scholarly journals Kinematic characteristics of two-phase flows in waterjet cutting

Vestnik MGSU ◽  
2019 ◽  
pp. 1610-1618
Author(s):  
Mikhail V. Aleshkov ◽  
Lyudmila V. Volgina
Keyword(s):  
Two Phase Flow ◽  
Volume Density ◽  
Solid Particles ◽  
Flow Density ◽  
Phase Flow ◽  
Hydraulic Transport ◽  
Two Phase ◽  
Waterjet Cutting ◽  
Kinematic Characteristics ◽  
Actual Flow

Introduction. In waterjet cutting, a two-phase flow consisting of water and abrasive solid particles moves at a high average speed. Destruction of hard materials and alloys requires a large force and, therefore, a high flow rate. Such flows differ utterly from natural and well-studied flows in hydraulic transport and hydroprocessing. Determination of kinematic characteristics in the waterjet cutting is an independent task. Materials and methods. The results of field studies to determine the essential kinematic characteristics of the two-phase flow are presented. The conditions of transporting the solid particles, the efficiency of their application in cutting as well as the assessment of energy losses. The revelation of features of the two-phase flows and differences from water flows is a part of engineering calculations aimed at the effectiveness of their use in various fields of activity, including firefighting. Results. The calculations of the two-phase flow heterogranularity, the weighted average density of the particles constituting the solid phase, the flow volume density, and actual flow density were carried out. Calculations of the two-phase flow density were performed by а volume-weight method and by integrating the solid particle density distribution in depth. Conclusions. The paper showed that in waterjet cutting the actual density exceeds the flow volume density by 8.5 % what is lower than the values recommended for hydraulic transport. All the engineering calculations must be conducted using the values of the actual flow density. The kinematic characteristics obtained in this work are the basis for the calculation of additional head losses per 1 meter of a firefighting unit hose during transportation.

Solid–liquid two-phase flow and erosion calculation of butterfly valves at small opening based on DEM method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benliang Xu ◽  
Zuchao Zhu ◽  
Zhe Lin ◽  
Dongrui Wang
Keyword(s):  
Peer Review ◽  
Two Phase Flow ◽  
Solid Particles ◽  
Phase Flow ◽  
Butterfly Valve ◽  
Two Phase ◽  
Content Type ◽  
Small Opening ◽  
Solid Liquid ◽  
The Impact

Purpose The study aims to decrease the effect of solid particles on a butterfly valve, which will cause seal failure and leakage, providing a reference for anti-wear design. Design/methodology/approach In this paper, computational fluid dynamics discrete element method (CFD-DEM) simulation was conducted to study the solid–liquid two-phase flow characteristics and erosion characteristics of a butterfly valve with a different opening. Findings Abrasion at 10% opening is affected by high-speed jets in upper and lower parts of the pipeline, where the erosion is intense. The impact of the jet on the upper part of 20% opening begins to weaken. With the top backflow vortex disappearing, the effect of lower jet is enhanced. Meanwhile, the bottom backflow vortex phenomenon is obvious, and the abrasion position moves downward. At 30% opening, the velocity is further weakened, and the circulation effect of lower flow channel is more obvious than that of the upper one. Originality/value It is the first time to use DEM to investigate the two-phase flow and erosion characteristics at a small opening of a butterfly valve, considering the effect of inter-particle collision. Therefore, this study carries on the thorough analysis and discussion. At the same opening degree, with increasing of the particle size, the abrasion of valve frontal surface increases when the size is less than 150 µm and decreases when it is greater than 150 µm. For the valve backflow surface, this boundary value becomes 200 µm. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0264/

Concentration Profiling Of Two Phase Flow In A Gravity Flow Rig Using Optical Tomography

2012 ◽  
Author(s):  
Sallehuddin Ibrahim ◽  
Mohd Fua’ad Rahmat ◽  
Mustafa Musbah Elmajri ◽  
Mohammad Amri Mohammad Yunus
Keyword(s):  
Cross Section ◽  
Two Phase Flow ◽  
Optical Tomography ◽  
Solid Particles ◽  
Gravity Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Tomography System ◽  
Infra Red ◽  
Tomography Method

Matlamat kertas kerja ini ialah untuk membentangkan penyelidikan tentang penggunaan kaedah tomografi optik menggunakan penderia–penderia infra merah untuk pemantauan masa nyata terhadap zarah–zarah pepejal yang dialirkan oleh rig aliran graviti. Penderia terdiri daripada dua projeksi cahaya orthogonal dan dua projeksi cahaya melintang untuk membentuk deretan atas dan bawah menjadi empat projeksi selari. Penumpuan pancaran daripada satu sumber cahaya dan mengalirkannya melalui rejim aliran yang memastikan keamatan pancaran dikesan pada bahagian yang bertentangan disambungkan kepada agihan dan pekali serapan bagi fasa–fasa yang berbeza dalam laluan pancaran. Maklumat pada aliran yang diperolehi oleh penderia-penderia yang dipasang di bahagian atas dan bawah akan dijadikan dalam bentuk digital oleh sistem perolehan data sebelum ia dihantar ke sebuah computer untuk dianalisis untuk memaparkan keratan silang imej. Penyelidikan ini berjaya dikembangkan dan diuji menggunakan sebuah sistem tomografi infra merah untuk memaparkan kepekatan aliran dwi fasa dalam rig aliran gravity. Kata kunci: Profil kepekatan; aliran dwi fasa; tomografi optic; infra-merah; aliran pepejal The objective of this paper is to present research on the use of an optical tomography method using infra–red sensors for real–time monitoring of solid particles conveyed by a gravity flow rig. The sensor comprised two orthogonal and two diagonal light projections to form upstream and downstream arrays in a total of four parallel projections. Collimating the radiated beam from a light source and passing it through a flow regime ensures that the intensity of radiation detected on the opposite side is linked to the distribution and the absorption coefficients of the different phases in the path of the beam. The information on the flow captured using upstream and downstream infra-red sensors is digitized by the DAS system before it was passed into a computer to be analyzed in order to reconstruct the cross section image. This investigation successfully developed and tested an infra–red tomography system to profile the concentration of two phase flow in a gravity flow rig. Key words: Concentration profiles; two phase flow; optical tomography; infra–red; solid flow

