The article describes a three-dimensional simulation of the stationary motion of the gas and condensed phase particles of varying severity in a curvilinear orthogonal coordinate system of channels of gas pipelines. A numerical method for solving the equations that describe the motion of the particles, based on obtaining difference schemes and the use of a two-level iterative process. Built a multi-dimensional mathematical model of the steady flow of viscous gas hydrate particles in equilibrium axisymmetric taking into account transport and energy dissipation. Numerical calculations of the velocity field and the dispersed gas phase trajectory of mass flow of particles deposited on the walls of various sizes in a wet gas flow in a curved pipe

A. N. Krasnov

V. E. Lyalin

English

Vibroengineering PROCEDIA

 278 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533  
Modeling of flow two-phase mixture in curved channel 
pipeline 
V. E. Lyalin1, A. N. Krasnov2 
1Kalashnikov Izhevsk State Technical University, Izhevsk, Russia 
2Ufa State Petroleum Technological University, Ufa, Russia 
1Corresponding author 
E-mail: 1velyalin@mail.ru, 2ufa-znanie@mail.ru 
(Accepted 7 October 2015) 
Abstract. The article describes a three-dimensional simulation of the stationary motion of the gas 
and condensed phase particles of varying severity in a curvilinear orthogonal coordinate system 
of channels of gas pipelines. A numerical method for solving the equations that describe the 
motion of the particles, based on obtaining difference schemes and the use of a two-level iterative 
process. Built a multi-dimensional mathematical model of the steady flow of viscous gas hydrate 
particles in equilibrium axisymmetric taking into account transport and energy dissipation. 
Numerical calculations of the velocity field and the dispersed gas phase trajectory of mass flow 
of particles deposited on the walls of various sizes in a wet gas flow in a curved pipe. 
Keywords: model of gas flow, curved channels pipeline, gas dispersed particles, air cooling. 
1. Development of a model of hydrate formation in the flow of raw natural gas in the pipes 
On gas and gas condensate fields have been widely used air-cooling. They can be installed 
after the installation of complex preparation of gas booster station and at other sites. 
Blocks air coolers used on gas fields consist of 10-16 units. Each unit has three longitudinal 
sections of heat exchangers with six rows of horizontal finned tubes. In each row of thirty 
(twenty-nine) tubes arranged in staggered rows. The flow of cold air from the bottom up through 
the six series created by two fans placed on a foundation under the tubular section. 
Apparatuses for the air cooling operation without hydrate satisfactorily cooled dehydrated 
natural gas and crude gas at positive ambient temperatures (in the absence of hydrate formation). 
However, in winter conditions during the cooling of the crude gas after the first stage of the gas 
booster station receive a number of problems. The bottom row of tubes, as a result of local 
supercooling gas, there are conditions for the formation of hydrates; on the inner wall of heat 
exchange tubes formed hydrates, ice, and the individual tubes are destroyed. 
To prevent the formation of hydrates while cooling the crude gas in the pipes of air-cooling in 
practice is necessary to maintain a sufficiently high average gas temperature at the outlet of the 
apparatus, sometimes up to 18-20 °C, thereby limiting not only the potential of air cooling, but 
