scholarly journals Workpiece Vibration in Feed Direction Assisted Electrochemical Cutting Using Tube Electrode With Inclined Holes

2021 ◽  
Author(s):  
Tao Yang ◽  
Xiaolong Fang ◽  
Yusen Hang ◽  
Zhengyang Xu ◽  
Yongbin Zeng
Keyword(s):  
Flow Field ◽  
Feed Rate ◽  
Electrochemical Reaction ◽  
Vibrational Amplitude ◽  
Machining Accuracy ◽  
Machining Efficiency ◽  
Feed Direction ◽  
Tube Electrode ◽  
Workpiece Vibration ◽  
The Difference

Abstract Electrochemical cutting using tube electrode with inclined holes is a machining method that directly and obliquely injects electrolyte into the machining gap through inclined jet-flow holes on the sidewall of a tube electrode, allowing the electrochemical cutting of a workpiece. To improve the machining efficiency and accuracy of this cutting technique, a method of workpiece vibration in feed direction assisted electrochemical cutting is proposed in which workpiece vibration along the feed direction rapidly and periodically changes the machining gap. The near-instantaneous increases in the machining gap promotes the waste electrolyte containing electrolytic products to flow down the machining gap. At the same time, the electrochemical reaction time under the non-uniform flow field caused by the inclined downward injection of electrolyte is reduced. The flow field simulation of electrolyte in machining gap indicates that the near-instantaneous increases in the machining gap can improve the flow velocity of electrolyte. Experiment demonstrates that the average feed rate can be increased by 50% and the machining efficiency is superior to that of electrochemical cutting assisted by workpiece non-vibration in feed direction. The difference between the upper and lower slit widths is reduced and the machining accuracy is improved. The effect of the vibrational amplitude and frequency on the machining result is also investigated. Finally, an array slice structure is fabricated on a stainless steel block with a cross-section of 10 mm × 10 mm at average feed rate of 6 mm/s using a vibrational amplitude and frequency of 0.1 mm and 1.5 Hz, respectively.

scholarly journals Geometric Accuracy Improvement by Using Electrochemical Reaming with a Helical Tube Electrode as Post-Processing for EDM

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3564
Author(s):  
Yan Zhang ◽  
Chen Wang ◽  
Yu Wang ◽  
Qin Ni ◽  
Lei Ji
Keyword(s):  
Flow Field ◽  
Surface Quality ◽  
Electrical Discharge Machining ◽  
Cylindrical Tube ◽  
Helical Structure ◽  
Machining Accuracy ◽  
Machining Parameters ◽  
Post Processing ◽  
Tube Electrode ◽  
Helical Tube

Electrochemical reaming using a helical tube electrode together with lateral flushing is proposed as post-processing to improve the machining accuracy and surface quality of holes produced by electrical discharge machining (EDM). The velocity distributions of flushing in the machining gap for a cylindrical tube electrode and for a helical tube electrode were compared using flow field simulations. The role of the helical structure in promoting removal of machining products was illustrated by the results of the flow field simulations for different lateral flushing pressures. The performance of electrochemical reaming as post-processing in improving machining accuracy and surface quality was verified by comparative experiments examining the exit circularity error, taper, and surface morphology of machined holes. Finally, an optimum combination of machining parameters was obtained through a process parameter optimization experiment.

scholarly journals Research on Stagger Coupling Mode of Pulse Duration and Tool Vibration in Electrochemical Machining

2018 ◽  
Vol 8 (8) ◽  
pp. 1296 ◽  
Author(s):  
Xiaochen Jiang ◽  
Jia Liu ◽  
Di Zhu ◽  
Mingming Wang ◽  
Ningsong Qu
Keyword(s):  
Pulse Duration ◽  
Feed Rate ◽  
Electrochemical Machining ◽  
Machining Accuracy ◽  
Electrode Gap ◽  
Tool Vibration ◽  
Coupling Mode ◽  
Machining Localization ◽  
Electrolysis Products ◽  
Gas Void Fraction

Tuning the coupling of pulse duration and tool vibration in electrochemical machining (PVECM) is an effective method to improve machining accuracy and surface quality. In general, the pulse is set at the same frequency as the tool vibration, and a symmetrical distribution is attained at the minimum inter-electrode gap. To analyse the characteristics of the electrolyte fluid flow and of the electrolysis products in the oscillating inter-electrode gap, a dynamic simulation of the PVECM process was carried out. The simulation results indicated that the electrolyte pressure and gas void fraction when the pulse arrived as the inter-electrode gap was narrowing clearly differed from those when the inter-electrode gap was expanding. Therefore, in addition to the traditional symmetry coupling mode, two other coupling modes called the pre-position and the post-position coupling modes are proposed which use a pulse either just before or just after the minimum inter-electrode gap. Comparative experiments involving the feed rate and machining localization were carried out to evaluate the influence of the three coupling modes. In addition, current waveforms were recorded to analyse the differences between the three coupling modes. The results revealed that the highest feed rate and the best machining localization were achieved by using the pre-position coupling mode.

