scholarly journals Study of hydraulic resistance of tangential swirlers

2021 ◽  
Vol 2094 (5) ◽  
pp. 052029
Author(s):  
N A Voinov ◽  
D A Zemtsov ◽  
A V Bogatkova ◽  
N V Deryagina
Keyword(s):  
Drag Coefficient ◽  
Hydraulic Resistance ◽  
Experimental Research ◽  
Process Parameters ◽  
Simulation Modelling ◽  
Hydraulic Drag ◽  
Comsol Multiphysics ◽  
Circular Channel ◽  
Pressure Fields ◽  
Wide Range

Abstract This article presents the results of experimental research and simulation of the hydraulic drag of tangential swirlers. Three types of swirler devices made with straight, profiled, and circular channel walls were studied within a wide range of design and process parameters. Simulation modelling on the Comsol Multiphysics platform was used to calculate hydraulic drag and determine the velocity and pressure fields. This allowed obtaining a dependence of the hydraulic drag coefficient of the investigated swirlers and identifying parameters affecting their hydraulic drag.

scholarly journals UV Nanoimprint Lithography: Geometrical Impact on Filling Properties of Nanoscale Patterns

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 822
Author(s):  
Christine Thanner ◽  
Martin Eibelhuber
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Nanoimprint Lithography ◽  
Failure Modes ◽  
Production Method ◽  
Efficient Production ◽  
Comprehensive Overview ◽  
Replication Method ◽  
Wide Range ◽  
Pattern Size

Ultraviolet (UV) Nanoimprint Lithography (NIL) is a replication method that is well known for its capability to address a wide range of pattern sizes and shapes. It has proven to be an efficient production method for patterning resist layers with features ranging from a few hundred micrometers and down to the nanometer range. Best results can be achieved if the fundamental behavior of the imprint resist and the pattern filling are considered by the equipment and process parameters. In particular, the material properties and pattern size and shape play a crucial role. For capillary force-driven filling behavior it is important to understand the influencing parameters and respective failure modes in order to optimize the processes for reliable full wafer manufacturing. In this work, the nanoimprint results obtained for different pattern geometries are compared with respect to pattern quality and residual layer thickness: The comprehensive overview of the relevant process parameters is helpful for setting up NIL processes for different nanostructures with minimum layer thickness.

scholarly journals Influence of Tool Geometry and Process Parameters on the Properties of Friction Stir Spot Welded Multiple (AA 5754 H111) Aluminium Sheets

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1157
Author(s):  
Danka Labus Zlatanovic ◽  
Sebastian Balos ◽  
Jean Pierre Bergmann ◽  
Stefan Rasche ◽  
Milan Pecanac ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Spot Welding ◽  
Minimum Energy ◽  
Tool Geometry ◽  
Friction Stir ◽  
Minimum Energy Consumption ◽  
Punch Test ◽  
Wide Range ◽  
Lap Welding

Friction stir spot welding is an emerging spot-welding technology that offers opportunities for joining a wide range of materials with minimum energy consumption. To increase productivity, the present work addresses production challenges and aims to find solutions for the lap-welding of multiple ultrathin sheets with maximum productivity. Two convex tools with different edge radii were used to weld four ultrathin sheets of AA5754-H111 alloy each with 0.3 mm thickness. To understand the influence of tool geometries and process parameters, coefficient of friction (CoF), microstructure and mechanical properties obtained with the Vickers microhardness test and the small punch test were analysed. A scanning acoustic microscope was used to assess weld quality. It was found that the increase of tool radius from 15 to 22.5 mm reduced the dwell time by a factor of three. Samples welded with a specific tool were seen to have no delamination and improved mechanical properties due to longer stirring time. The rotational speed was found to be the most influential parameter in governing the weld shape, CoF, microstructure, microhardness and weld efficiency. Low rotational speeds caused a 14.4% and 12.8% improvement in joint efficiency compared to high rotational speeds for both tools used in this investigation.