and reducing the quality of the gas being prepared for transport. A particularly acute problem of 
the quality of training in terms of gas dew point of moisture in a falling reservoir pressure. 
The main purpose of air coolers, cooling the crude gas, have a minimum temperature of the 
gas supplied to the drying in preparing him to further transport. This temperature must not be 
lower than the temperature of hydrate formation inside the raw gas-cooled heat exchanger tubes 
most in stationary cooling mode and can be lower than the temperature of hydrate formation at 
unsteady cooling, when applying pre-drying and the hydrate formation inhibitor supply tube in 
the lower rows. 
A necessary condition for the formation of crystalline hydrates is the presence of moisture in 
the gas is condensed. The moisture content of the gas is the ratio of mass amount of moisture 
contained in the wet gas to the mass amount of dry gas. In case of exceeding the dew point 
temperature of the gas pipeline in the form of gas conditions for the formation of crystalline 
hydrates. During transport in cold weather conditions for hydrate formation primarily appear on 
the tube wall, where it is condensed particle deposition. Therefore, it is advisable to consider the 
multi-dimensional structure of the flow of raw gas, affects the process of hydrate deposits on the 
MODELING OF FLOW TWO-PHASE MIXTURE IN CURVED CHANNEL PIPELINE.  
V. E. LYALIN, A. N. KRASNOV 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533 279 
walls. 
A mathematical model based on the stationary equations of viscous flow recorded in 
axisymmetric [1]: 
(ݕߩݑ)௫ + (ݕߩݒ)௬ = 0, 
(ݕߩݑݑ)௫ + (ݕߩݑݒ)௬ = −ݕ݌௫ + (ݕߤݑ௫)௫ + ൫ݕߤݑ௬൯௬ + ݕ൫ߤ௫ݑ௫ + ߤ௬ݒ௫൯, 
(ݕߩݑݒ)௫ + (ݕߩݒݒ)௬ = −ݕ݌௬ + (ݕߤݒ௫)௫ + ൫ݕߤݒ௬൯௬ + ݕ ൬ߤ௫ݑ௬ + ߤ௬ݒ௬ − ߤ
ݒ
ݕଶ൰, 
(ݕݑܶ)௫ + (ݕݒܶ)௬ = ൬ݕ
ߤ
ߪ் ௫ܶ൰௫
+ ൬ݕ ߤߪ் ௬ܶ൰௬
, 
(ݕݑݓ)௫ + (ݕݒݓ)௬ = ൬ݕ
ߤ
ߪ௪ ݓ௫൰௫
+ ൬ݕ ߤߪ௪ ݓ௬൰௬
+ ܬ௪, 
(ݕݑ݃)௫ + (ݕݒ݃)௬ = ቆݕ
ߤ
ߪ௚ ݃௫ቇ௫
+ ቆݕ ߤߪ௚ ݃௬ቇ௬
+ ܬ௚, 
(ݕݑܭ)௫ + (ݕݒܭ)௬ = ൬ݕ
ߤ
ߪ௄ ܭ௫൰௫
+ ൬ݕ ߤߪ௄ ܭ௬൰௬
+ ݕߩ(ܤ − ߝ), 
(ݕݑߝ)௫ + (ݕݒߝ)௬ = ൬ݕ
ߤ
ߪఌ ߝ௫൰௫
+ ൬ݕ ߤߪఌ ߝ௬൰௬
+ ߩߝ ܿଵܤ − ܿଶߝܭ , 
(1) 
where ߩ – density of the gas; ܲ – pressure; ݑ, ݒ  – velocity components on the axis ݔ , ݕ; ߤ – 
coefficient of dynamic viscosity; ܶ – gas temperature; ݓ, ݃ – moisture content of hydrates in the 
flow; ߪ், ߪ௪, ߪ௚ – Prandtl and Schmidt numbers; ܴ஼ – gas constant of a mixture of combustion 
products. The density is determined from the equation of state ߩ = ݌ (ܴ஼ܶ)⁄ . 
The system of equations of motion is considered in conjunction with the transport equations 
of the kinetic energy ܭ and the dissipation rate ߝ. The viscosity ߤ is determined by the sum of  
ߤ = ߤ௠ + ߤ், where ߤ௠, ߤ் – coefficients of molecular and turbulent viscosity, ܤ, ܿଵ, ܿଶ, ܿఓ – 
empirical coefficients, ߤ் = ܿఓߩ ܭଶ ߝ⁄ . 
Mass transfer speed of water in the hydrates and the rate of formation of hydrates is defined 
source terms ܬ௪, ܬ௚. The possible formation of hydrates (when the content of free water in the gas, 
that is, provided that the gas temperature is lower the dew point temperature ௥ܶ and greater than 
the temperature of phase transition ௙ܶ ) increases with increasing pressure and decreasing 
temperature gas. Mass rate of hydrate formation is taken proportional to the difference between 
the gas temperature and the temperature of the beginning of the formation of hydrates ௚ܶ. 
ܬ௪ = ቐ−ܣ௪ݓ
௚ܶ − ܶ
௚ܶ − ௙ܶ ,
0    |    ܶ < ௚ܶ, ܶ < ௥ܶ, ܶ > ௙ܶ,
 
ܬ௚ = ቐܣ௚ݓ
௚ܶ − ܶ
௚ܶ − ௙ܶ ,
0    |    ܶ < ௚ܶ, ܶ < ௥ܶ, ܶ > ௙ܶ.
 
