Laser Doppler Anemometer Measurements in Bubble Column:  Effect of Sparger

Abstract

Measurements of flow pattern in a 150 mm i.d. bubble column were carried out using a laser doppler anemometer (LDA) in a forward scatter mode. A superficial gas velocity of 20 mm/s was used in all the experiments. Two different spargers (perforated plate and porous plate) were employed. The liquid flow starts developing from the sparger where non-uniformities in the gas sparging exist. From z/D ≥ 2 (z = axial location; D = column diameter), the fully developed axial liquid velocity profiles are seen. The radial variation of mean axial velocity shows gross liquid circulation in the column. Circulation velocities are smaller for the bubble column with porous plate sparger mainly due to the fact that the mean bubble size is small and the gas distribution is relatively uniform over the column cross-section. The difference in the hydrodynamic behavior with two different spargers is also apparent from the profiles of the turbulent kinetic energy and Reynolds stress measured from the velocity−time series.

CFD simulation of bubble column—An analysis of interphase forces and turbulence models

“…The performance of three CFD models, viz k-ε, RSM and LES, has been compared with the experimental data of Bhole et al [2]. Near the sparger, none of the turbulence model has been able to predict the axial velocity profiles and the gas holdup profiles as reported experimentally.…”

“…These models are applied to simulate the hydrodynamics (global as well as local) of a cylindrical bubble column arising due to the use of three different spargers (a sieve plate sparger, a single hole and a sintered plate sparger) at the superficial gas velocity of 20 mm/s. The predictions of axial velocity, gas hold-up, turbulent kinetic energy and Reynolds stress profiles have been compared with the experimental data of Bhole et al [2] and kulkarni et al [3]. The bracketed numbers indicate the experimental values.…”

“…The CFD study of sensitivity of different interphase forces, like drag, lift and added mass have been performed for the experimental data of Menzel et al [1], which is an industrially relevant cylindrical column. The understanding was then extended to study the performance of different turbulence closures in simulating the flow development arising out of three different spargers namely a perforated plate (multipoint sparger), a single hole and a porous plate in an laboratory scale bubble column [2,3]. The relative merits of the various force formulations and the turbulence models have been brought out and finally, some recommendations have been made for appropriate selection.…”

Quantifying sub-grid scale (SGS) turbulent dispersion force and its effect using one-equation SGS large eddy simulation (LES) model in a gas–liquid and a liquid–liquid system

“…Bubble column: The experimental details and dataset for validating the bubble column simulation was obtained using laser Doppler velocimetry (LDV) by Bhole et al (2006) and Kulkarni et al (2007). This dataset was used previously by Tabib et al (2008) for validation of LES and RANS CFD code.…”

Large Eddy Simulation for Dispersed Bubbly Flows: A Review

“…In accordance with the earlier work, they confirmed the importance of a suitable lift coefficient and drag law. Moreover, they studied the influence of different spargers (perforated plate, sintered plate, and single hole) and turbulence models (k-, RSM, and LES) using the experimental data of Bhole et al [52]. The main findings from the study were that the RSM performs better than the kmodel; the LES was successful in predicting the averaged flow behaviour and was able to simulate the instantaneous vortical-spiral flow regime in the case of a sieve plate column, as well as the bubble plume dynamics in case of single-hole sparger.…”