Numerical investigation of anguilliform locomotion by the SPH method

2019 ◽  
Vol 30 (1) ◽  
pp. 328-346 ◽  
Author(s):  
Amin Rahmat ◽  
Hossein Nasiri ◽  
Marjan Goodarzi ◽  
Ehsan Heidaryan
Keyword(s):  
Drag Coefficient ◽  
Numerical Investigation ◽  
Sph Method ◽  
Content Type ◽  
Aquatic Locomotion ◽  
Wide Range ◽  
Particle Hydrodynamics ◽  
Dummy Particles ◽  
Smoothed Particle ◽  
Sph Algorithm

Purpose This paper aims to introduce a numerical investigation of aquatic locomotion using the smoothed particle hydrodynamics (SPH) method. Design/methodology/approach To model this problem, a simple improved SPH algorithm is presented that can handle complex geometries using updatable dummy particles. The computational code is validated by solving the flow over a two-dimensional cylinder and comparing its drag coefficient for two different Reynolds numbers with those in the literature. Findings Additionally, the drag coefficient and vortices created behind the aquatic swimmer are quantitatively and qualitatively compared with available credential data. Afterward, the flow over an aquatic swimmer is simulated for a wide range of Reynolds and Strouhal numbers, as well as for the amplitude envelope. Moreover, comprehensive discussions on drag coefficient and vorticity patterns behind the aquatic are made. Originality/value It is found that by increasing both Reynolds and Strouhal numbers separately, the anguilliform motion approaches the self-propulsion condition; however, the vortices show different pattern with these increments.

Experimental Research of Electrochemical Mechanical Polishing (ECMP) for Micro Tool Electrode

2011 ◽  
Vol 314-316 ◽  
pp. 1846-1850 ◽  
Author(s):  
Shuai Guo ◽  
Z.N Guo ◽  
Hong Ping Luo ◽  
Wen Cai Gu
Keyword(s):  
Experimental Research ◽  
Process Parameters ◽  
Mechanical Polishing ◽  
Working Fluid ◽  
Tool Electrode ◽  
Electrical Parameters ◽  
Electrochemical Mechanical Polishing ◽  
Major Process ◽  
Micro Tool ◽  
Quantitative Analyses

The mechanism of the elctrochemical mechanical polishing (ECMP) technology for micro tool electrode was investigated. In this paper, suitable major process parameters on the surface quality were evaluated, the major parameters contains electrical parameters, machining gap, the working fluid and other factors. In quantitative analyses, the process of the ECMP technology were conducted. The roughness of the workpiece was reduced from a relatively high value to a mirror effect.

Experimental Research on Rotating Skimmer

2003 ◽  
Author(s):  
Minoru Chino ◽  
Kenji Takizawa ◽  
Takashi Yabe
Keyword(s):  
Experimental Research ◽  
Rotational Speed ◽  
Rotation Speed ◽  
Experimental Results ◽  
Injection System ◽  
Benchmark Test ◽  
Injection Speed ◽  
Structure Interaction ◽  
Wide Range ◽  
Computer Codes

This paper provides the experimental results on skimmer and gives some detailed information useful for benchmark test of computer codes that are now able to simulate the fluid-structure interaction. For this purpose, we specially designed the injection system that imposes reproducible rotational speed and injection speed on the skipper. The effect of rotation is discussed by changing rotation speed in a wide range.

Drag Coefficient and Two-Phase Friction Multiplier on Tube Bundles Subjected to Two-Phase Cross-Flow

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
W. G. Sim ◽  
Njuki W. Mureithi
Keyword(s):  
Drag Coefficient ◽  
Void Fraction ◽  
Euler Number ◽  
Tube Bundle ◽  
Cross Flow ◽  
Water Mixture ◽  
Duct Flow ◽  
Two Phase ◽  
Mass Fluxes ◽  
Wide Range

An approximate analytical model, to predict the drag coefficient on a cylinder and the two-phase Euler number for upward two-phase cross-flow through horizontal bundles, has been developed. To verify the model, two sets of experiments were performed with an air–water mixture for a range of pitch mass fluxes and void fractions. The experiments were undertaken using a rotated triangular (RT) array of cylinders having a pitch-to-diameter ratio of 1.5 and cylinder diameter 38 mm. The void fraction model proposed by Feenstra et al. was used to estimate the void fraction of the flow within the tube bundle. An important variable for drag coefficient estimation is the two-phase friction multiplier. A new drag coefficient model has been developed, based on the single-phase flow Euler number formulation proposed by Zukauskas et al. and the two-phase friction multiplier in duct flow formulated by various researchers. The present model is developed considering the Euler number formulation by Zukauskas et al. as well as existing two-phase friction multiplier models. It is found that Marchaterre's model for two-phase friction multiplier is applicable to air–water mixtures. The analytical results agree reasonably well with experimental drag coefficients and Euler numbers in air–water mixtures for a sufficiently wide range of pitch mass fluxes and qualities. This model will allow researchers to provide analytical estimates of the drag coefficient, which is related to two-phase damping.