(2) 
1.1. Border conditions 
At the entrance to the pipe at ݔ = 0  a given initial flow parameters ݑ଴ = ܩ (ߨܴଶ)⁄ ,  
ݒ଴ = 0, ܶ଴, ݓ଴, ݃଴ = 0, ܭ଴, ߝ଴. On the wall of the pipe when ݕ = ܴ: the conditions for trapping 
ݑ, ݒ, ܭ, ߝ; for temperature: 
MODELING OF FLOW TWO-PHASE MIXTURE IN CURVED CHANNEL PIPELINE.  
V. E. LYALIN, A. N. KRASNOV 
280 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533  
ߣ ∂ܶ(ݔ, ܴ)∂ݕ = ߙ଴൫ ଴ܶ − ܶ(ݔ, ܴ)൯,
∂ݓ
∂ݕ = 0,
∂݃
∂ݕ = ݉௚. (3)
 
Fig. 1. The calculated distribution hydrate content 
By ݉௚ < 0 hydrates is deposited on the pipe wall. On the border of the output ݔ = ܮ set “soft” 
conditions, consistent with the vanishing of the second derivatives of all variables. 
The system of equations is solved numerically Patankar’s SIMPLE [2]. The distribution of 
content of the gas hydrates in the cross section and length of the pipe obtained by calculation, 
shown in Fig. 1. 
We consider a section of pipe at an inlet pressure of 0.5 MPa. A characteristic feature of the 
course is the existence of conditions for the formation of hydrates in the wall region, even in the 
initial section of the pipe. With increasing distance of hydrate formation zone is expanded and 
extends to the entire cross section of the tube. Humidity gas decreases as the water binding 
hydrates. The inhomogeneous distribution of the content of hydrates of the pipe section, the results 
obtained by the two-dimensional gas-dynamic calculations significantly affects the nature of the 
hydrate deposits on the pipe walls. Primarily hydrates are formed in the vicinity of the wall. The 
low velocity of the gas in the laminar sublayer and a high content of gas hydrates in the hydrate 
promote sticking to the wall. 
2. The mathematical model of non-equilibrium flow of natural gas from the condensed phase 
in the channels of complex shape 
Besides the effect of deposits on the walls of pipes, the solid particles can have an abrasive 
effect on the structural elements and measuring the gas shutoff apparatus. The condensed phase 
in the flow of natural gas hydrates in addition may contain other particulate matter (scale, sand, 
etc.). The assessment of such effects can be carried out on the basis of solving the equations of 
motion of a two-phase mixture in the pipeline elements. 
The equations for the dispersed phase recorded in the curvilinear coordinate system [1]: 
(ܬݎఊ݊ݑ௦)క + (ܬݎఊ݊ݒ௦)ఎ = 0, 
ܬݎఊߩ௦ݑ௦ݑ௦)క + (ܬݎఊߩ௦ݒ௦ݑ௦)ఎ + ݎఊߩ௦ݒ௦ݑ௦ܬఎ − ݎఊߩ௦ݒ௦ݒ௦ܬక = ܬଶݎఊܳଶ, 
ܬݎఊߩ௦ݑ௦ݒ௦)క + (ܬݎఊߩ௦ݒ௦ݒ௦)ఎ + ݎఊߩ௦ݒ௦ݑ௦ܬక − ݎఊߩ௦ݒ௦ݒ௦ܬఎ = ܬଶݎఊܳଷ, 
ܬݎఊߩ௦ݑ௦ܧ௦)క + (ܬݎఊߩ௦ݒ௦ܧ௦)ఎ = ܬଶݎఊܳଵ, 
(ܬݎఊ݊௦ݑ௦)క + (ܬݎఊ݊௦ݒ௦)ఎ = 0, 
(4)
MODELING OF FLOW TWO-PHASE MIXTURE IN CURVED CHANNEL PIPELINE.  
V. E. LYALIN, A. N. KRASNOV 
 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533 281 
where the index ݏ belongs discontinuous phase; ܿ௦, ߩ௟ – heat capacity and density of the material 
drops; ݊ – the number of condensed particles in unit volume; ܤ௨, ܤ் – coefficients of resistance 
and heat transfer between phases, is given by [2]: 
ܤ௨ =
9ߤ
2ߩ௟ݎ௦ଶ ݂, ݂ = 1 + 0.25√Re + 0.0117Re, Re =
|ܞ − ܞ௦|ݎ௦ߩ
ߤ , (5) 
ܤ் =
ܤ௨ܰݑܿ௣
3Prܿ௦݂ , ܰݑ = 2 + 0,459Re
଴,ହହPr଴,ଷଷ. (6) 
To solve the equations that describe the movement of particles, constructed difference scheme 
that monitors the flow direction. To solve the differential equations used a two-level iterative 
process. As an initial approximation for the particle velocities are taken of the gas velocity. A 
numerical method allows the calculation of the velocity field of the gas and particulate phase, the 
trajectories of particle motion, the mass flow of particles deposited on the walls. 
The motion of the gas phase was calculated at a Reynolds number 50000. The vector velocity 
field is shown in Fig. 2. 
 
