scholarly journals Numerical Investigation of Erosion Wear in the Hydraulic Amplifier of the Deflector Jet Servo Valve

2020 ◽  
Vol 10 (4) ◽  
pp. 1299
Author(s):  
Hao Yan ◽  
Jing Li ◽  
Cunkun Cai ◽  
Yukai Ren
Keyword(s):  
Cfd Simulation ◽  
Solid Particles ◽  
Contamination Level ◽  
Erosion Wear ◽  
Prediction Formula ◽  
Working Mechanism ◽  
Hydraulic Oil ◽  
Erosion Rates ◽  
Four Levels ◽  
Deflector Jet

Although possessing a remarkable anti-contamination capacity, the deflector jet valve is still confronted with erosion wear brought by solid particles in hydraulic oil. To describe the erosion wear mechanism in the hydraulic amplifier of servo valves, a RANS-based CFD simulation is conducted to obtain its internal wear distribution following the Oka erosion model, which shows the erosion wear in servo valves can be divided into four levels and the major wear happens on the shunt wedge, characterized by a regular and fluctuant distribution. Further, there exist multiple relative maximums of erosion rates, whose locations deviate from the jet center. On this basis, the correlation between the contamination level of hydraulic oil and the degree of erosion wear is established. Moreover, according to the working mechanism of the hydraulic amplifier, a new failure criterion of the deflector jet valve is proposed to carry out valve lifespan analyses. Then, a lifespan prediction formula is obtained, and calculations show that hydraulic oil must have a contamination level superior to NAS 5 if a lifespan of over 20,000 h is expected.

Simulation on mechanism of contamination mitigation through Higee and hydrocyclone techniques in fluid power system

2016 ◽  
Vol 232 (1) ◽  
pp. 77-93
Author(s):  
Ji Hui ◽  
Nie Song-Lin ◽  
Bai Xiao-Rong
Keyword(s):  
Power Systems ◽  
Packed Bed ◽  
Solid Particles ◽  
Fluid Power ◽  
Contamination Level ◽  
Discrete Phase Model ◽  
Hydraulic Oil ◽  
Rotating Packed Bed ◽  
Oil Purification ◽  
Fluid Power Systems

In this study, an innovative Higee hydraulic oil purification device capable of removing the solid particle contaminants and water moisture simultaneously is developed for dealing with the contamination control problem of fluid power systems. The purification device is considered as a combination of two units (hydrocyclone separator and rotating packed bed) according to different separation functions. The mathematical models about the migration regularity and dynamic behavior of different phases have been established, in which discrete phase model model is employed to simulate the solid particles – hydraulic oil separation, and Eulerian model is selected as the multiphase simulation model to simulate the hydraulic oil – water moisture separation. Simulation results demonstrate that the hydrocyclone separator can remove solid particles of 5 to 15 µm, while the rotating packed bed can mitigate water moisture. The results indicate that the developed Higee hydraulic oil purification device can provide an effective and efficient manner for controlling the contamination level of fluid power systems.

Using computational fluid dynamics to predict the erosion rates on the cyclones wall for coal boiler plant

2020 ◽  
Vol 14 (4) ◽  
pp. 7498-7506
Author(s):  
B. Anindito ◽  
T. Nurtono ◽  
S. Winardi
Keyword(s):  
Erosion Rate ◽  
Cfd Simulation ◽  
Swirling Flow ◽  
Local Area ◽  
Reynolds Stress Model ◽  
Solid Particles ◽  
Maintenance Cost ◽  
Inlet Velocity ◽  
Erosion Rates ◽  
Coal Boiler

In the industrial coal boiler, cyclone is used to separate the silica sands (as fluidizing medium) from the furnace combution gas. A gas-solid separation system with turbulent swirling flow that occurs in the cyclone will cause erosion on the cyclone wall. The erosion will cause a decrease in the cyclone performance and increase the maintenance cost. CFD simulation was conducted to predict this erosion using industrial cyclone in the coal boiler industry on its actual dimensions. The dimensions were 5120 mm in diameter and 13970 mm in height. It was performed using the Reynolds Stress Model (RSM) for turbulence flow in the gas phase and the Oka erosion model. The erosion rate on the cyclone wall was investigated at various gas inlet velocity and solid rate. The inlet velocities ranged from 6 to 8 m/s and the solid rates ranged from 30 to 40 kg/s with silica sands as solid particles (0.075 and 1.5 mm in diameter). At the selected local area, the results showed that the higher gas inlet velocity for the same solid rate would increase the erosion rate (about 25%). However, the higher solid rate for the same velocity will also increase the erosion rate on the cyclone wall (about 18%). These results indicate that cyclone wall errosion are significantly affected by inlet gas velocity.

