ila [ ( ~sres + ~v r e s u2r,~) COST -2 T J r e s K s s i n 7 dz (A16)The flux of kinetic energy through control surface 2 was determined similarly by assuming that uraa was negligible and that the flow was isotropic: r e s , a t + m r e s , a t y z r e s , a t ) c0s-C-2f7res,at&es,at sin 71 rdr (A17) CTres,,t is the sum of the velocity components v,, and ntan, and ure7,,,t is the fluctuating velocity in direction of Ures,at. The -/ Fig. A3. Velocities and angles used for calculating the energy flux through control surface 2.angles and velocity components are shown in Figure A3. All the terms in Equations (AlG) and (A17) were obtained from measured velocities. The control surfaces were set at s = 7 cin and z2 = t 3.75 cm for the data presented in Tahle 2 . Part II. T h e Bulk of the TankTurbulence parameters were measured in the bulk of turbulent stirred tanks of 45.7 and 91.4 cm diameter with air as the working fluid. Three types of turbine impellers were studied ranging in diameter from 22.8 to 45.7 cm. The turbulence in the bulk of the tank was essentially homogeneous and isotropic. The normalized one-dimensional energy spectra and the Eulerian autocorrelation functions were approximately the same throughout the tank and for all tanks, impellers, and operating conditions. The space averaged turbulent velocities were correlated by using the turbulent energy equation. A transformation of the measured spectra from the frequency space to the wave number space was accomplished. Integration of the dissipation spectra in the wave number space confirmed that most of the energy input is dissipated in the bulk of the tank through the turbulent motion. The results were extended to low viscosity liquid systems and used to interpret the data on mass transfer from suspended particles.

Experimental study of the influence of the rows of vortex generators on turbulence structure in a tube

“…For this reason, several hydrodynamic studies of mixer-reactors over the last 20 years have focused on predicting or measuring the distribution of this parameter. However, since mechanical stirring is still widely used in the chemical processing industry, almost all hydrodynamic studies performed to date on mixer-reactors have been based on this type of device (Cutter [2], Sato et al [3,4], Mujumdar et al [5], Rao & Brodkey [6], Komasawa et al [7], Gunkel & Weber [8],…”

“…Komasawa et al [7], Gunkel & Weber [8], Barthole et al [10], Wu & Patterson [12], Baudou et al [13] as well as Mavros et al [14]).…”