Analysis and Simulation of Air Flow Field Surrounding Grinding Wheel

2014 ◽  
Vol 1027 ◽  
pp. 12-15 ◽  
Author(s):  
Chun Yu Wang ◽  
Lei Zhang ◽  
Chun Feng Yang
Keyword(s):  
Flow Field ◽  
Contact Zone ◽  
High Speed ◽  
Thermal Damage ◽  
Air Flow ◽  
Element Model ◽  
Simulation Method ◽  
Grinding Wheel ◽  
Speed Increase ◽  
Conventional Grinding

In grinding, high specific heat is generated and hence it is very important for the fluid to remove heat from the grinding contact zone to avoid thermal damage to the workpiece surface and/or sub-surface layers. In conventional grinding, a stiff air layer is generated due to the rotation of the porous grinding wheel at high speed. Hence, most of fluid isn’t penetrated into the grinding contact zone because of the stiff air layer around the grinding wheel. To improve grinding fluid cooling effection and avoid thermal damage, it is necessary to analyze the air flow and stiff air layer around the grinding wheel. Based on fluid dynamics and mathematical simulation method, the 3D finite element model of the air flow field around the grinding wheel is developed. The air flow pressure field and flow velocity near the grinding zone are analyzed. In results, the pressure and the velocity of the air flow near the grinding zone increase with the wheel speed increase, and the pressure and the velocity of the air flow near the grinding zone increase with the minimum gap between the grinding wheel and the workpiece reducing. After the air is drived by the grinding wheel into the high pressure area near the grinding zone, the air flows around both sides of the grinding wheel and there are no obvious returning air flow phenomena.

scholarly journals Numerical Simulation of Gear Heat Distribution in Meshing Process Based on Thermal-structural Coupling

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Peixiang Xu
Keyword(s):  
Heat Conduction ◽  
High Speed ◽  
Element Model ◽  
Simulation Method ◽  
Spur Gear ◽  
Gear Transmission ◽  
Heat Distribution ◽  
Heavy Load ◽  
Structural Coupling ◽  
Meshing Process

The thermal balance state of high-speed and heavy-load gear transmission system has an important influence on the performance and failure of gear transmission and the design of gear lubrication system. Excessive surface temperature of gear teeth is the main cause of gluing failure of gear contact surface. To investigate the gear heat distribution in meshing process and discuss the effect of thermal conduction on heat distribution,a finite element model of spur gear is presented in the paper which can represent general involute spur gears. And a simulation approach is use to calculate gear heat distribution in meshing process. By comparing with theoretical calculation, the correctness of the simulation method is verified, and the heat distribution of spur gear under the condition of heat conduction is further analyzed. The difference between the calculation results with heat conduction and without heat conduction is compared. The research has certain reference significance for dry gear hobbing and the same type of thermal-structural coupling analysis.

A Stochastic Immersed Model of Breakup Characteristics in Dense Air Atomization Flow Field

2020 ◽  
Author(s):  
Tian Deng ◽  
Xingming Ren ◽  
Yaxuan Li
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Large Scale ◽  
Gas Flow ◽  
Liquid Core ◽  
Average Diameter ◽  
Simulation Method ◽  
Spray Angle ◽  
Random Structure ◽  
Momentum Ratio

Abstract For the low-speed liquid injected into the high-speed strong turbulent gas flow in the same direction, the atomization is a transient-intensive spray, and there are many factors affecting and controlling the atomization. In this paper, the distribution and characteristics of the liquid breakup in the air atomized flow field are analyzed. A stochastic immersed model to simulate the liquid core is developed, in which, the liquid core is regarded as an immersed porous medium with a random structure, and the probability of existence is used to simulate the position of the liquid core. The initial fragmentation mechanism of the air blast atomization is applied as the global variables of the stochastic process. Using the above stochastic immersed model, combined with the Large Eddy Simulation method, the numerical simulation of the downstream flow field of a coaxial jet air atomizing nozzle is carried out. Additional force is added to the momentum equation in the LES model. Instantaneous air velocity at the air-liquid interface is characterized by instantaneous liquid phase velocity at the same time. The size of the initial atomized droplet satisfies a probability distribution, and once the large droplets are formed, the Lagrangian method is used to track the droplets. The comparison between the simulation results and the experimental results shows that this stochastic immersed model can quickly capture the information of length and position of the liquid nucleus. When the gas-liquid momentum ratio M is 3∼10000, the liquid core length can be predicted more accurately. When M>10, the prediction result is much better than phenomenological model. This model is capable of capturing flow field structures such as recirculation zones and large-scale vortices. The results of initial spray angle from experiment expression give slightly better agreement with this model. Increasing the momentum ratio leads to decreasing of the initial spray angle. The particle size of the droplets near the nozzle can be accurately predicted, especially when the gas velocity is large (bigger than 60 m/s), and the average diameter prediction error of the droplets is less than 10%.