Erosion Mechanism and Sensitivity Parameter Analysis of Natural Gas Curved Pipeline

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Jie Zhang ◽  
Hao Yi ◽  
Zhuo Huang ◽  
Jiadai Du
Keyword(s):  
Natural Gas ◽  
Wear Rate ◽  
Shape Factor ◽  
Great Influence ◽  
Solid Particles ◽  
Parameter Analysis ◽  
Particle Collision ◽  
Erosion Wear ◽  
Gas Wells ◽  
The Impact

With the deepening of natural gas exploitation, the problem of sand production in gas wells is becoming more and more serious, especially in high-yield gas wells. The solid particles in natural gas are very likely to cause erosion and wear of downstream pipelines and throttling manifolds, which makes the pipeline ineffective. Once the pipeline is damaged, the natural gas leaks, which may cause serious catastrophic accidents. In this paper, the impact of sand particles on the pipeline wall is predicted by the analysis of the research on bent and continuous pipeline combined with particle collision model. The parameters of different particles (particle shape factor, particle velocity, and particle diameter), different bent parameters (angle, diameter, and curvature-to-diameter ratio), and the influence of different continuous pipeline parameters (assembly spacing and angle) are explored on the erosion and wear mechanism of curved pipeline. The results show that the shape of the particles has a great influence on the wear of the curved pipeline. As the shape factor of the particles decreases, the wear tends to decrease. The bent area is subject to erosion changes as the particle parameters and piping parameters. The increase in pipeline diameter is beneficial to reduce the maximum and the average erosion wear rate. When the bent angle of the pipeline is less than 90 deg, the maximum erosion wear rate is basically the same. But when it is greater than 90 deg, it decreases with the increase in the bent angle. When the assembly angle of double curved pipeline is between 0 deg and 60 deg, the elbow is subject to severe erosion wear. At the same time, increasing the assembly spacing is beneficial to reduce the erosion wear rate. The research can provide a theoretical support for subsequent engineering applications.

scholarly journals Experimental and Numerical Analysis on Two-Phase Induced Low-Speed Pre-Ignition

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5063
Author(s):  
Norbert Zöbinger ◽  
Thorsten Schweizer ◽  
Thomas Lauer ◽  
Heiko Kubach ◽  
Thomas Koch
Keyword(s):  
Gas Phase ◽  
Cfd Simulation ◽  
Particle Temperature ◽  
Solid Particles ◽  
Two Phase ◽  
Engine Operation ◽  
Oil Droplet ◽  
Low Speed ◽  
Detailed Reaction Mechanism ◽  
Oil Fuel

The root cause of the initial low-speed pre-ignition (LSPI) is not yet clarified. The literature data suggest that a two-phase phenomenon is most likely triggering the unpredictable premature ignitions in highly boosted spark-ignition engines. However, there are different hypotheses regarding the actual initiator, whether it is a detached liquid oil-fuel droplet or a solid-like particle from deposits. Therefore, the present work investigates the possibility of oil droplet-induced pre-ignitions using a modern downsized engine with minimally invasive endoscopic optical accessibility incorporating in-cylinder lubrication oil detection via light-induced fluorescence. This setup enables the differentiation between liquid and solid particles. Furthermore, the potential of hot solid particles to initiate an ignition under engine-relevant conditions is analyzed numerically. To do so, the particle is generalized as a hot surface transferring heat to the reactive ambient gas phase. The gas-phase reactivity is represented as a TRF/air mixture based on RON/MON specifications of the investigated fuel. The chemical processes are predicted using a semi-detailed reaction mechanism, including 137 species and 633 reactions in a 2D CFD simulation framework. In the optical experiments, no evidence of a liquid oil droplet-induced pre-ignition could be found. Nevertheless, all observed pre-ignitions had a history of flying light-emitting objects. There are strong hints towards solid-like deposit LSPI initiation. The application of the numerical methodology to mean in-cylinder conditions of an LSPI prone engine operation point reveals that particles below 1000 K are not able to initiate a pre-ignition. A sensitivity analysis of the thermodynamic boundary conditions showed that the particle temperature is the most decisive parameter on the calculated ignition delay time.

scholarly journals The alteration of the operating parameteres of the aerocyclone depending on the geometry of the vortex finder

2021 ◽  
Vol 11 (5) ◽  
pp. 180-187
Author(s):  
Blanka Orosz ◽  
Máté Petrik ◽  
L. Gábor Szepesi
Keyword(s):  
Production Process ◽  
Significant Role ◽  
Cfd Simulation ◽  
Solid Particles ◽  
Engineering Practice ◽  
Operating Parameters ◽  
Hazardous Material ◽  
Vortex Finder

