scholarly journals Numerical simulation of atomization and combustion characteristics of high-moisture organic wastewater

2021 ◽  
Vol 245 ◽  
pp. 02042
Author(s):  
Jing Ding ◽  
Qiang Tang ◽  
Tengfei Zhang
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
High Efficiency ◽  
Combustion Process ◽  
Combustion Method ◽  
Spray Angle ◽  
Solid Cone ◽  
Spray Cone ◽  
Cone Model ◽  
Wastewater Samples

The combustion method, due to its convenience and high-efficiency in harmless treatment, has been widely used in disposal of wastewater. With a wastewater burner as the study case, we performed numerical simulation by the Fluent software, analyzed the flowing and combustion process of the wastewater samples in the burner, compared the combustion effect of different atomization conditions — the spray cone model (hollow cone model, solid cone model), the spray angle, non-uniform grain size, uniform grain size. The study aims to provide suggestions for design and selection of wastewater burners.

Synthesis and Characterization of Hexagonal Shaped Nanocrystalline Zinc Oxide Powders

2014 ◽  
pp. 204-217 ◽  
Author(s):  
M. Ahmad ◽  
E. Ahmed ◽  
N. R. Khalid ◽  
M. J. Jackson ◽  
W. Ahmed
Keyword(s):  
Grain Size ◽  
Elevated Temperatures ◽  
Combustion Process ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Wurtzite Phase ◽  
X Ray ◽  
Oxide Powders ◽  
Heat Treated ◽  
Zno Powders

Nanocrystalline ZnO powders are synthesized using a quick, simple and inexpensive combustion method. Glycine and zinc nitrate, used as fuel and oxidant/cation sources respectively, were mixed together at room temperature to form a slurry or gel. A series of experiments were performed to synthesize nanoparticles for different fuel to oxidant ratios. The rate of heating and stirring greatly influenced the combustion process. The as-synthesized powder was heat treated at elevated temperatures for varying time to remove adsorbed impurities from the surface of the ZnO nanoparticles. Both the as-synthesized and heat treated powders were characterized using a variety of analytical techniques. The hexagonal wurtzite phase of the ZnO powder was revealed from x-ray diffraction measurements. A decrease in the x-ray diffraction density (Dx) and the bulk density (D) resulted in an increase in percentage porosity (%P) of as-synthesized and heat treated ZnO powders. The range of fuel to oxidant ratios used in the present work indicates that they had a strong influence on the grain size of ZnO powders. The average grain size estimated by using the Scherer formula indicated an approximate value of 6-21 nm for the as-synthesized and heat treated samples.

Synthesis and Characterization of Hexagonal Shaped Nanocrystalline Zinc Oxide Powders

2012 ◽  
Vol 2 (2) ◽  
pp. 61-76 ◽  
Author(s):  
M. Ahmad ◽  
E. Ahmed ◽  
N. R. Khalid ◽  
M. J. Jackson ◽  
W. Ahmed
Keyword(s):  
Grain Size ◽  
Elevated Temperatures ◽  
Combustion Process ◽  
Combustion Method ◽  
X Ray Diffraction ◽  
Wurtzite Phase ◽  
X Ray ◽  
Heat Treated ◽  
Average Grain Size ◽  
Zno Powders

Nanocrystalline ZnO powders are synthesized using a quick, simple and inexpensive combustion method. Glycine and zinc nitrate, used as fuel and oxidant/cation sources respectively, were mixed together at room temperature to form a slurry or gel. A series of experiments were performed to synthesize nanoparticles for different fuel to oxidant ratios. The rate of heating and stirring greatly influenced the combustion process. The as-synthesized powder was heat treated at elevated temperatures for varying time to remove adsorbed impurities from the surface of the ZnO nanoparticles. Both the as-synthesized and heat treated powders were characterized using a variety of analytical techniques. The hexagonal wurtzite phase of the ZnO powder was revealed from x-ray diffraction measurements. A decrease in the x-ray diffraction density (Dx) and the bulk density (D) resulted in an increase in percentage porosity (%P) of as-synthesized and heat treated ZnO powders. The range of fuel to oxidant ratios used in the present work indicates that they had a strong influence on the grain size of ZnO powders. The average grain size estimated by using the Scherer formula indicated an approximate value of 6-21 nm for the as-synthesized and heat treated samples.

