Numerical Simulation of Flow Fluid in Elbow Pipe Based on FLUENT and the Establishment of the Pressure Model

2015 ◽  
Vol 713-715 ◽  
pp. 39-42 ◽  
Author(s):  
Xiao Yang Lu ◽  
Xin Guang Li ◽  
Jin Ming Liu ◽  
Xiao Li Lu ◽  
Hong Liang Zhu ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Theoretical Basis ◽  
Pipe Wall ◽  
Geometric Parameters ◽  
Analysis Method ◽  
Dimensionless Analysis ◽  
Flow Parameters ◽  
Parameter Variations ◽  
Fluent Simulation ◽  
Simulation Results

According to the FLUENT simulation results of the 90°elbow pipe fluid flow condition, the influence of the pressure distribution about the variation of the flow parameters (v、P0 、ρ) and the geometric parameters (R、d、k=R/d、α、β) is analyzed. By using the dimensionless analysis method, on the basis of the influence of the 32 set of parameter variations on the elbow pipe wall pressure distribution regularity, the pressure qualitative function is established including the geometric parameters and the flow parameters. Through the 155 kinds of the FLUENT simulation results, the fitting software 1stOpt is used to verify the internal pressure model above and fit the undetermined coefficients. The verification shows that the model is of a higher calculation precision and the relative error isn’t exceeding 0.003%. It provides a theoretical basis to check the strength of the bend and design the pipeline with high pressure and speed.

scholarly journals Effect of Pressure Distribution on the Energy Dissipation of Lap Joints under Equal Pre-tension Force

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 320-328
Author(s):  
Delin Sun ◽  
Minggao Zhu
Keyword(s):  
Energy Dissipation ◽  
Pressure Distribution ◽  
Theoretical Basis ◽  
Lap Joints ◽  
Power Exponent ◽  
Lap Joint ◽  
Stick Slip ◽  
Pressure Distributions ◽  
Hysteretic Characteristics ◽  
Effective Use

Abstract In this paper, the energy dissipation in a bolted lap joint is studied using a continuum microslip model. Five contact pressure distributions compliant with the power law are considered, and all of them have equal pretension forces. The effects of different pressure distributions on the interface stick-slip transitions and hysteretic characteristics are presented. The calculation formulation of the energy dissipation is introduced. The energy dissipation results are plotted on linear and log-log coordinates to investigate the effect of the pressure distribution on the energy distribution. It is shown that the energy dissipations of the lap joints are related to the minimum pressure in the overlapped area, the size of the contact area and the value of the power exponent. The work provides a theoretical basis for further effective use of the joint energy dissipation.

A Bandgap Reference with Temperature Coefficient of 13.2 ppm/°C

2014 ◽  
Vol 981 ◽  
pp. 66-69
Author(s):  
Ming Yuan Ren ◽  
En Ming Zhao
Keyword(s):  
Power Supply ◽  
Process Simulation ◽  
Output Voltage ◽  
Operating Temperature ◽  
Cmos Process ◽  
Bandgap Reference ◽  
Analysis Method ◽  
Operation Condition ◽  
Reference Circuit ◽  
Simulation Results

This paper presents a design and analysis method of a bandgap reference circuit. The Bandgap design is realized through the 0.18um CMOS process. Simulation results show that the bandgap circuit outputs 1.239V in the typical operation condition. The variance rate of output voltage is 0.016mV/°C? with the operating temperature varying from-60°C? to 160°C?. And it is 3.27mV/V with the power supply changes from 1.8V to 3.3V.

Influences of Diaphragm Springs on Operation Performances of Sight-Stabilizing Mechanism

2011 ◽  
Vol 211-212 ◽  
pp. 384-388
Author(s):  
Gui Mei Guo ◽  
Lin Hong
Keyword(s):  
Rigid Body ◽  
Structural Parameters ◽  
Angular Displacement ◽  
Kinematics And Dynamics ◽  
Analysis Method ◽  
Structure Form ◽  
Simulation Results ◽  
Fix Point ◽  
The Moment

Sight-stabilizing mechanisms controlled by diaphragm springs and other damping elements is an important subordinate system of airborne sight stabilizing System. The performances of sight-stabilizing system depend on the characteristics of kinematics and dynamics of the system in a great extent. Among various external moments acting on the rod of the manipulator, such as those moments caused by damper, positioning spring, and restoration spring, the forces by diaphragm springs are most obvious. According to the structure form and motion peculiarity, the rod can be equivalent to a rigid body turning around a fix point. Simulation results reveal that the moment of the restoration spring to the rod is proportional to the angular displacement, and that the moment is the most prominent factor influencing the operating performances among all these moments. Through reasonable adjustments of structural parameters of the restoration spring, the performances of the sight-stabilizing system can be improved greatly; the analysis method provides a basis for guiding the design of concerned structural parameters of sight-stabilizing system.