Hydraulic Actuator Tuning in the Control of a Rotating Flexible Beam Mechanism

1995 ◽  
Author(s):  
Michael J. Panza ◽  
Roger W. Mayne
Keyword(s):  
Hydraulic Resistance ◽  
System Model ◽  
Flexible Beam ◽  
Hydraulic Actuator ◽  
Control Effort ◽  
Actuation System ◽  
Wide Range ◽  
Position Feedback ◽  
Simulation Results ◽  
Beam Mechanism

Abstract The end point position and vibration control of a rotating flexible beam mechanism driven by a hydraulic cylinder actuator is considered. An integrated nonlinear system model comprised of beam dynamics, hydraulic actuator, control valves, and control scheme is presented. Control based on simple position feedback along with a hydraulic actuation system tuned to suppress beam vibration over a wide range of angular motion is investigated. For positioning to small to moderate mechanism angles, a linear system model with the actuator tuned for good open loop performance is developed. Actuator tuning is accomplished by varying the system hydraulic resistance according to a dimensionless parameter defining the interaction between the actuator and flexible beam. Simulation results for a closed loop system indicate that this simple tuned control provides comparable performance and requires less control effort than an untuned system with a more complex state feedback optimal controller. To compensate for geometric nonlinearities that cause instability when positioning to large mechanism angles, an active actuator tuning scheme based on continuous variation of hydraulic resistance is proposed. The active variable resistance controller is combined with simple position feedback and designed to provide a constant dimensionless actuator-flexible beam interaction parameter throughout the motion. Simulation results are presented to show the stabilizing effect of this control strategy.

Explosion Welding: Process Evolution and Parameters Optimization

2018 ◽  
Vol 941 ◽  
pp. 1558-1564 ◽  
Author(s):  
Girolamo Costanza ◽  
Maria Elisa Tata ◽  
Diego Cioccari
Keyword(s):  
Process Parameters ◽  
Welding Process ◽  
Explosion Welding ◽  
Parameters Optimization ◽  
Comprehensive Understanding ◽  
Laminate Composites ◽  
Materials Properties ◽  
Key Points ◽  
Joint Properties ◽  
Wide Range

The development of explosion welding (EXW) technology underwent a stop as soon as it was introduced, however, in the recent years an increasing interest was found due to the wide range of materials which can be welded, similar and especially dissimilar ones. In addition to the high quality, such welded joints show a good compromise among the involved materials properties. Literature does not provide a comprehensive understanding of the whole mechanism and occurring phenomena but is mostly limited to analyse just some process parameters, like the investigations on joint properties that can be achieved if process takes place under vacuum or open air. In this work some key points are discussed to describe the evolution step of the process and the innovations introduced like the MIL (metallic-intermetallic laminate) composites for aerospace industry. Process parameters are analyzed to highlight the positive and negative aspects, the experiments in the laboratory will be described to confine the explosion to the joint and in particular to minimize the explosion energy and to improve the efficiency of the technique. At last some significant applications where this technique is widely used are showed.

scholarly journals Computation of Pressure Fields around a Two-Dimensional Circular Cylinder Using the Vortex-In-Cell and Penalization Methods

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Seung-Jae Lee ◽  
Jun-Hyeok Lee ◽  
Jung-Chun Suh
Keyword(s):  
Circular Cylinder ◽  
Solid Body ◽  
Pressure Field ◽  
Stokes Equations ◽  
Computational Cost ◽  
Fixed Time ◽  
Computational Grids ◽  
Penalty Term ◽  
Pressure Fields ◽  
Wide Range

The vorticity-velocity formulation of the Navier-Stokes equations allows purely kinematical problems to be decoupled from the pressure term, since the pressure is eliminated by applying the curl operator. The Vortex-In-Cell (VIC) method, which is based on the vorticity-velocity formulation, offers particle-mesh algorithms to numerically simulate flows past a solid body. The penalization method is used to enforce boundary conditions at a body surface with a decoupling between body boundaries and computational grids. Its main advantage is a highly efficient implementation for solid boundaries of arbitrary complexity on Cartesian grids. We present an efficient algorithm to numerically implement the vorticity-velocity-pressure formulation including a penalty term to simulate the pressure fields around a solid body. In vorticity-based methods, pressure field can be independently computed from the solution procedure for vorticity. This clearly simplifies the implementation and reduces the computational cost. Obtaining the pressure field at any fixed time represents the most challenging goal of this study. We validate the implementation by numerical simulations of an incompressible viscous flow around an impulsively started circular cylinder in a wide range of Reynolds numbers: Re=40, 550, 3000, and 9500.

Sign in / Sign up

Export Citation Format

Share Document