scholarly journals Computed Tomography Image under Optimized Iterative Reconstruction Algorithm to Analyze the Characteristics of Blood Flow Field in Cerebral Aneurysm before and after Stent Implantation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Kunyang Bao ◽  
Chao Liu ◽  
Jin Li ◽  
Xiang Liu ◽  
Wenzhang Luo ◽  
...  
Keyword(s):  
Blood Flow ◽  
Flow Field ◽  
Cerebral Aneurysm ◽  
Iterative Reconstruction ◽  
Stent Implantation ◽  
Cerebral Aneurysms ◽  
Reconstruction Algorithm ◽  
Ct Images ◽  
Iterative Reconstruction Algorithm ◽  
The Difference

In order to analyze the change characteristics of blood flow field in cerebral aneurysms before and after stent implantation, this study first constructed an optimized iterative reconstruction algorithm to reconstruct CT images of patients with cerebral aneurysms and used it to solve the problem of image sharpness. In addition, backprojection image reconstruction algorithm and Fourier transform analytic method were introduced. According to the CT images of cerebral arteries of patients, the lesions were presented in a three-dimensional and visual way through the reconstructed three-dimensional images, thus achieving the effects of simulation and simulation. The results showed that the sensitivity, specificity, and accuracy of the optimized iterative reconstruction algorithm were 90.78%, 83.27%, and 94.82%, which were significantly higher than those of the backprojection image reconstruction algorithm and Fourier transform analysis method, and the difference was statistically significant ( P < 0.05 ). Before operation, the blood flow velocity in the neck of aneurysm was 7.35 × 10−2 m/s, the exit velocity was 1.51 × 10−1 m/s, and the maximum velocity appeared in the upstream part of the exit. After passing through the aneurysm, the blood flow velocity began to decrease gradually, forming a vortex at the top of the tumor. After stent implantation, the neck and outlet velocities of cerebral aneurysm were 9.352 × 10−2 m/s and 1.897 × 10−2 m/s, respectively. The velocity of blood flow decreased after entering the aneurysm, and there was no vortex at the top of the aneurysm. Among the outlet velocities of arterial blood vessels, the velocity before stent implantation was significantly lower than that after stent implantation, and the difference was statistically significant ( P < 0.05 ). Compared with prestent, the shear force distribution on the wall of cerebral aneurysm showed a significant decrease, and the difference was statistically significant ( P < 0.05 ). To sum up, pelvic floor ultrasound based on hybrid iterative reconstruction algorithm has high accuracy in diagnosing the changes of blood flow field in cerebral aneurysms. The application of CT images in the diagnosis of cerebral aneurysms can objectively provide imaging data for clinical practice and has high application value.

scholarly journals Study on Generating Machining Performance of Two-Dimensional Ultrasonic Vibration-Composited Electrolysis/Electro-Discharge Technology for MMCs

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 617
Author(s):  
Jing Li ◽  
Wanwan Chen ◽  
Yongwei Zhu
Keyword(s):  
Ultrasonic Vibration ◽  
Orthogonal Experiment ◽  
Spindle Speed ◽  
Machining Efficiency ◽  
Matrix Composites ◽  
Two Dimensional ◽  
Machining Performance ◽  
Factors Affecting ◽  
Electro Discharge Machining ◽  
Workpiece Vibration

Ultrasonic vibration-composited electrolysis/electro-discharge machining technology (UE/DM) is effective for machining particulate-reinforced metal matrix composites (MMCs). However, the vibration of the tool or workpiece suitable for holes limits the application of UE/DM. To improve the generating machining efficiency and quality of flat and curved surfaces, in this study, we implemented two-dimensional ultrasonic vibration into UE/DM and constructed a novel method named two-dimensional ultrasonic vibration-composited electrolysis/electro-discharge machining (2UE/DM). The influence of vibration on the performance of 2UE/DM compared to other process technologies was studied, and an orthogonal experiment was designed to optimize the parameters. The results indicated that the materiel remove rate (MRR) mainly increased via voltage and tool vibration. The change current was responsible for the MRR in the process. Spindle speed and workpiece vibration were not dominant factors affecting the MRR; the spindle speed and tool and workpiece vibration, which reduced the height difference between a ridge and crater caused by abrasive grinding, were responsible for surface roughness (Ra) and form precision (δ). Additionally, the optimized parameters of 1000 rpm, 3 V, and 5 um were conducted on MMCs of 40 SiCp/Al and achieved the maximum MRR and minimum Ra and δ of 0.76 mm3/min, 3.35 um, and 5.84%, respectively. This study’s findings provide valuable process parameters for improving machining efficiency and quality for MMCs of 2UE/DM.

