scholarly journals Research on Multiphysics Coupling Fields in Electrochemical Trepanning of Lateral Flow

2021 ◽  
Author(s):  
Gaopan Lei ◽  
Dong Zhu ◽  
Di Zhu
Keyword(s):  
Flow Field ◽  
Surface Quality ◽  
Current Density ◽  
Volume Fraction ◽  
Flow Path ◽  
Lateral Flow ◽  
Flow Mode ◽  
Forward Flow ◽  
Electrolyte Conductivity ◽  
Multiphysics Coupling

Abstract Electrochemical trepanning (ECTr) is an effective method for machining the ruled surface parts. Generally, the forward flow mode is used in ECTr. Under the forward flow, the streamlines at the outlet are divergent, resulting in the obvious flow patterns at the outlet and the instability of the machining process. In ECTr of a diffuser with a special structure, the lateral flow mode is adopted to improve the uniformity of the flow field, thereby improving the surface quality at the hub. ECTr is a complicated multiphysics coupling process. To investigate the distributions of electric field, two-phase flow field and thermal field in ECTr with lateral flow, a multiphysics coupling field model was established. In this model, a coupling relationship was formed between the various physical fields through the change of the electrolyte conductivity. Through the multiphysics coupling simulation, the changes of the gas bubbles volume fraction, the electrolyte temperature, the electrolyte conductivity and the current density were obtained along the flow path. Compared with the inlet of the electrolyte, the gas bubbles volume fraction and the temperature at the outlet increased by 38.8% and 6.3 K, respectively. Under the combined influence, the conductivity decreased by 7.227 S/m at the outlet, resulting in a decrease of 57.81 A/cm2 in the current density. Then, the corresponding experiment of lateral flow ECTr was performed to verify the simulation results. Along the flow path, the thickness of the machined blade gradually increased, varying from 2.09 mm to 2.76 mm. The surface quality gradually deteriorated along the flow path and the surface roughness varied from Ra 0.72 μm to Ra 1.05 μm. Combining the simulation and the experiment, the correctness and the effectiveness of the multiphysics coupling model and simulation were confirmed. The results can be applied to other ECM processes.

scholarly journals Face Grinding Surface Quality of High Volume Fraction SiCp/Al Composite Materials

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Xu Zhao ◽  
Yadong Gong ◽  
Guiqiang Liang ◽  
Ming Cai ◽  
Bing Han
Keyword(s):  
Friction Coefficient ◽  
Surface Morphology ◽  
Surface Quality ◽  
Volume Fraction ◽  
High Volume ◽  
Spindle Speed ◽  
High Volume Fraction ◽  
Machining Parameters ◽  
Al Composite

AbstractThe existing research on SiCp/Al composite machining mainly focuses on the machining parameters or surface morphology. However, the surface quality of SiCp/Al composites with a high volume fraction has not been extensively studied. In this study, 32 SiCp/Al specimens with a high volume fraction were prepared and their machining parameters measured. The surface quality of the specimens was then tested and the effect of the grinding parameters on the surface quality was analyzed. The grinding quality of the composite specimens was comprehensively analyzed taking the grinding force, friction coefficient, and roughness parameters as the evaluation standards. The best grinding parameters were obtained by analyzing the surface morphology. The results show that, a higher spindle speed should be chosen to obtain a better surface quality. The final surface quality is related to the friction coefficient, surface roughness, and fragmentation degree as well as the quantity and distribution of the defects. Lower feeding amount, lower grinding depth and appropriately higher spindle speed should be chosen to obtain better surface quality. Lower feeding amount, higher grinding depth and spindle speed should be chosen to balance grind efficiently and surface quality. This study proposes a systematic evaluation method, which can be used to guide the machining of SiCp/Al composites with a high volume fraction.