Study on the Thermo-Hydrodynamic of a Dry Gas Seal in Helium Circulator for High Temperature Gas-Cooled Reactor

2011 ◽  
Author(s):  
Jianshu Lin ◽  
Hong Wang
Keyword(s):  
High Temperature ◽  
Film Flow ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Analysis Method ◽  
Dry Gas Seal ◽  
Safety Requirements ◽  
Simulation Results ◽  
Gas Seals ◽  
High Temperature Gas

A comprehensive analysis method is proposed to resolve the problem of simulating a complex thermo-flow with two kinds of distinct characteristic length in the dry gas seal, and a conjugated simulation of the complicated heat transfer and the gas film flow is carried out by using the commercial CFD software CFX. By using the proposed method, a three dimensional of velocity and pressure field in the gas film flow and the temperature distribution within the sealing rings are investigated for three kinds of film thickness, respectively. A comparison of thermo-hydrodynamics of the dry gas seals is conducted between the sealed gas of air and helium. The latter one is used in a helium circulator for High Temperature Gas-cooled Reactor (HTGR). From comparisons and discussions of a series of simulation results, it will be found that the comprehensive proposal is effective and simulation results are reasonable, and the maximum temperature rise in the dry gas seal is within the acceptable range of HTGR safety requirements.

scholarly journals Discussion on the Theoretical Basis for Cross-Over Method Applied to Downhole Wave Velocity Test

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qing Dong ◽  
Zheng-hua Zhou ◽  
Su Jie ◽  
Bing Hao ◽  
Yuan-dong Li
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Wave Velocity ◽  
Theoretical Basis ◽  
Influence Factors ◽  
P Wave ◽  
Engineering Practice ◽  
S Wave ◽  
Simulation Results ◽  
The Cross

At engineering practice, the theoretical basis for the cross-over method, used to obtain shear wave arrival time in the downhole method of the wave velocity test by surface forward and backward strike, is that the polarity of P-wave keeps the same, while the polarity of S-wave transforms when the direction of strike inverted. However, the characteristics of signals recorded in tests are often found to conflict with this theoretical basis for the cross-over method, namely, the polarity of the P-wave also transforms under the action of surface forward and backward strike. Therefore, 3D finite element numerical simulations were conducted to study the validity of the theoretical basis for the cross-over method. The results show that both shear and compression waves are observed to be in 180° phase difference between horizontal signal traces, consistent with the direction of excitation generated by reversed impulse. Furthermore, numerical simulation results prove to be reliable by the analytic solution; it shows that the theoretical basis for the cross-over method applied to the downhole wave velocity test is improper. In meanwhile, numerical simulations reveal the factors (inclining excitation, geophone deflection, inclination, and background noise) that may cause the polarity of the P-wave not to reverse under surface forward and backward strike. Then, as to reduce the influence factors, we propose a method for the downhole wave velocity test under surface strike, the time difference of arrival is based between source peak and response peak, and numerical simulation results show that the S-wave velocity by this method is close to the theoretical S-wave velocity of soil.

scholarly journals Comparison and analysis of calculation of Bridge backwater based on Mike21 hydrodynamic model

2021 ◽  
Vol 233 ◽  
pp. 03043
Author(s):  
Jiang Chuan Liu ◽  
Zhu Qiu Hu ◽  
Mao Yuan Zhu
Keyword(s):  
Theoretical Basis ◽  
Impact Analysis ◽  
Navier Stokes ◽  
Efficiency Coefficient ◽  
Navier Stokes Equation ◽  
The Real ◽  
Comparison And Analysis ◽  
Simulation Results ◽  
The Difference ◽  
Local Water

The construction of bridges and other structures across the river will affect the flood discharge capacity and local water potential of the river.Based on navier-Stokes equation of MIKE21FM hydrodynamic module, this paper carries out two-dimensional numerical simulation of part of Shixi River. By optimizing the grid near the piers to reduce the difference brought by the terrain generalized grid of the real river, it simulates and analyzes the length of the curve of yong-high and Yong-water under different flood frequencies,the Nash-Sutcliffe efficiency coefficient and relative error analysis are used to verify the rationality of the results. The simulation results can accurately reflect the real changes of river water level, It provides a theoretical basis for flood impact analysis.

scholarly journals Global Finite-Time Stabilization Problem of Affine Nonlinear Systems with Unknown Functions