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

scholarly journals Free Stream Behavior of Hydrogen Released from a Fluidic Oscillating Nozzle

Fluids ◽  
2021 ◽  
Vol 6 (7) ◽  
pp. 245
Author(s):  
Anja Fink ◽  
Oliver Nett ◽  
Simon Schmidt ◽  
Oliver Krüger ◽  
Thomas Ebert ◽  
...  
Keyword(s):  
Free Stream ◽  
Combustion Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Vertical Direction ◽  
Spray Angle ◽  
Transport Sector ◽  
Flow Measurements ◽  
Injection Process ◽  
Bottom Dead Center

The H2 internal combustion engine (ICE) is a key technology for complete decarbonization of the transport sector. To match or exceed the power density of conventional combustion engines, H2 direct injection (DI) is essential. Therefore, new injector concepts that meet the requirements of a H2 operation have to be developed. The macroscopic free stream behavior of H2 released from an innovative fluidic oscillating nozzle is investigated and compared with that of a conventional multi-hole nozzle. This work consists of H2 flow measurements and injection tests in a constant volume chamber using the Schlieren method and is accompanied by a LES simulation. The results show that an oscillating H2 free stream has a higher penetration velocity than the individual jets of a multi-hole nozzle. This behavior can be used to inject H2 far into the combustion chamber in the vertical direction while the piston is still near bottom dead center. As soon as the oscillation of the H2 free stream starts, the spray angle increases and therefore H2 is also distributed in the horizontal direction. In this phase of the injection process, spray angles comparable to those of a multi-hole nozzle are achieved. This behavior has a positive effect on H2 homogenization, which is desirable for the combustion process.

scholarly journals Research on the Operating Characteristics of Hydraulic Free-Piston Engines: A Systematic Review and Meta-Analysis

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3530
Author(s):  
Fukang Ma ◽  
Shuanlu Zhang ◽  
Zhenfeng Zhao ◽  
Yifang Wang
Keyword(s):  
Systematic Review ◽  
High Efficiency ◽  
Meta Analysis ◽  
Combustion Process ◽  
Research Progress ◽  
Future Research ◽  
Operating Characteristics ◽  
Piston Engine ◽  
Free Piston ◽  
Free Piston Engine

The hydraulic free-piston engine (HFPE) is a kind of hybrid-powered machine which combines the reciprocating piston-type internal combustion engine and the plunger pump as a whole. In recent years, the HFPE has been investigated by a number of research groups worldwide due to its potential advantages of high efficiency, energy savings, reduced emissions and multi-fuel operation. Therefore, our study aimed to assess the operating characteristics, core questions and research progress of HFPEs via a systematic review and meta-analysis. We included operational control, starting characteristics, misfire characteristics, in-cylinder working processes and operating stability. We conducted the literature search using electronic databases. The research on HFPEs has mainly concentrated on four kinds of free-piston engine, according to piston arrangement form: single piston, dual pistons, opposed pistons and four-cylinder complex configuration. HFPE research in China is mainly conducted in Zhejiang University, Tianjin University, Jilin University and the Beijing Institute of Technology. In addition, in China, research has mainly focused on the in-cylinder combustion process while a piston is free by considering in-cylinder combustion machinery and piston dynamics. Regarding future research, it is very important that we solve the instabilities brought about by chance fluctuations in the combustion process, which will involve the hydraulic system’s efficiency, the cyclical variation, the method of predicting instability and the recovery after instability.

Numerical Simulation of Premixed Propane/Air Flame Propagation Using a Dynamically Thickened Flame Approach

2013 ◽  
Vol 444-445 ◽  
pp. 1574-1578 ◽  
Author(s):  
Hua Hua Xiao ◽  
Zhan Li Mao ◽  
Wei Guang An ◽  
Qing Song Wang ◽  
Jin Hua Sun
Keyword(s):  
Numerical Simulation ◽  
Flame Propagation ◽  
Numerical Study ◽  
Vortex Motion ◽  
Combustion Process ◽  
Single Step ◽  
Premixed Combustion ◽  
Premixed Flame ◽  
Flame Surface ◽  
Arrhenius Kinetics

A numerical study of premixed propane/air flame propagation in a closed duct is presented. A dynamically thickened flame (TF) method is applied to model the premixed combustion. The reaction of propane in air is taken into account using a single-step global Arrhenius kinetics. It is shown that the premixed flame undergoes four stages of dynamics in the propagation. The formation of tulip flame phenomenon is observed. The pressure during the combustion process grows exponentially at the finger-shape flame stage and then slows down until the formation of tulip shape. After tulip formation the pressure increases quickly again with the increase of the flame surface area. The vortex motion behind the flame front advects the flame into tulip shape. The study indicates that the TF model is quite reliable for the investigation of premixed propane/air flame propagation.