Investigation of the instability mechanisms in a turbocharger centrifugal compressor with a vaneless diffuser by means of unsteady simulations

2016 ◽  
Vol 231 (11) ◽  
pp. 1558-1567 ◽  
Author(s):  
Xinqian Zheng ◽  
Anxiong Liu ◽  
Zhenzhong Sun
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
High Speed ◽  
Simulation Method ◽  
Great Accuracy ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Vaneless Diffuser ◽  
Unstable Flow ◽  
Low Velocity

The stable-flow range of a compressor is predominantly limited by surge and stall. In this paper, an unsteady simulation method was employed to investigate the instability mechanisms of a high-speed turbocharger centrifugal compressor with a vaneless diffuser. In comparison with the variation in the pressure obtained by dynamic experiments on the same compressor, unsteady simulations show a great accuracy in representing the stall behaviour. The predicted frequency of the rotating stall is 22.5% of the rotor frequency, which agrees with to the value for the high-frequency short-term rotating stall obtained experimentally. By investigating the instability of the flow field, it is found that the unstable flow of the turbocharger compressor at high rotational speeds is caused by the tip clearance leakage flow and the ‘backflow vortices’ originating from the interaction of the incoming flow and the backflow in the tip region of the passages. The asymmetric volute helps to induce the occurrence of stall in certain impeller passages because it generates an asymmetric flow field. The high-pressure low-velocity area from the 180° circumferential position to the 270° circumferential position is dominant and strengthens the backflow at the trailing edge of the impeller, finally triggering the stall.

Air Flow Field and Fiber Motion in a Swirl Die Melt-Blowing Process

2013 ◽  
Vol 690-693 ◽  
pp. 2861-2865
Author(s):  
Sheng Xie ◽  
Yuan Sheng Zheng ◽  
Yong Chun Zeng
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Air Flow ◽  
High Speed Camera ◽  
Important Process ◽  
Melt Blowing ◽  
Spiral Motion ◽  
Fiber Motion ◽  
Fiber Path ◽  
The Relationship

Melt blowing is an important process for producing nanofibrous nonwovens. Compared to another technology for producing nanofibrous nonwovens, electrospinning, melt blowing applies high-speed air flow field to attenuate the extruded polymer jet. In this study, the air flow field of a swirl die melt-blowing process was simulated by CFD software, Fluent 6.3. The swirling air profile was shown. Meanwhile, a high-speed camera was used to capture the fiber path below a single-orifice melt-blowing swirl die. The spiral motion of the fiber was revealed. The relationship between the fiber path and the air flow field was discussed. This paper shows the relationship between the fiber path and the air flow field in a swirl die melt-blowing process.

Centrifugal Internal Grinding by Assembled Wheel with Radially Mobile Segments

2016 ◽  
Vol 874 ◽  
pp. 85-90 ◽  
Author(s):  
David Blurtsyan
Keyword(s):  
High Temperature ◽  
Heat Generation ◽  
Contact Area ◽  
High Speed ◽  
Air Flow ◽  
Grinding Wheel ◽  
Generation Zone ◽  
Internal Grinding ◽  
Turbulent Air Flow ◽  
Evacuation System

Productivity of internal grinding processes is limited by wheel-workpiece contact area and high temperature generated during grinding. Existing internal grinding methods do not guarantee presence of coolant liquid in the heat generation zone. Usually coolant liquid from external nozzles could not penetrate turbulent air flow around grinding wheel. Assembled wheel with radially mobile segments allows increasing contact area but needs to be supported by more efficient heat evacuation system. New grinding wheel and method of internal grinding are developed and evaluated. New tool generates high speed hydrodynamic circular flow and dynamic wedges of coolant liquid in the cutting zones.

Tool-Chip Friction and Two-Dimensional Numerical Simulation Analysis of High-Speed Milling AISI304

2015 ◽  
Vol 1089 ◽  
pp. 377-380
Author(s):  
Lin Lin Guo ◽  
Guang Hui Li ◽  
Ning Xia Yin ◽  
Guang Yu Tan
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Simulation Analysis ◽  
Chip Morphology ◽  
Element Model ◽  
Simulation Method ◽  
State Theory ◽  
Friction Model ◽  
Two Dimensional ◽  
High Speed Milling

The physical friction system model was established between the tool and the chip based on the analysis of tri-bological behavior of high speed milling process of the end mill. The finite element simulation method was employed to study the tool-chip friction model, and the two-dimensional(2D) finite element model of milling was created. The numerical results revealed the chip morphology, stress and temperature distribution of the tool-chip contact surface. The tool temperature field distribution provided supports for tool-chip friction state theory and the 3D milling model.