Synthesis of high-temperature thermally expandable microcapsules and their effects on foaming quality and surface quality of foamed ABS materials

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 519-527
Author(s):  
Wei Gong ◽  
Xianglin Pei ◽  
Xiaogang Yin ◽  
Daming Ban ◽  
Hai Fu ◽  
...  
Keyword(s):  
High Temperature ◽  
Surface Quality ◽  
Volume Fraction ◽  
Crosslinking Agent ◽  
Acrylonitrile Butadiene Styrene ◽  
Foaming Agent ◽  
Blowing Agent ◽  
Good Surface ◽  
Butadiene Styrene

AbstractIn this paper, acrylonitrile and hydroxypropyl acrylate are used as the binary polymerization monomers, and isooctane is used as the foaming agent to prepare high-temperature thermally expandable microcapsules. Analysis of the effect of blowing agent and crosslinking agent on the expansion properties of high-temperature thermally expandable microcapsules, the effects of foaming agent azodicarbonamide (ADCA) and micro-expansion capsule on the surface quality and foaming quality of foamed acrylonitrile–butadiene–styrene (ABS) products were investigated. The foamed product prepared by the high-temperature microcapsule has a good surface quality, the gloss is 52.3, the cell is not easily deformed, and the volume fraction is 4%; the foamed ABS/ADCA material has poor cell uniformity, the cell is easily deformed, the volume fraction is 6.5%, the surface quality is poor, and the gloss is only 8.7.

Sol-Gel Derived Titania/Hydroxyapatite Layer on Titanium Substrate

2011 ◽  
Vol 117-119 ◽  
pp. 332-334 ◽  
Author(s):  
Wen Yan Wang ◽  
Yu Wu ◽  
Jing Pei Xie ◽  
Gao Lu ◽  
Xiao Ming Dong ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Surface Quality ◽  
Phase Formation ◽  
Volume Fraction ◽  
Sol Gel ◽  
Calcium Nitrate ◽  
Titanium Substrate ◽  
Gel Method ◽  
Good Surface ◽  
Coating Method

In this study, calcium nitrate(Ca(NO3)2•4H2O) and phosphorus pentoxide(P2O5) were used as precursor to prepare hydroxyapatite(HA) layer by sol-gel method, followed by a dipping-coating method to coat HA layer onto Ti. Phase formation and microstructure were investigated by XRD and SEM to study the influence of atmosphere on the property of HA layer. The results revealed that there exists no large cracks in the layer which was heated in the nitrogen, leading to a good surface quality compared with the layer which was heated in the air. And there is no obvious difference in crystallinity and volume fraction of HA in the layer when adopting heat treatment in different atmospheres.

An Experimental Investigation of the Effects of the Environmental Conditions and the Channel Depth for an Air-Breathing Polymer Electrolyte Membrane Fuel Cell

2008 ◽  
Vol 5 (4) ◽  
Author(s):  
Yong Hun Park ◽  
Jerald A. Caton
Keyword(s):  
Fuel Cell ◽  
Relative Humidity ◽  
Flow Field ◽  
Current Density ◽  
Environmental Conditions ◽  
Polymer Electrolyte Membrane ◽  
Channel Depth ◽  
Air Breathing ◽  
Fuel Cell Performance ◽  
Electrolyte Membrane

The effects of the environmental conditions and the channel depth for an air-breathing polymer electrolyte membrane fuel cell were investigated experimentally. The fuel cell used in this work included a membrane and electrode assembly, which possessed an active area of 25 cm2 with Nafion® 117 membrane. Triple serpentine designs for the flow fields with two different flow depths were used in this research. The experimental results indicated that the relative humidity and temperature play an important role with respect to fuel cell performance. The fuel cell needs to be operated at least 20 min to obtain stable performance. When the shallow flow field was used, the performance increased dramatically for low humidity and slightly for high humidity. The current density was obtained around only 120 mA/cm2 at 30°C with an 80% relative humidity, which was nearly double the performance for the deep flow field. The minimum operating temperature for an air-breathing fuel cell would be 20°C. When it was 10°C at 60% relative humidity, the open circuit voltage dropped to around 0.65 V. The fuel cell performance improved with increasing relative humidity from 80% to 100% at high current density.

