Numerical Study on the Erosion Characteristics of U-Type Bend for Gas Solid Flow

2017 ◽  
Author(s):  
Yu Wang ◽  
Qi He ◽  
Ming Liu ◽  
Weixiong Chen ◽  
Junjie Yan
Keyword(s):  
Particle Size ◽  
Erosion Rate ◽  
Loading Rate ◽  
Pipe Wall ◽  
Numerical Study ◽  
Pulverized Coal ◽  
Mass Loading ◽  
Two Phase ◽  
Inlet Velocity ◽  
Pipe System

In pulverized coal-fired plant, the U-type bend is commonly used in flue gas and pulverized coal pipe system to due to the constraints of outer space. And gas-solid two-phase flow exists in these pipelines. The erosion of the pipe has significant effect on the safety and reliability of pipelines. In present paper, the erosion characteristics of U-type bend were investigated through CFD (Computational Fluid Dynamics) method. The wear distribution on the pipe wall was obtained. And the particle flow characteristics in U-type bend were analyzed. The influence of inlet velocity, mass loading rate and particle size on the erosion rate was studied as well. Result suggested that the maximum erosion rate increases exponentially with the increase of inlet velocity. And maximum erosion rate increases linearly with the increasing mass loading rate. Increasing particle size can aggravate the wear on the pipe wall.

Particle Behaviors Under Acceleration Condition in Solid-Air Two Phase Flow

2010 ◽  
Author(s):  
Tong Zhao ◽  
Masahiro Takei
Keyword(s):  
Particle Size ◽  
Particle Acceleration ◽  
Loading Condition ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Phase Flow ◽  
Particle Loading ◽  
Initial Particle ◽  
Two Phase ◽  
Calculation Region

This paper presents a numerical study of the particle behaviors under acceleration conditions in the solid-air two-phase flow by means of a combined two-dimensional model of computational fluid dynamics and discrete element method (CFD-DEM). The simulation model provides the information regarding the particle distribution behaviors within the calculation region and the particle run-out rate from the calculation region under different parameter conditions, such as particle size, initial particle loading and particle acceleration condition. The results demonstrate that the particle run-out rate is directly influenced by the particle size and the initial loading condition. The particle acceleration in the horizontal direction adversely affects the particle run-out rate when the initial particle loading condition is dispersed and uniform. However, this adverse effect disappears when the initial particle loading condition becomes concentrate and partial.

Experimental and numerical study on gas-solid two-phase flow through regulating valve of pulverized coal flow

2020 ◽  
Vol 155 ◽  
pp. 1-11 ◽  
Author(s):  
Meihua Chen ◽  
Haifeng Lu ◽  
Yong Jin ◽  
Xiaolei Guo ◽  
Xin Gong ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Numerical Study ◽  
Pulverized Coal ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Through ◽  
Coal Flow

Experimental and numerical study of air-water flow characteristics in a horizontal duct

2020 ◽  
pp. 095440622093631
Author(s):  
Mohamed H Mansour ◽  
Ali A Zahran ◽  
Lotfy H Rabie ◽  
Ibrahim M Shabaka
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Phase Distribution ◽  
Electronic Device ◽  
Pipe Wall ◽  
Numerical Study ◽  
Bubble Velocity ◽  
Phase Flow ◽  
Two Phase

The horizontal bubbly two-phase flow is preferably used in various industrial applications because it provides high interfacial areas which enhance the heat and mass transfer. In the present research, the phase distribution of controlled air-water flow in a horizontal acrylic round pipe with 60 mm inside diameter (D) has been investigated experimentally and modeled numerically. The modeled differential pressure and the mixture velocity profile at a distance of 33D from the mixing section (fully developed region) are computed numerically and compared with those obtained experimentally from the two-phase flow system established and maintained at the National Institute of Standards (NIS-Egypt). Furthermore, the numerical and the experimental data have been compared with previous correlations and models. Reasonable quantitative agreement between all data is found. An electronic device based on Arduino Uno board was designed and used with careful data manipulation for measuring the slug bubble velocity. The results point out that the air volume fraction has a maximum value at the upper pipe wall as the gas bubbles tend to migrate to the upper wall. A new correlation was obtained for bubble migration length to the upper pipe wall which is very important in chemical industrial processes and other engineering application.

A Numerical Study of Sand Particle Erosion in Elbow and a Series of Plugged Tees in Gas-Particle Two-Phase Flow

2018 ◽  
Author(s):  
A. Farokhipour ◽  
Z. Mansoori ◽  
M. Saffar-Avval ◽  
M. A. Rasoulian ◽  
A. Rasteh ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Fine Particles ◽  
Numerical Study ◽  
Simple Algorithm ◽  
Sand Particle ◽  
Particle Erosion ◽  
Two Phase ◽  
Natural Gas Pipelines ◽  
Sand Erosion ◽  
Sst Turbulence Model

Sand particle erosion is the main cause of the failure of bends in the natural gas pipelines. The rapid progress of computational power and modern numerical methods has provided the opportunity for developing realistic simulation of the erosion process. The goal of this paper is to predict the sand erosion rates with the use of computational fluid dynamics in the gas/solid flows in the plugged tees and standard elbows. For this purpose, the Eulerian-Lagrangian approach was used. To simulate the flow, the SIMPLE algorithm and the k-ω SST turbulence model were used. Particles were injected into the inlet pipe with different sizes. To predict more realistic results the Grant and Tabakoff stochastic rebound model was applied and the Oka model was used to calculate erosion. The results showed that, the use of plugged tee instead of a standard elbow would reduce the erosion rate only for fine particles. Also, for them, by increasing the plugged length the pipe will experience less erosion. For coarser particles, however, the vortex created in the plugged section did not affect the particles velocity; therefore, the erosion rate was not reduced.