2021 ◽  
Author(s):  
Fujin Jia ◽  
Junwei Lu ◽  
Yong-Min Li ◽  
Fangyuan Li
Keyword(s):  
Nonlinear Systems ◽  
Finite Time ◽  
Control Algorithm ◽  
Lyapunov Analysis ◽  
Stabilization Problem ◽  
Analysis Method ◽  
Control Approach ◽  
Affine Nonlinear Systems ◽  
Simulation Results ◽  
Finite Time Stabilization

In this paper, the global finite-time stabilization (FTS) of nonlinear systems with unknown functions (UFs) is studied. Firstly, in order to deal with UFs, a Lemma is proposed to avoid the Assumptions of UFs. Secondly, based on this Lemma, the control algorithm designed by using backstepping has no partial derivative of virtual controllers, so it avoids the “differential explosion” problem of backstepping. Thirdly, by using Lyapunov analysis method, backstepping and FTS method, a global FTS control algorithm of nonlinear systems with UFs is proposed. Finally, the feasibility of developed control approach is illustrated by the simulation results of a manipulator.

Study the Influence of Geometric Parameters on Springback in T-Section Aluminum Alloy Window Trim Strip Sheets Forming

2018 ◽  
Vol 920 ◽  
pp. 70-76 ◽  
Author(s):  
Bao Hang Zhu ◽  
Yi Xi Zhao ◽  
Zhong Qi Yu ◽  
Hui Yan
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Geometric Parameters ◽  
Finite Element Models ◽  
Quality Requirement ◽  
Forming Process ◽  
Assembly Quality ◽  
Simulation Results ◽  
In The Beginning ◽  
Springback Control

The T-section aluminum alloy window trim strip sheets are used to improve vehicle appearance. As the mobile scenery line, these window trim strips with claws need high forming accuracy to meet good assembly quality requirement. The top portion of the T-section sheet is stamped to form an edge flange structure. Springback control is essential in forming process. In this paper, the influence of the window trim strip geometric parameters on forming springback is studied. Some finite element models of the process were built with the Dynaform software. The simulation results were verified experimentally. The main conclusions include as belows: The different heights of the stiffeners part in T-section change the stiffness of the part. Although the stiffeners part does not participate in the forming, it also has springback in the forming process. So, it is necessary to study the influence of the flanging part width (W) and the stiffeners part height (H) of the T-section on springback. We set W to 15 mm and change the value of H value according to the real product. The value of springback increases with the increase of H value in the beginning. After ratio of H/W increases to 0.6, the value of springback fluctuates with the increase of H value. When ratio of H/W is about 0.5, the springback values are mostly less than ± 0.5 mm in key sections, which is acceptable.

Study on Modeling and Kinematics Analysis of an Assistant Robot

2013 ◽  
Vol 299 ◽  
pp. 48-51
Author(s):  
Ramadhani O. Kivugo ◽  
Zhong Min Wang
Keyword(s):  
Physical Characteristics ◽  
Geometric Parameters ◽  
Simulation Studies ◽  
Analysis Method ◽  
Kinematics Analysis ◽  
Robot System ◽  
Simulation Experiments ◽  
Kinematics Model

Firstly, model of an assistant robot is built by UG software based on analysis to human exoskeleton system. Secondly, for establishing its kinematics model of this assistant robot, physical characteristics, practical geometric parameters and restriction relations are considered, and then this model is exported to ADAMS environment. Thirdly, simulation studies to the assistant robot system are carried out by ADAMS, and its kinematics performances are analyzed. Simulation experiments verify the validity and feasibility of the modeling and kinematics analysis method.

Effect of Geometric Parameters in the Upsetting and Extruding Riveting Process on the Quality of Riveted Joints

2015 ◽  
Vol 651-653 ◽  
pp. 1439-1444 ◽  
Author(s):  
Wei Jia Li ◽  
Lian Fa Yang
Keyword(s):  
Hole Diameter ◽  
Geometric Parameters ◽  
Hole Wall ◽  
Riveted Joints ◽  
Riveting Process ◽  
Simulation Results

Upsetting and extruding riveting is a new joining method, which is mainly used to join castings. In order to investigate the effect of geometric dimensions of punch and upper sheet hole diameter on the quality of joints, models with different geometric parameters were simulated via ABAQUS. According to the simulation results, the riveting process could be divided into five stages. Besides, diameter difference on rivet tail and interference value on upper sheet hole wall were selected as indicators to evaluate quality of joints. And a group of parameters is obtained for a better quality of joints. Finally, the simulation results were validated through experiments.

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