Fig. 2. The velocity field in the curved section of the pipe 
As follows from the results of calculations, the flow field is not symmetric. First, during urged 
toward the small radius wall and then in the opposite direction. As a result, the flow deflection 
from the center of a vortex flow as shown in Fig. 2. The velocity profile is characteristic of 
turbulent profile. 
Particle motion is calculated for an equivalent particle diameter from 10 to 500 microns. The 
trajectories of the particles are shown in Figure 3. Small particles (10 microns) is monitored line 
current and the gas phase with the walls of virtually interacting. Larger particle diameter of 
100 microns collide with the wall of the pipe after the bend. 
 
Fig. 3. The trajectories of particles with a diameter of 300 microns 
Large particles (300 and 500 microns) have a straight path for bending the pipe portion collide 
with the wall, and with high intensity. Low-velocity particles of 300 microns can be trapped vortex 
flow of gas and is in it for some time. Large particles with a diameter 500 microns almost all come 
through the vortex. Only particles from the wall region with a very low speed to make a whirlwind 
MODELING OF FLOW TWO-PHASE MIXTURE IN CURVED CHANNEL PIPELINE.  
V. E. LYALIN, A. N. KRASNOV 
282 © JVE INTERNATIONAL LTD. VIBROENGINEERING PROCEDIA. OCT 2015, VOLUME 6. ISSN 2345-0533  
return movement. 
As a result of solving the problem of the motion of a two-phase mixture of particles and gas 
pipes are designed curved portion of the mass flow of the wall falling on particles of different 
sizes. Fig. 4 shows the distribution of the mass flows of precipitating particles ܩ in several sizes. 
Coordinates ܵ is measured on the wall of the pipe. Mass flow ܩ is related to the mass flow rate of 
particles on a straight section of the pipe (ߩ௦ ௦ܹ). These data can be used to assess mechanical action 
of the particles on the pipeline wall at different degrees of drying of natural gas. 
 
Fig. 4. Distribution of mass flows deposited particles on the pipe walls 
3. Conclusions 
A model of hydrate formation during the flow channels of raw gas, based on the equations of 
hydrodynamics and heat transfer in axisymmetric. Accounting for two-dimensional effects of 
hydrate formation allows to specify the start of hydrate formation in pipelines, the relative 
deviation of the one-dimensional calculation of two-dimensional averaged 100 %. 
A method for evaluating loss of the condensed phase in the movement of natural gas, using 
the results of the joint numerical solution of the equations for the gas and condensed phases in the 
two-dimensional formulation. Calculation of the particle trajectories in the processing equipment 
indicates to the possibility of abrasion or parts located in the flow or intense sticking and 
accumulation of condensed phase (hydrate). 
References 
[1] Sekundov A. N. Application of differential equations for the turbulent viscosity and analysis of 
non-self-plane movements. Mathematical Institute of USSR Academy of Sciences, Fluid Dynamics, 
Vol. 5, 1971, p. 114-127. 
[2] Patankar S. Numerical Methods for Solving Problems of Heat Transfer and Fluid Dynamics. 
Energoizdat, 1984, p. 150. 


Modeling of flow two-phase mixture in curved channel pipeline

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Modeling of flow two-phase mixture in curved channel pipeline

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