Time-Averaged and Time-Accurate Aerodynamic Effects of Forward Rotor Cavity Purge Flow for a High-Pressure Turbine: Part I—Analytical and Experimental Comparisons

2012 ◽  
Author(s):  
Brian R. Green ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Flow Path ◽  
Field Analysis ◽  
High Pressure Turbine ◽  
Purge Flow

The effect of rotor purge flow on the unsteady aerodynamics of a high-pressure turbine stage operating at design corrected conditions has been investigated both experimentally and computationally. The experimental configuration consisted of a single-stage high-pressure turbine with a modern film-cooling configuration on the vane airfoil as well as the inner and outer end-wall surfaces. Purge flow was introduced into the cavity located between the high-pressure vane and the high-pressure disk. The high-pressure blades and the downstream low-pressure turbine nozzle row were not cooled. All hardware featured an aerodynamic design typical of a commercial high-pressure ratio turbine, and the flow path geometry was representative of the actual engine hardware. In addition to instrumentation in the main flow path, the stationary and rotating seals of the purge flow cavity were instrumented with high frequency response, flush-mounted pressure transducers and miniature thermocouples to measure flow field parameters above and below the angel wing. Predictions of the time-dependent flow field in the turbine flow path were obtained using FINE/Turbo, a three-dimensional, Reynolds-Averaged Navier-Stokes CFD code that had the capability to perform both steady and unsteady analysis. The steady and unsteady flow fields throughout the turbine were predicted using a three blade-row computational model that incorporated the purge flow cavity between the high-pressure vane and disk. The predictions were performed in an effort to mimic the design process with no adjustment of boundary conditions to better match the experimental data. The time-accurate predictions were generated using the harmonic method. Part I of this paper concentrates on the comparison of the time-averaged and time-accurate predictions with measurements in and around the purge flow cavity. The degree of agreement between the measured and predicted parameters is described in detail, providing confidence in the predictions for flow field analysis that will be provided in Part II.

Study of an Innovative Versatile Flow Design Suitable for Fuel Cells

2017 ◽  
Vol 14 (4) ◽  
Author(s):  
S. Meenakshi ◽  
Prakash C. Ghosh
Keyword(s):  
Fuel Cells ◽  
Flow Field ◽  
Flow Distribution ◽  
Polymer Electrolyte Fuel Cell ◽  
Cathode Side ◽  
Flow Mode ◽  
Hybrid Mode ◽  
Large Area ◽  
Dead End ◽  
A Current

Flow field plays an important role in the performances of the fuel cells, especially in large area fuel cells. In the present work, an innovative, versatile flow field, capable of combining in different conventional modes is reported and evaluated in a polymer electrolyte fuel cell (PEFC) with an active area of 150 cm2. The proposed design is capable of offering serpentine, interdigitated, counterflow, dead-end, and serpentine-interdigitated hybrid mode. Moreover, it is possible to switch over from one flow mode to another mode of flow during operation at any point of time. The flow design consists of the multichannel parallel serpentine flow (SP) field and a pair of an inlet and outlet manifolds instead of conventional single inlet and outlet manifold. Flow distribution was successfully altered without affecting the performances, and it was observed a combination of serpentine and interdigitated on the cathode side offered steady performance for more than 20 min when it was operated at a current density of 700 mA cm−2.