Structural Design and Forming Method of Single-Curved Surface Structure Based on Miura-Origami

2016 ◽  
Author(s):  
Hairui Wang ◽  
Chunfang Guo ◽  
Yujie Li ◽  
Yahua Liu ◽  
Minjie Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Structural Design ◽  
High Efficiency ◽  
Circular Tube ◽  
Great Influence ◽  
Curved Surface ◽  
Structural Performance ◽  
Forming Process ◽  
Structural Support ◽  
Vacuum Forming

With the advantage of high adaptability, Miura-origami structure with curvature shows various engineering applications such as a sandwich between two stiff facings with curvature requirements and structural support to form a circular tube. In this research, a forming method of polymer circular tube with single-curved surface origami expressed by five parameters was established and its corresponding theory was solved considering forming rationality in actual manufacturing. The components of circular tube were fabricated by the vacuum forming process and then spliced together. We conducted numerical simulation to analyze the structural performance of the tube with five parameters and shown that these parameters have a great influence on energy absorbed performance. Finally, a male mold of a part with Arc Miura-origami structure was designed and fabricated. The parts with Arc Miura-origami were manufactured using vacuum forming process and then spliced and bonded together into a two-layer tube. This research may provide a method to design and fabricate Miura-origami structure with high efficiency and quality.

Modeling Recrystallization for 3D Multi-Pass Forming Processes

2007 ◽  
Vol 558-559 ◽  
pp. 1201-1206 ◽  
Author(s):  
Mihaela Teodorescu ◽  
Patrice Lasne ◽  
Roland E. Logé
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Present Model ◽  
Static Recrystallization ◽  
Volume Fraction ◽  
The Other ◽  
Finite Element Code ◽  
3D Numerical Simulation ◽  
Fraction Distribution ◽  
Simulation Results

The present work concerns the simulation of metallurgical evolutions in 3D multi-pass forming processes. In this context, the analyzed problem is twofold. One point refers to the management of the microstructure evolution during each pass or each inter-pass period and the other point concerns the management of the multi-pass aspects (different grain categories, data structure). In this framework, a model is developed and deals with both aspects. The model considers the microstructure as a composite made of a given (discretized) number of phases which have their own specific properties. The grain size distribution and the recrystallized volume fraction distribution of the different phases evolve continuously during a pass or inter-pass period. With this approach it is possible to deal with the heterogeneity of the microstructure and its evolution in multi-pass conditions. Both dynamic and static recrystallization phenomena are taken into account, with typical Avrami-type equations. The present model is implemented in the Finite Element code FORGE2005®. 3D numerical simulation results for a multi-pass process are presented.

Modeling and Numerical Simulation Research on Hollow Steel Ingot Forging Process of Heavy Cylinder Forging

2013 ◽  
Vol 712-715 ◽  
pp. 627-632
Author(s):  
Min Liu ◽  
Qing Xian Ma
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Shear Zone ◽  
Grain Refinement ◽  
Steel Ingot ◽  
Effective Strain ◽  
Meridian Plane ◽  
Forging Process ◽  
Forming Load ◽  
Average Grain Size

Aiming at the disadvantages of low utilization ratio of steel ingot, uneven microstructure properties and long production period in the solid steel ingot forging process of heavy cylinder forgings such as reactor pressure vessel, a new shortened process using hollow steel ingot was proposed. By means of modeling of lead sample and DEFORM-3D numerical simulation, the deformation law and grain refinement behavior for 162 ton hollow steel ingot upsetting at different reduction ratios, pressing speeds and friction factors were investigated, and the formation rule of inner-wall defects in upsetting of hollow steel ingots with different shape factors was further analyzed. Simulation results show that the severest deformation occurs in the shear zone of meridian plane in the upsetting process of hollow steel ingot, and the average grain size in the shear zone is the smallest. As pressing speed increases, the forming load gradually increases and the deformation uniformity gets worse, while the average grain size decreases. An increase in friction factor can increase the peak value of effective strain, but it significantly reduces the deformation uniformity, increases the forming load and goes against grain refinement. Moreover, the four kinds of defects on the inner wall of steel ingot can be eliminated effectively by referring to the plotted defect control curve for hollow steel ingot during high temperature upsetting.

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