Numerical Study of Transient Conjugate Heat Transfer in a Long Two-Phase Pipeline

2000 ◽  
Author(s):  
Yuri V. Fairuzov ◽  
Hector Arvizu Dal Piaz
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Conjugate Heat Transfer ◽  
Pipe Wall ◽  
Numerical Study ◽  
Electrical Heating ◽  
Practical Significance ◽  
Local Thermal Equilibrium ◽  
Working Fluid ◽  
Two Phase

Abstract A growing number of multiphase technology applications stimulate the development of reliable methods for modeling transient processes in two-phase systems in which the temperature field in the moving fluid and the temperature field in the bounding walls are directly dependent on each other. This situation presents a conjugate heat-transfer problem since the heat-transfer rate at the wall-fluid interface and local fluid conditions are not known a priori, and therefore need to be simultaneously calculated. Examples of such processes include the direct heating of multiphase pipelines, a change of heat load in evaporators of two-phase thermal control systems, startup or shutdown of systems with a two-phase working fluid. In this paper, direct electrical heating of a long two-phase pipeline has been modeled. The modeling of transient two-phase flow and heat transfer in the pipeline is based on two different mathematical formulations. In the first formulation, the transient heat conduction and the forced convection effects are rigorously taken into account. The second formulation assumes that the pipe wall and the fluid are in local thermal equilibrium. The effect of the thermal capacity of the pipe wall is taken into account by an additional term in the energy equation for the fluid flow. Such an approach allows significant simplifying the problem and reducing the computer running time. Numerical simulation of the sudden heat input to the pipe wall has been performed using both formulations of field equations. The practical significance of the results obtained is discussed.

scholarly journals Erosion processes during non-stationary cavitation of irrigation pumps

2021 ◽  
Vol 264 ◽  
pp. 03016
Author(s):  
A Dzhurabekov ◽  
Sh Rustamov ◽  
N Nasyrova ◽  
J Rashidov
Keyword(s):  
Particle Size ◽  
Water Flow ◽  
Erosion Rate ◽  
Two Phase ◽  
Size Limit ◽  
Minimum Value ◽  
Erosion Processes ◽  
Effect Of Particle Size ◽  
Working Bodies ◽  
Pumping Units

The article gives the main results of the study of the dynamics of wear of the working bodies of irrigation pumps, gives the main recommendations as a result of the study of pumping units in the presence of cavitation. The authors consider the cavitation coefficient as the minimum value of this expression, at which the beginning of cavitation is detected. The process of unsteady cavitation is accompanied by many significant effects in which the water flow becomes two-phase, with a corresponding change in its properties, which affects the pump's efficiency. The effect of particle size on the erosion rate is predominant only up to a certain size limit, i.e., 600-800 microns on the blades. After that, the erosion rate increases with a comparatively slower rate. This indicates that the particle size affects the erosion rate only up to a certain particle size.

Experimental Study of Particle Size, Sound Velocity, and Resonance Phenomena in a Two-Phase Foam Flow

2001 ◽  
Vol 32 (4-6) ◽  
pp. 5
Author(s):  
A. P. Sevast'yanov ◽  
I. V. An ◽  
S. I. Vainshtein ◽  
Yu. A. Sevast'yanov ◽  
A. V. Sidnev ◽  
...  
Keyword(s):  
Experimental Study ◽  
Particle Size ◽  
Sound Velocity ◽  
Two Phase ◽  
Foam Flow ◽  
Resonance Phenomena

Further Computational Investigations Into Aero-Engine Bearing Chamber Off-Take Flows

2010 ◽  
Author(s):  
Adam Robinson ◽  
Carol Eastwick ◽  
Herve´ Morvan
Keyword(s):  
Experimental Work ◽  
Symmetry Plane ◽  
Two Phase ◽  
Pipe System ◽  
Aero Engine ◽  
Gravity Driven ◽  
Computational Fluid Dynamics Cfd ◽  
Modelling Assumptions ◽  
Static Head ◽  
Engine Bearing

Within an aero-engine bearing chamber oil is provided to components to lubricate and cool. This oil must be efficiently removed (scavenged) from the chamber to ensure it does not overheat and degrade. Bearing chambers typically contain a sump section with an exit pipe leading to a scavenge pump. In this paper a simplified geometry of a sump section, here simply made of a radial off-take port on a walled inclined plane, is analysed computationally. This paper follows on work presented within GT2008-50634. In the previous paper it was shown that simple gravity draining from a static head of liquid cold be modelled accurately, for what was akin to a deep sump situation fond in integrated gear boxes for example. The work within this paper will show that the draining of flow perpendicular to a moving film can be modelled. This situation is similar to the arrangements found in transmission bearing chambers. The case modelled is of a walled gravity driven film running down a plane with a circular off-take port, this replicates experimental work similar to that reported in GT2008-50632. The commercial computational fluid dynamics (CFD) code, Fluent 6 [1] has been employed for modelling, sing the Volume of Fluid (VOF) approach of Hirt and Nichols [2, 3] to capture the physics of both the film motion and the two phase flow in the scavenge pipe system. Surface tension [4] and a sharpening algorithm [5] are used to complement the representation of the free surface and associated effects. This initial CFD investigation is supported and validated with experimental work, which is only depicted briefly here as it is mainly sued to support the CFD methodology. The case has been modelled in full as well as with the use of a symmetry plane running down the centre of the plane parallel to the channel walls. This paper includes details of the meshing methodology, the boundary conditions sued, which will be shown to be of critical importance to accurate modelling, and the modelling assumptions. Finally, insight into the flow patterns observed for the cases modelled are summarised. The paper further reinforces that CFD is a promising approach to analysing bearing chamber scavenge flows although it can still be relatively costly.

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