scholarly journals A Study on the Acceleration of solid Particles in Solid-Gas Two Phase Flow

1977 ◽  
Vol 14 (2) ◽  
pp. 75-82
Author(s):  
Takeshi KANO ◽  
Sachihiro HIRONO ◽  
Jun-ichi YODOTANI ◽  
Susumu NAKAZAWA ◽  
Hiroshi MAEJIMA
Keyword(s):  
Two Phase Flow ◽  
Solid Particles ◽  
Phase Flow ◽  
Two Phase

scholarly journals Investigation on the Gas–Solid Two-Phase Flow in the Interaction between Plane Shock Wave and Quartz Sand Particles

2020 ◽  
Vol 10 (24) ◽  
pp. 8859
Author(s):  
Xu Peng ◽  
Guoning Rao ◽  
Bin Li ◽  
Shunyao Wang ◽  
Wanghua Chen
Keyword(s):  
Shock Wave ◽  
Quartz Sand ◽  
Two Phase Flow ◽  
Interaction Process ◽  
Solid Particles ◽  
Plane Shock ◽  
Phase Flow ◽  
Momentum Exchange ◽  
Two Phase ◽  
Sand Particles

The interaction between a shock wave and solid particles involves complex gas–solid two-phase flow, which is widely used in industrial processes. Theoretical analysis, an experimental test, and simulation were combined to investigate the interaction process between a shock wave and quartz sand particles. The variation of physical parameters of the two phases during the interaction process was considered theoretically. Then, a novel vertical shock tube generator was employed to record the pressure attenuation and dispersion process of solid particles. Finally, the complex gas–solid two-phase flow was simulated based on the computational fluid dynamics method. The results showed that a nonequilibrium state was formed during the interaction process and momentum exchange generated, resulting in a drag force of the shock wave on the particles. The shock intensity obviously attenuated after the shock wave passed through the solid particles, and this part of the energy was work on the solid particles to drive their dispersion. A three-dimensional annular vortex was generated around the solid particles due to the entrainment effect of airflow. Under the shock wave action of 1.47 Ma, the three types of solid particles with average diameters of 2.5, 0.95, and 0.42 mm presented different motion laws. The particles with smaller size were easier to disperse, and the cloud that formed was larger and more uniform.

Turbulent Solid-Liquid Two-Phase Flow Simulation With Turbulence Intensity and Time Scale Model

2009 ◽  
Author(s):  
Z. Mansoori ◽  
M. Saffar-Avval ◽  
B. Nojabaii ◽  
F. Behzad ◽  
G. Ahmadi
Keyword(s):  
Time Scale ◽  
Model Comparison ◽  
Two Phase Flow ◽  
Solid Phase ◽  
Solid Particles ◽  
Scale Model ◽  
Particle Collision ◽  
Phase Flow ◽  
Two Phase ◽  
Solid Liquid

Two-dimensional simulation of turbulent solid-liquid flow is carried out. The modeling is established for a two-phase flow of solid particles in a vertical pipe water flow. Governing equations of flow and turbulence field are solved in an Eulerian-Lagrangian approach by the use of k-τ (turbulence time scale) model and trajectories of the particles are obtained using the Lagrangian method with a deterministic inter-particle collision model. Comparison between the results of the model for mean and r.m.s velocities of the liquid and solid phase with the experimental results shows a good agreement. The effect of variation of particle density and concentration are studied.

scholarly journals Numerical Simulation of Fine Particle Solid-Liquid Two-Phase Flow in a Centrifugal Pump

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Yanping Wang ◽  
Bozhou Chen ◽  
Ye Zhou ◽  
Jianfeng Ma ◽  
Xinglin Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Internal Pressure ◽  
Centrifugal Pump ◽  
Fine Particle ◽  
Volume Concentration ◽  
Two Phase Flow ◽  
Solid Particles ◽  
Phase Flow ◽  
Two Phase ◽  
Solid Liquid

To study the effect of fine particle size and volume concentration on the performance of solid-liquid two-phase centrifugal pump, the mixture multiphase flow model, RNG k-ε turbulence model, and SIMPLEC algorithm were used to simulate the two-phase flow of the centrifugal pump. The effects of particle size and volume concentration on internal pressure distribution, solid volume distribution, and external characteristics were analyzed. The results show that under the design discharge conditions, with the increase of particle size and volume concentration, the internal pressure of the flow field will decrease, and the volume fraction of solid phase in the impeller passage will also decrease as a whole. The solid particles gradually migrate from the suction surface to the pressure surface, and the particles in the volute channel are mainly concentrated in the flow channel near the outlet side of the volute. With the increase of particle size and volume concentration, the negative pressure value at the inlet of centrifugal pump increases, the total pressure difference at the inlet and outlet decreases, and the head and efficiency decrease accordingly.

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