STABILIZATION OF Bi(2223) SUPERCONDUCTING PHASE BY VANADIUM OXIDE ADDITION

1993 ◽  
Vol 07 (01n03) ◽  
pp. 157-161 ◽  
Author(s):  
D. SURESH BABU ◽  
G. NARSING RAO ◽  
L. BROHAN ◽  
M. GANNE
Keyword(s):  
Critical Current Density ◽  
Current Density ◽  
Flux Pinning ◽  
Volume Fraction ◽  
Ac Susceptibility ◽  
Superconducting Phase ◽  
Nominal Composition ◽  
Oxide Addition ◽  
Probable Role

We report on the ac susceptibility, microwave absorption and dc magnetization of Bi 2− x V x Sr 2 Ca 2 Cu 3 O y (nominal composition). The low T c (2212) phase ( T c = 85 K ) dominates in the x = 0 sample with extremly weak flux pinning. In x = 0.4 sample, both flux pinning and volume fraction of the high T c (2223) phase ( T c = 105 K ) were increased. The intragrain critical current density of the sample with x = 0.4 was estimated and found to be comparable with that of Pb doped Bi 2 Sr 2 Ca 2 Cu 3 O y superconductor. The data suggest that addition of V 2 O 5 in Bi 2 Sr 2 Ca 2 Cu 3 O y system increases the volume fraction of the high T c phase. Probable role of vanadium in enhancing the high T c (2223) phase in Bi-V-Sr-Ca-Cu-O system is discussed.

CFD simulation of air effect on flow field characteristics of hydro-viscous clutch with constant speed difference

2018 ◽  
Vol 19 (2) ◽  
pp. 208
Author(s):  
Xudong Zheng ◽  
Fangwei Xie ◽  
Diancheng Wu ◽  
Xinjian Guo ◽  
Bing Zhang ◽  
...  
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Power Transmission ◽  
Volume Fraction ◽  
Phase Distribution ◽  
Constant Speed ◽  
Distribution Law ◽  
Two Phase ◽  
Oil Film ◽  
Speed Difference

The purpose of this paper is to study the air effects on transmission characteristics of hydro-viscous clutch and reveal the distribution law of the flow field of the oil film. The computational-fluid-dynamics (CFD) simulation model of oil film with radial oil grooves between friction pairs is taken as the study object. Considering the air effects, the pressure field, two-phase distribution, transmission torque and temperature field of the oil film are analyzed comparatively by using the CFD technology. The results show that the presence of air changes the pressure and temperature distributions of the oil film. With increase of the absolute rotational speed, the air volume fraction increases and the radius value of the air-liquid boundary decreases under condition of constant speed difference, which makes the coverage rate of the oil film on the surface of the friction disks reduce and the transmission torque of the oil film decrease. These simulation results are attributed to the study of hydro-viscous-drive and its applications. This paper also can provide a theoretical basis for the mechanism of power transmission through oil film in the presence of air effects.

Simulation of Indoor Air Flow Fields in Buildings With Large Interior Spaces With Stratified Air Conditioning and Perforated Side Wall Diffusers

2010 ◽  
Author(s):  
Bing Wei ◽  
Li Zhang
Keyword(s):  
Energy Consumption ◽  
Flow Field ◽  
Energy Conservation ◽  
Indoor Air ◽  
Air Conditioning ◽  
Air Flow ◽  
Side Wall ◽  
Flow Fields ◽  
Flow Mode ◽  
Indoor Air Flow

The energy consumption of AC (air conditioning) systems in large buildings is normally higher than the energy consumption in smaller buildings, and its indoor air flow field is also more complex than that in small building. To study the air flow mode and the indoor air flow fields in large spaces is of great significance to the energy conservation of AC systems and thermal comfort of the occupants. This paper presents an example using a large building that uses stratified air conditioning delivered through the linear slot sidewall diffusers and perforated sidewall diffusers. Using CFD simulation methods, three air flow field situations were simulated: (1) total air volume supplied from linear slot diffusers located in the middle of a side wall, (2) 50% flow through the linear slot diffusers the remainder supplied through the perforated sidewall diffusers, (3) 30% of the volume supplied with linear slot diffusers, 70% supplied through the perforated sidewall diffusers. The simulated results show that the third airflow mode is the optimal one for the three modes, which is good for achieving energy conservation and a comfortable building thermal environment in buildings with large spacial areas.

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