A Small-Line Segment Dynamic Transition Algorithm Based on Axial Error Tolerance

2016 ◽  
Vol 851 ◽  
pp. 433-438
Author(s):  
Shu Jie Sun ◽  
Hu Lin ◽  
Liao Mo Zheng ◽  
Jin Gang Yu ◽  
Bei Bei Li ◽  
...  
Keyword(s):  
Tool Path ◽  
Maximum Velocity ◽  
Error Tolerance ◽  
Contour Error ◽  
Work Piece ◽  
Machining Accuracy ◽  
Machining Efficiency ◽  
Processing Efficiency ◽  
Dynamic Transition ◽  
Machining Quality

To ensure the machining precision of work piece and improve the machining quality and machining efficiency, a dynamic transition method based on axial machining accuracy is given. Firstly, the maximum machining contour error is computed based on the axial machining accuracy, and the tool path is processed based on the machining contour error to reduce the amount of command points. Secondly, the circle transition method is used to make the tool path smoother and the machining efficiency higher. Finally, the radius of the transition circle is adjusted based on the maximum velocity of each transition circle. The experimental results shows that the method proposed could effectively satisfy the needs of the machining accuracy and improve the processing efficiency, while reduce the amount of path data.

RANS Maneuvering Simulation of Esso Osaka With Rudder and a Body-Force Propeller

2005 ◽  
Vol 49 (02) ◽  
pp. 98-120
Author(s):  
Claus D. Simonsen ◽  
Frederick Stern
Keyword(s):  
Flow Field ◽  
Open Water ◽  
Verification And Validation ◽  
Fair Agreement ◽  
Navier Stokes ◽  
Complex Flow ◽  
Flow Problems ◽  
The Difference ◽  
Propeller Geometry ◽  
Flow Study

A simplified potential theory-based infinite-bladed propeller model is coupled with the Reynolds averaged Navier-Stokes (RANS) code CFDSHIP-IOWA to give a model that interactively determines propeller-hull-rudder interaction without requiring detailed modeling of the propeller geometry. Computations are performed for an open-water propeller, for the Series 60 ship sailing straight ahead and for the appended tanker Esso Osaka in different maneuvering conditions. The results are compared with experimental data, and the tanker data are further used to study the interaction among the propeller, hull, and rudder. A comparison between calculated and measured data for the Series 60 ship shows fair agreement, where the computation captures the trends in the flow, that is, the flow structure and the magnitude of the field quantities together with the integral quantities. For the tanker, the flow study reveals a rather complex flow field in the stern region, where the velocity distribution and propeller loading reflect the flow field changes caused by the different maneuvering conditions. The integral quantities, that is, the propeller, hull, and rudder forces, are in fair agreement with experiments. No formal verification and validation are performed, so the present results are related to previous work with verification and validation of the same model, but without the propeller. For the validated cases, the levels of validation are the same as without the propeller, because the validation uncertainties, that is, the combined experimental and simulation uncertainties, are assumed to be the same for both cases. Based on this, validation is obtained for approximately the same cases as for the without-propeller conditions, but the comparison errors, that is, the difference between experiment and calculation, are different. For instance, the difference between computation and experiment for the ship resistance is generally larger with the propeller than without, whereas the opposite is the case for the rudder drag. Summarizing the results, the method shows encouraging results, and taking the effort related to modeling the propeller into account, the method appears to be useful in connection with studies of rudder-propeller-hull related flow problems, where the real propeller geometry cannot be modeled.

Effects of Circumferential Nonuniform Tip Clearance on Flow Field and Performance of a Transonic Turbine

2020 ◽  
Author(s):  
Yun Zheng ◽  
Xiubo Jin ◽  
Hui Yang ◽  
Qingzhe Gao ◽  
Kang Xu
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Circumferential Direction ◽  
Tip Clearance ◽  
Computational Domain ◽  
Aerodynamic Efficiency ◽  
Aerodynamic Loss ◽  
The Difference ◽  
And Performance ◽  
Downstream Flow

Abstract The numerical study is performed by means of an in-house CFD code to investigate the effect of circumferential nonuniform tip clearance due to the casing ovalization on flow field and performance of a turbine stage. A method called fast-moving mesh is used to synchronize the non-circular computational domain with the rotation of the rotor row. Four different layouts of the circumferential nonuniform clearance are calculated and evaluated in this paper. The results show that, the circumferential nonuniform clearance could reduce the aerodynamic performance of the turbine. When the circumferential nonuniformity δ reaches 0.4, the aerodynamic efficiency decreases by 0.58 percentage points. Through the analysis of the flow field, it is found that the casing ovalization leads to the difference of the size of the tip clearance in the circumferential direction, and the aerodynamic loss of the position of large tip clearance is greater than that of small tip clearance, which is related to the scale of leakage vortex. In addition, the flow field will become nonuniform in the circumferential direction, especially at the rotor exit, which will adversely affect the downstream flow field.

