two phase flow

Transportation of liquid energy carriers by pipelines is accompanied by obligatory commodity-transport operations, in particular - determination of the volume of the pumped product. In the process of operation there are complicated sections of pipelines - gravity pipelines, where the determination of the filling factor is practically impossible. In order to solve the problem, the most probable flow patterns of multiphase flow in the pipeline were determined using Ansys software. Then the approach was developed through determination of the flow pattern inside the pipeline using the previously developed computer program, which includes determination of the filling level of the pipeline by the Newton-Gauss method, determination of one of 8 classes of the flow pattern and recalculation of the filling factor of the pipe body. The result of the research was the developed computer vision model using the resnet-50 architecture. The possibility of determining the oil flow regime at an acceptable high level has been established. The performance of this model was evaluated through an acceptable ROC-AUC value for each class (all metrics were above 0.5, namely, almost all classes have a value of 0.8, which is high for this kind of multiclass classification). Based on the results of the work, a stand and a prototype control board has been proposed, with which it will be possible to obtain digital analogues of images of each mode and automate the process of determining the flow mode. A scheme is proposed for improving the oil metering unit by adding a module for calculating the filling factor. It is planned to conduct a full-scale experiment and assemble a control board and a stand, also proposed in the sketch format in this article.

In case of poor-quality oil refining in the oil pipeline, water accumulations are formed, increasing hydraulic losses during transportation and contributing to corrosion processes. Hydrodynamic cleaning, which uses pumped oil flow, has been investigated due to its cost-effectiveness and adaptability for pipelines of varying diameters. This study develops a finite element hydrodynamic model to simulate the removal of water accumulations from inclined pipelines (inclination angle α = 45°). The model reveals a clear relationship between inlet velocity and multiphase flow patterns, demonstrating transitions from stratified flow (ST) at velocities below 0.1 m/s, to stratified with mixing (ST&MI) at 0.1–0.2 m/s, and finally to a dispersed water-in-oil (DW/O) pattern beyond 0.2 m/s. These velocity transitions are achieved in controlled steps: a steady increase to 0.1 m/s within 20 seconds, followed by acceleration phases reaching 0.25 m/s by 100 seconds. The DW/O regime exhibits the highest cleaning efficiency, reducing water volume from 660 ml to 273.29 ml over 125 seconds—a 58.5% reduction. The analysis further shows an initial rise in pressure gradient within the ST regime, peaking during the first plateau (0.1 m/s) before stabilizing and significantly declining in the DW/O regime at velocities exceeding 0.25 m/s. These findings emphasize the importance of optimizing flow velocity to achieve effective water removal while minimizing hydraulic losses. The study also highlights limitations in existing experimental setups, which predominantly use small diameters (<50 mm), and underscores the need for larger-scale experiments to validate these findings in real-world pipeline operations.

Through this paper, a 3D simulation together with experimental observation was conducted to study two-phase flow in a vertical tube. OpenFOAM software was employed to analyze air and water. Main flow stream was downward which was considered to be within a vertical pipe of 10 mm in diameter. Study included two inputs for flows: upper input for water and side input for air. Several states with various mass fluxes for both water and air were studied. Based on physics of the issue, numerical simulation was considered to be time-dependent. Obtained results showed that when air velocity occupied lower values, air momentum cannot overcome water momentum leading in small slugs. When airflow velocity was more than water flow rate, it dominated water flow and consequently could affect mainstream direction. Also, velocity graphs on centerline represented that going forward in time, velocity magnitude experiences a significant value of fluctuations and large oscillations occur next to outlet. Comparing experimental and numerical results, approximately 9% differences can be found which showed suitable agreement. Results showed that at initial steps, void fraction faces a significant jump in values. Intensity of this change in void fraction values was higher in lower water velocity. Indeed, by increment of water velocity, inertial forces associated with liquid phase find a dominant role in overall hydrodynamics of the gas-liquid flow. Also, it is obvious that flowing manner in cases 1, 2, and 3 are similar but after case 4, flow pattern varies. These changes are more considerable in cases 5 and 6.

In this research, steady-state Mixture and Eulerian-Eulerian method for liquid-gas parallel flow ejector have been examined. The simulation demonstrated that the Mixture model simulation represents better and efficient. The Eulerian-Eulerian model needed longer computational time and had a complexity to achieve the optimal convergence. However, both methods' performances were shown slightly similar. The models indicated a difference of about 6% in the flow rate ratio, their pressure diagrams nearly coincide, and their velocity parameter varies by 7% by comparing to the existing experimental data. Additionally, the Mixture model results appropriately conformed much better to the experimental data. So, the Mixture model was chosen for futher parametric study. Simulation results indicated that the flow rate ratio decreases by increasing the throat's cross-sectional area, and the flow rate ratio increases by increasing the nozzle's cross-sectional area. In this regard, e.g., the flow rate ratio of ejector by increasing pressure from 70 to 80 kPa, the air inlet increases up to 94%, and by increasing ejector outlet pressure, the flow rate ratio reduces such that no suction can be observed at 160 kPa. Consequently, in the 150 kPa pressure ratio, the flow rate ratio was reduced by almost 100%.

In the present paper, the heat transfer and fluid velocity between two horizontal plates is examined in existence of magnetic parameter. The parameters such as magnetic fluid flow, viscosity, Brownian motion, and thermo-phoretic have been investigated according to this analysis. The innovation of this paper is using two analytical methods for calculate differential equations and comparison these results together. In this paper, the effects of magnetic field on fluid flow for industrial use are investigated. The effects of magnetic field on fluid flow are surveyed by using the Variation Iteration Method (VIM) and the Adomian Decomposition Method (ADM) and compare these methods with the numerical Runge-Kutta method. According to results, increasing the values of the magnetic parameter, the fluid velocity decreased and the fluid viscosity increased. Also, Brownian motion and thermo-phoretic parameters were directly related to the coefficient of friction. The Brownian motion of nanoparticles results in the thermophoresis phenomenon, and increasing both Brownian motion and thermophoresis causes an increase in temperature.

In this paper, a numerical study is conducted in order to compare hyperbolic range of equations of isotherm two-fluid model governing on two-phase flow inside of pipe using conservative Shock capturing method. Differential equations of the two-fluid model are presented in two forms (i.e. form I and form II). In forms I and II, pressure correction terms are hydrodynamic and hydrostatic, respectively. In order to compare, the hyperbolic range of equations of two-fluid model is presented in two forms. One case (water Faucet Case) in the vertical configuration and two other cases (i.e. Large Relative Velocity Shock Tube Case and Toumi’s Shock Tube Case) in the horizontal configuration were used. The form I of two-fluid model had broader range of well-posing than form II of two-fluid model. The form I of two-fluid model has coefficient that proper selecting of this coefficient ensures hyperbolic roots of the characteristic equation, but in form II, roots of the characteristic equation did not have this capability.