Development of a Computational Model to Visualize Air Flow Into Surrogate Ballistic Wounds

2017 ◽  
Author(s):  
John Ziadat ◽  
Karim H. Muci-Küchler
Keyword(s):  
Spatial Data ◽  
High Speed ◽  
Bacterial Contamination ◽  
Air Flow ◽  
Mechanical Damage ◽  
Element Model ◽  
Model Parameters ◽  
Pressure Dynamics ◽  
Time Histories ◽  
Solid Bodies

In addition to the direct mechanical damage that takes place during a ballistic injury, the formation of the temporary wound cavity creates a suction effect capable of introducing debris, particles, and bacteria from the environment into the wound track. This introduction of bacterial contamination into the wound can give rise to infections which may delay healing or result in more serious problems. Various authors have conducted controlled ballistics experiments placing bacterial contamination on the surface of ballistics gelatin targets to study the effect of parameters such as projectile caliber and speed on the distribution of bacteria along the permanent cavity. The results reported in the literature showed that bacteria were present along the entire surrogate wound track. Understanding the contribution that the formation of the temporary cavity has on the number and distribution of bacteria along the surrogate wound requires the development of experiments to visualize the flow of air during the transient phase of target deformation and the use of numerical simulations to predict variables associated with the flow of air, like pressure-time histories along the projectile path, that cannot be directly measured during experiments. This paper discusses the development of a finite element model using ANSYS Autodyn for the simulation of a small caliber projectile traveling at moderate speeds penetrating a soft tissue surrogate target made of ballistics gelatin. The model uses a Coupled Eulerian-Lagrangian formulation and discretization scheme, which allows for the analysis of not only the deformation of the solid bodies, but also of the flow of air into the wound track. For model validation, the numerical results are compared to spatial data extracted from high speed video recorded during experiments matching key model parameters. Comparisons of the numerical and experimental results indicate that the model is providing reasonable results for the deformations and overall air flow. The predicted pressure dynamics within the simulated wound track clearly suggest that areas of partial vacuum exist within the cavity, which is consistent with the suction effect mentioned by several researchers.

scholarly journals Theoretical Study of the Effect of Instrument Parameters on the Flow Field of Air-Flow Impacting Based Mechanochemical Synthesis

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Yang Tao ◽  
Jun Lin ◽  
Zhao Zhang ◽  
Qiuting Guo ◽  
Jin Zuo ◽  
...  
Keyword(s):  
Flow Field ◽  
Mechanochemical Synthesis ◽  
High Speed ◽  
Theoretical Study ◽  
Air Flow ◽  
Axial Position ◽  
Optimal Conditions ◽  
Nozzle Throat ◽  
Further Development ◽  
Temperature Preparation

The air-flow impacting based mechanochemical synthesis is an alternative strategy to traditional mechanochemical preparations, which has many advantages in terms of reaction temperature, preparation speed, and cleanness. Herein, we theoretically study the effect of instrument parameters, including the axial position of physical target, the diameter difference between nozzle throat and suction pipe, and divergence angles of uniform speed region, on the flow field of the air-flow impacting based mechanochemical synthesis. The optimized parameters have been obtained. Under the optimal conditions, a stable and high-speed air flow is obtained, in which the speed can achieve a Mach number of approximately 2.6. The high-speed air flow is able to easily carry the reacting substances to arrive at the physical target, triggering a chemical reaction. These findings undoubtedly provide a key guideline for further development and application of the air-flow impacting based mechanochemical synthesis.

Design of Robust Grinding Wheel Reciprocating Arrangement for Precision Point-Grinding Machining

2007 ◽  
Vol 329 ◽  
pp. 347-352
Author(s):  
Da Ping Wan ◽  
De Jin Hu ◽  
Li Ming Xu ◽  
Hai Feng Wang ◽  
X.D. Yao
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Self Regulation ◽  
Element Model ◽  
Grinding Wheel ◽  
Hydraulic Pressure ◽  
Analysis Technique ◽  
Time Series Method ◽  
Reciprocating Movement ◽  
Acceleration Signals

This research is to investigate the dynamic characteristics of the grinding process. A kind of robust grinding wheel reciprocating arrangement is schemed out, which realizes the precise point-grinding machining. The grinding wheel reciprocating movement is driven by a linear motor to replace the traditional crank or hydraulic pressure drive device. Based on the time series method, the modal experimental analysis technique has been adopted in this paper. By acquiring acceleration signals of multiple positions of the grinding wheel slide, the dynamic characteristics are analyzed and the modal parameters of the structure are identified by virtual analysis program. The boundary condition of the finite element model is adjusted for optimizing its dynamic characteristic. The equivalent substructure is created and modified in order to improve the surface grinding quality. This study has got satisfying results. The grinding wheel movement realizes the self-regulation control and reduces the surface waviness and roughness during high speed point-grinding operation.

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