Numerical Study of Effects of Initial Flow Field on Taylor Vortex Flow

2007 ◽  
Author(s):  
H. Furukawa ◽  
M. Hanaki ◽  
T. Watanabe
Keyword(s):  
Flow Field ◽  
Vortex Flow ◽  
Numerical Study ◽  
Outer Cylinder ◽  
Visual Observation ◽  
Taylor Vortex ◽  
Initial Flow ◽  
Taylor Vortex Flow ◽  
The Difference ◽  
Mode Formation

In concentrically rotating double cylinders consisting of a stationary outer cylinder and a rotating inner cylinder, Taylor vortex flow appears. Taylor vortex flow occurs in journal bearings, various fluid machineries, containers for chemical reaction, and other rotating components. Therefore, the analysis of the flow structure of Taylor vortex flow is highly effective for its control. The main parameters that determine the modes of Taylor vortex flow of a finite length are the aspect ratio Γ, Reynolds number Re. Γ is defined as the ratio of the cylinder length to the gap length between cylinders, and Re is determined on the basis of the angular speed of the inner cylinder. Γ was set to be 3.2, 4.8 and 6.8, and Re to be values in the range from 100 to 1000 at intervals of 100. Thus far, a large number of studies on Taylor vortex flow have been carried out; however, the effects of the differences in initial conditions have not yet been sufficiently clarified. In this study, we changed the initial flow field between the inner and outer cylinders in a numerical analysis, and examined the resulting changes in the mode formation and bifurcation processes. In this study, the initial speed distribution factor α was defined to be a function of the initial flow field and set to be 1.0, 0.999, 0.9 and 0.8 for the calculation. As a result, a difference was observed in the final mode depending on the difference in α for each Γ. From this finding, non-uniqueness, which is a major characteristic of Taylor vortex flow, was confirmed. However, no regularities regarding the difference in mode formation were found and the tendency of the mode formation process was not specified. Moreover, the processes of developing the vortex resulting in different final modes were monitored over time by visual observation. Similar flow behaviors were initially observed after the start of the calculation. Then, a bifurcation point, at which the flow changed to a mode depending on α, was observed, and finally the flow became steady. In addition, there was also a difference in the time taken for the flow to reach the steady state. These findings are based on only visual observation. Accordingly, a more detailed analysis at each lattice point and a comparison of physical quantities, such as kinetic energy and enstrophy, will be our future tasks.

Comparative Analysis of Flow Field in Mixed and Non Mixed Gas Electrochemical Machining for Aero-Engine Turbine Blade Cooling Holes

2017 ◽  
Vol 868 ◽  
pp. 166-171
Author(s):  
Zhing Yong Li ◽  
Xiu Ting Wei ◽  
Wen Wen Lu ◽  
Qing Wei Cui
Keyword(s):  
Flow Field ◽  
Flow Velocity ◽  
Turbine Blade ◽  
Electrochemical Machining ◽  
Machining Accuracy ◽  
Mixed Gas ◽  
Turbine Blade Cooling ◽  
Blade Cooling ◽  
Vortex Zone ◽  
Aero Engine

By the cooling holes in aero-engine turbine blade as the research object, this study focuses on two kinds of ECM methods, which are mix gas added to the nonlinear electrolyte (NaNO3) and non-mixed gas. Mixed and non-mixed gas ECM experiments of turbine blade cooling holes were carried out respectively. The corresponding two-dimensional CAD model of cooling hole was constructed combined with the experimental data and theoretical analysis. Numerical simulation analysis was carried out of the flow field base on the above models by using the fluid dynamics analysis software FLUENT. The influence flow velocity and flow velocity distribution on the machining accuracy and efficiency of ECM were investigated in detail. The vortex zone distribution of gas-NaNO3 mixed phase flow field and single NaNO3 solution flow field was analyzed qualitatively. The simulation results indicated that the flow velocity in the machining gap with mixed gas was significantly higher than the velocity during ECM process for cooling holes. The electrolytic products and heat were washed away completely, the electrolyte can be updated in time. Fluid vortex zone distribution was improved obviously, the flow field distribution became more uniform after mixed gas in ECM process. The machining accuracy and efficiency for cooling holes making may be improved greatly with gas mixed in electrolyte NaNO3.

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