The engineering practice in general requires the ability to recognize the possible hazards associated with the coordinated production process. Solid particles found in the air can potentially be one of these, therefore it is fundamental to deal with the risk posed by certain types of dusts. An industrial cyclone is an equipment which is designed to separate the hazardous material from the harmless matter within the air. First and foremost the efficiency of a cyclone is determined substantially by the operating parameters. Certain geometries of the device however, such as the vortex finder can also have a significant role. The experiment conducted revolves around a CFD simulation to determine the efficiency of the apparatus based on different geometries in general and also regarding the vortex finder. The results indicate that the length of the vortex detector has a more significant effect, than the overall geometry.

scholarly journals Detection of Gas-Solid Two-Phase Flow Based on CFD and Capacitance Method

2018 ◽  
Vol 8 (8) ◽  
pp. 1367 ◽  
Author(s):  
Wanting Zhou ◽  
Yue Jiang ◽  
Shi Liu ◽  
Qing Zhao ◽  
Teng Long ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Cfd Simulation ◽  
Fluid Model ◽  
Flow Direction ◽  
Solid Particles ◽  
Drilling Process ◽  
Sources Of Information ◽  
Discrete Phase Model ◽  
Horizontal Drilling ◽  
Annular Channels

Multiphase flow in annular channels is complex, particularly in the region where the flow direction abruptly changes between the inner pipe and the outer pipe, as the cases in horizontal drilling and pneumatic conveying. Simplified models and experience are still the main sources of information. First, to understand the process more deeply, Computational Fluid Dynamics (CFD) package Fluent is used to simulate the gas-solid flow in the horizontal and the inclined section of an annular pipe. Discrete Phase Model (DPM) is adopted to calculate the trajectories of solid particles of different sizes at different air velocities. Also, the Two-Fluid model is used to simulate the sand flow in the inclined section for the case of air flow stoppage, for which an experiment is also conducted to verify the CFD simulation. Simulation results reveal the behaviour of the solid particles showing the dispersed spatial distribution of small particles near the entrance. On the other hand, larger particles manifest a distinct sedimented flow pattern along the bottom of the pipe. The density distribution of the particles over a pipe cross section is demonstrated at a variety of air velocities. The results also show that the large airspeed tends to generate swirls near the outlet of the inner pipe. In addition, Electrical Capacitance Tomography (ECT) technology is used to reconstruct the spatial distribution of particles, and the cross-correlation algorithm to detect velocity. Both the distribution and the velocity measurement by electric sensors agree reasonably well with the CFD predictions. The details revealed by CFD simulation and the mutual-verification between CFD simulation and the ECT method of this study could be valuable for the industry in drilling process control and equipment development.

Study on role of particle shape in erosion wear of austenitic steel using image processing analysis technique

2018 ◽  
Vol 233 (5) ◽  
pp. 712-725 ◽  
Author(s):  
Jashanpreet Singh ◽  
Satish Kumar ◽  
SK Mohapatra
Keyword(s):  
Fly Ash ◽  
Austenitic Steel ◽  
Bottom Ash ◽  
Three Dimensional ◽  
Underlying Mechanism ◽  
Solid Particles ◽  
Erosion Wear ◽  
Sand Surface ◽  
Tailings Sand ◽  
Slurry Pot Tester

Properties of flowing media (e.g. such as fly ash, bottom ash, coal, mineral tailings, sand slurries, etc.) play a crucial role in the service life of centrifugal slurry pump components. Generally, these solid particles vary in shape and size. In literature, a limited number of studies have been carried out to investigate the influence of particle size and shape on erosion wear. Stainless steel (SS 316L) is the most commonly used material for the fabrication of slurry pump components namely, casing, impeller, shafts, and sealing columns. In the present study, the influence of particle type and circularity factor on erosion wear of austenitic steel has been studied. A slurry pot tester (Ducom TR-41) was used to perform the experiments that established the erosion wear of slurry pump austenitic steel under the influence of the parameters noted above. Abrasives used in the current study are fly ash, bottom ash, and sand. Surface smoothness, circularity factor, coefficient of variance, sphericity, and solidity of solid particles were also analyzed prior to performing the experiments. The circularity factor value and erosion wear rate hold a power law relationship. Three-dimensional surface plots were plotted to explain the underlying mechanism of erosion wear.

