Numerical Simulation Of Gas-liquid Flow Research Articles

Numerical simulation of gas-liquid flow in inclined shale gas pipelines

Corrosion and perforation accidents often occur in shale gas gathering pipelines, which causes serious economic losses. The accumulation laws and flow field of shale gas gathering pipelines are revealed by OLGA and ANSYS Fluent simulation. Under different working conditions, the gas entering the pipeline contains 1.3∼3.1% water, which will condense in the pipelines with the decrease of temperature and form effusion. The effusion is mostly distributed in low-lying places and climbing pipe sections, which is consistent with the location of corrosion perforation. Through the three-dimensional simulation of the local upward pipe section, the effusion pipe will form vortices to accelerate the corrosion mass transfer. Further combine the high-temperature and high-pressure reactor experiment, the flowing causes of corrosion failure of shale gas gathering pipelines in the lower part of upward inclined pipeline sections are determined. Therefore, the lower part of the upward inclined pipeline section is a high-risk corrosion area.

Computational studies of gas-liquid flow in a multi-branch manifold

Three-dimensional, time-dependent numerical simulations of gas-liquid flow in a multi-branch manifold (an idealised model of the header/feeder system of a CANDU nuclear reactor) were carried out using the volume of fluid approach to separate the phases and the detached eddy simulation model to simulate turbulence. Interest was focusse n the distribution of the liquid to different feeders. Numerical results for a header connected to a small number of vertical feeders were in fair agreement with in-house experimental data. The rates of change of liquid discharge following changes of inlet conditions were estimated and found to depend on feeder location. The interface between an upper region of the header that was occupied by mostly air and a lower region that was occupied by an air-water mixture was found to rise with an increase in either air or liquid inlet flow rate. Simulations were performed to quantify the effects of differences in the values of fluid properties of air-water mixtures at approximately standard atmospheric pressure and temperature from those of saturated steam-water mixtures at significantly higher pressures (up to 10 MPa) and temperatures (up to 310 °C). The liquid flow rate through a feeder that was directly below the header inlet was found to decrease markedly with increasing mixture pressure and temperature. Pilot simulations of air-water flows in a header connected to multiple feeders with inlets at different elevations and orientations revealed that, under certain conditions, some of these feeders discharged little liquid.

Numerical Simulation of Gas-Liquid Flow in a Bubble Column by Intermittent Aeration in Newtonian Liquid/Non-Newtonian Liquid

The dynamic behaviors of gas-liquid two-phase flow were simulated in a lab-scale intermittent bubble column by Euler-Euler two-fluid model coupled with the PBM (population balance model) using two different liquid phases, i.e., Newtonian fluid (water)/non-Newtonian fluid (activated sludge). When non-Newtonian fluid was used during intermittent aeration, some interesting results were obtained. Two symmetric vortexes existed in the time-averaged flow field; the vertical time-averaged velocity of the liquid phase decreased with increasing anaerobic time; the average gas holdup distribution was like a trapezoid with long upper side and short lower side and affected by the dynamic viscosity of the liquid phase. Compared with non-Newtonian fluid, the use of Newtonian fluid as the liquid phase led to a more complicated time-averaged flow field structure and vertical time-averaged velocity distribution, higher average gas holdup, and the asymmetric column-shaped gas holdup distribution with increasing anaerobic time. For different liquid phases, the instantaneous flow field, instantaneous vertical velocity, and instantaneous gas holdup distribution all periodically changed with anaerobic time; however, different from Newtonian liquid phase, non-Newtonian liquid phase had no periodic oscillating instantaneous horizontal velocity.

Numerical simulation of gas-liquid flow through a 90° duct bend with a gradual contraction pipe

The effect of a gradual contraction pipe (GCP) on gas-liquid flow in a circular-sectioned horizontal to vertical 90° duct bend was investigated by computational fluid dynamics (CFD) simulation. The hydrodynamics of gas-liquid flow in 90° duct bends with and without a GCP in the vertical section were compared using a 3D steady Eulerian-Eulerian approach. The predicted static pressure in the vertical section of the pipes and the pressure drop in the whole pipe were consistent with experimental data. Results of simulations showed that liquid could distribute more uniformly at the exit of the pipe with a GCP. The increased uniformity was accompanied by an increase in pressure drop by a factor of less than 10% compared to the pipe without a GCP. The position of minimum pressure in the bend was changed by the GCP. A GCP can alter the trajectories of the fluid and secondary flow. As a result, the fluid can quickly reach a steady state downstream from the bend.

Numerical Simulation of Gas-Liquid Flow in Hydrocyclone

Hydrocyclone is one of wildly used water treatment equipments in industry field, which separates solid particles from waste water through centrifugal force. Numerical researches about particles separating in hydrocyclone are abundant and mature, but ones about gas-liquid tow phase flow are rare. In this paper, gas-liquid flow in hydrocyclone was simulated with VOF model, which successfully solved a problem about sediment clearance of hydrocyclone in one steel plant. This research saved huge reconstruction investment for the plant, and reduced construction period which abated influence on production progress.

Numerical Simulation and Analysis of Gas-Liquid Flow in a T-Junction Microchannel

Gas-liquid flow in microchannels is widely used in biomedicine, nanotech, sewage treatment, and so forth. Particularly, owing to the high qualities of the microbubbles and spheres produced in microchannels, it has a great potential to be used in ultrasound imaging and controlled drug release areas; therefore, gas-liquid flow in microchannels has been the focus in recent years. In this paper, numerical simulation of gas-liquid flows in a T-junction microchannel was carried out with computational fluid dynamics (CFD) software FLUENT and the Volume-of-Fluid (VOF) model. The distribution of velocity, pressure, and phase of fluid in the microchannel was obtained, the pressure distribution along the channel walls was analyzed in order to give a better understanding on the formation of microbubbles in the T-junction microchannel.

Numerical simulations of fluid dynamics and mixing in a large shallow bubble column: effects of the sparging pipe allocations for multiple-pipe gas distributors

Numerical simulations of gas-liquid flow in a bubble column of 800 mm in diameter using two-fluid model and multi-size-group (MUSIG) model were conducted to investigate the effect of allocation of sparging pipes in gas distributors on hydrodynamic flow, gas hold-up, mixing characteristics, turbulence and bubble size. In the simulation, six different arrangements were assessed, which four-sparging pipes are mounted to a gas distributor with the allocation ring to bubble column ratios (d/DT) being 0.3, 0.37, 0.4, 0.5, 0.6 and 0.7, respectively. The simulation results have clearly demonstrated that the allocation of sparging pipes to the gas distributor has an important impact on gas hold-up and mixing characteristics. It was found from the simulations that the mixing time and overall gas hold-up increase initially with the increase of d/DT but decrease with further increase of d/DT. As a result, it was revealed that the optimum value of d/DT is around 0.4 for the highest overall gas hold-up and is confirmed by the experiment. It was also indicated from the simulation that d/DT of 0.5 yields the maximum mixing time.