Erosion Wear Behavior of Coatings with Growth Defects Produced by Ion Beam Enhanced Pulsed Filtered Vacuum Arc Deposition

2010 ◽  
Vol 97-101 ◽  
pp. 1527-1531 ◽  
Author(s):  
Feng Fang Wu ◽  
Jian Xin Deng ◽  
Pei Yan ◽  
Wen Long Song
Keyword(s):  
Erosion Rate ◽  
Wear Behavior ◽  
Ion Beam ◽  
Hard Metal ◽  
Solid Particles ◽  
Wear Loss ◽  
Erosion Wear ◽  
Growth Defects ◽  
Tin Coatings ◽  
Arc Deposition

The erosion wear behavior of TiN coatings with growth defects was studied. The TiN coatings were produced on a hard metal by ion beam enhanced pulsed filtered vacuum cathode arc deposition. The erosion wear was tested with a gas blast apparatus. In the test, TiN coatings were impacted at an impingement angle of 90° by angular SiC solid particles with an average diameter of 124um. The maximum depth of the erosion scar measured by the optical profiler was used to evaluate the erosion wear loss of the coatings. The coatings proved to have much lower erosion rate than that of the substrate material and consequently, the erosion rate increased significantly to the high level of the hard metal substrate after the coatings were penetrated. The failure mechanism was revealed by examining the surface morphologies of the coatings before and after the erosion test. The erosive wear of the TiN coatings with growth defects behaved as typical brittle materials. The damage mechanism of the coatings with growth defects was described.

CFD Study on must of Grapes Separation in a Hydrocyclone

2013 ◽  
Vol 837 ◽  
pp. 645-650
Author(s):  
Petru Cârlescu ◽  
Ioan Tenu ◽  
Marius Baetu ◽  
Radu Rosca
Keyword(s):  
Cfd Simulation ◽  
Reynolds Stress Model ◽  
Continuous Phase ◽  
Solid Particles ◽  
Advanced Degree ◽  
Separation And Purification ◽  
Discrete Phase Model ◽  
Flow Rates ◽  
Discrete Phase ◽  
Simulation And Experiment

Abstract. Hydrocyclones are increasingly used in the food industry for various separation and purification. In this paper, an optimization was made to design a hydrocyclone model using CFD (Computational Fluid Dynamics). CFD simulation is performed with FLUENT software by coupling the Reynolds Stress Model (RSM) for must of grapes flow with Discrete Phase Model (DPM) for solid particles trajectory. Coupling of discrete phase (particles) and continuous phase (must of grapes) in the mathematical model is set so that the continuous phase to influence discrete phase. Tracking particles traiectory in this hydrocyclone allows advanced degree is separation so obtained to the maximum particle size approaching the size of a yeast cell 10 μm, without separating them. Hydrocyclone dimensional designed simulation was performed and analyzed on an experimental pilot plant for three different must flow rates supply. Introduced particle flow rates simulation and experiment does not exceed 10% of the must flow rates. The degree of separation obtained is in agreement with experimental data.

CFD Diagnosis of the Cyclotol Manufacturing Plant: Product Quality and Process Operation

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
Jimmy Lea ◽  
Adesoji A Adesina
Keyword(s):  
Product Quality ◽  
Cfd Simulation ◽  
Rejection Rate ◽  
Current Data ◽  
Solid Particles ◽  
Cfd Modeling ◽  
Velocity Magnitude ◽  
Water Composition ◽  
Process Operation ◽  
Tank Design

The production of cyclotol, a military high explosive used in manufacture of aerial bombs, involves the multiphase mixing of molten TNT, RDX solid particles and water. Textural homogeneity of the final cyclotol mixture and near-zero water composition are critical requirements to minimize bomb-rejection rate and hence improved plant profitability. Although current data reveal significant statistical variation in product quality, detailed investigation of the complex mixing operation does not lend itself to physical experimentation due to the explosive nature of the process. This forestalls opportunities for improved process operation or re-design. To circumvent this constraint, a computational fluid dynamics (CFD) simulation of the industrial-scale process was carried out to understand how current mixing protocols impact on key in-tank profiles such as water draw-down, RDX particles suspension, turbulence kinetic energy, velocity magnitude, vector direction and water-entrainment. The analysis revealed that while the maximum impeller speed allowable to avoid water draw-down is 20 rpm, the minimum speed necessary to suspend the RDX particles for homogeneous mixing is 40 rpm. These opposing requirements are neither accommodated by the present mixing protocols nor achievable with the existing tank design. Even so, the 'mystery' of irrational cyclotol quality has been uncovered by a judicious use of CFD modeling and opened up the possibility of a revised tank design and optimal process operation for superior plant economics.

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