Revisiting the theory of positive glow corona with a comprehensive kinetic scheme

2021 ◽  
Author(s):  
Mian Xiao ◽  
Lipeng Liu ◽  
Hengxin He ◽  
Bin Luo ◽  
Junru Che ◽  
...  
Keyword(s):  
Fluid Model ◽  
Negative Ions ◽  
Kinetic Scheme ◽  
Drift Region ◽  
Positive Space Charge ◽  
Simulation Based ◽  
Detailed Simulation ◽  
Simulation Results ◽  
Positive Space ◽  
Peak Value

Abstract The theory of positive glow corona is revisited by performing a detailed simulation based on the fluid model with a comprehensive kinetic scheme (CKS). The kinetic scheme includes 28 species, 127 chemical reactions for N2/O2 mixture. The simulation results are compared with that from an averaged kinetic scheme (AKS) which considers only 5 species and 7 reactions. The two models give similar predictions in terms of discharge current. However, several differences in details of the results bring new physical insights to the theory of positive glow corona. It is shown that, the model with the AKS underestimates the detachment effect that plays an important role in positive glow corona discharge. Moreover, the wave-front of the current pulse calculated by the model with the CKS has a smaller steepness, a lower peak-to-peak value, and a longer rise time. These results are in better agreement with the experimental measurement reported in the literature. It is also found that the positive space charge of glow corona is dominated by O2+ in the ionization layer and by O4+ in the drift region far away from the anode. Negative ions are produced in the ionization layer close to the anode and the main species are O﹣and O3﹣.

The structure of the impulse corona in a rod/plane gap I. The positive corona

1970 ◽  
Vol 315 (1520) ◽  
pp. 1-25 ◽  
Keyword(s):  
Spatial Distribution ◽  
Electric Field ◽  
Space Charge ◽  
Negative Ions ◽  
Corona Discharges ◽  
Theoretical Derivation ◽  
Plane Electrode ◽  
Positive Space Charge ◽  
Positive Ion ◽  
Positive Space

The dissipation of space charge following the growth of impulse corona discharges in positive rod/earthed plane gaps has been measured with an electrostatic fluxmeter. A method is described to determine the spatial distribution and magnitude of the space charge together with the associated electric field. Initial positive ion densities of up to 100 μC m -3 have been found. The total positive space charge deposited in a 40 cm gap at 160 kV is 500 nC. Electrons emitted from the plane electrode as a result of corona channels crossing the gap are shown to be trapped in the discharge space as negative ions. The recovery of the gap over several seconds is largely due to ionic drift to the electrodes. A theoretical derivation of the rate of deionization agrees with observed values.

scholarly journals Electrical Breakdown in Air and in SF6

1995 ◽  
Vol 48 (3) ◽  
pp. 453 ◽  
Author(s):  
R Morrow ◽  
JJ Lowke
Keyword(s):  
Electric Field ◽  
Electric Field Distribution ◽  
Electrical Breakdown ◽  
Negative Ions ◽  
Continuity Equations ◽  
Positive Ions ◽  
Positive Space Charge ◽  
Attachment Coefficient ◽  
Positive Space ◽  
Positive Point

A theory is presented for the development of streamers from a positive point in atmospheric air. The continuity equations for electrons, positive ions, and negative ions are solved simultaneously with Poisson's equation. For an applied voltage of 20 kV across a 20 mm gap, streamers are predicted to cross the gap in 26 ns, and the calculated streamer velocities are in fair agreement with experiment. When the gap is increased to 50 mm for the same voltage, the streamer is predicted not to reach the cathode. In this case an intense electric field front rapidly propagates about 35 mm into the gap in 200 ns. For a further 9�5 �s the streamer slowly moves into the gap, until the electric field at the head of the streamer collapses, and the streamer front stops moving. Finally, only positive space-charge remains; this moves away from the point, allowing the field near the point to recover, giving rise to a secondary discharge near the anode. The electric field distribution is shown to be quite different from that found previously for SF6; this is explained by the much lower attachment coefficient in air compared with that in SF6. These results show that streamers in air have a far greater range than streamers in SF6. This greater range cannot be explained by comparison of the values of E*, the electric field at which ionisation equals attachment.

Modeling and Design of Permanent Magnet Vibration-to-Electrical Power Generator’s Induction Coil

2012 ◽  
Vol 588-589 ◽  
pp. 614-617
Author(s):  
Zhi Hua Wang ◽  
Mei Ling Li ◽  
Jian Zhang ◽  
Li Wang ◽  
Yong Xu
Keyword(s):  
Permanent Magnet ◽  
Electrical Power ◽  
Induction Coil ◽  
Test Results ◽  
Coil Design ◽  
Sinusoidal Vibration ◽  
Electrical Generator ◽  
Simulation Results ◽  
Peak Value

The Equivalent Turn Number of Coil (ETNC) is proposed for induction coil design. Simulation results show that the vibrationonthe induction coil’s structure. The optimized coil is composed by two symmetry parts on the condition of sinusoidal vibration. The effective value of output EMF of optimized coil increases 51.39% than uniform coil’s. In the experiment, the optimized and uniform coils are fabricated with 600 turns and comparatively studied in the same vibration-to-electrical generator. The test results show that the peak-to-peak value and effective value of output EMF of the optimized coil can increase up to 52.59% and 48.76%, respectively, compared with the uniform coil.

Study on Engine Kinematics and Dynamics Simulation Based on COSMOSMotion

2012 ◽  
Vol 503-504 ◽  
pp. 731-734
Author(s):  
Xiao Xu Liu ◽  
Min Chen ◽  
Ai Hua Tang
Keyword(s):  
Virtual Prototype ◽  
Dynamics Simulation ◽  
Kinematics And Dynamics ◽  
Engine Model ◽  
Kinematics Simulation ◽  
Simulation Based ◽  
Calculation Results ◽  
Simulation Results ◽  
Dynamics Simulations

The engine model with 4 cylinders is built by SolidWorks, the kinematics and dynamics simulations of the engine virtual prototype are done by COSMOSMotion, the results of kinematics simulation are checked, there are very small errors between the simulation results and the calculation results according to formulas. The mainly results of dynamics simulation are given. The simulation result consists with the parameters of the engine.

Comparison of Crash Test and Simulation Results for Impact of Silverado Pickup into New Jersey Barrier under Manual for assessing Safety Hardware

2012 ◽  
Vol 2309 (1) ◽  
pp. 114-126 ◽  
Author(s):  
Dhafer Marzougui ◽  
Cing-Dao (Steve) Kan ◽  
Kenneth S. Opiela
Keyword(s):  
New Jersey ◽  
Primary Objective ◽  
Crash Test ◽  
Fe Model ◽  
George Washington ◽  
Statistical Measures ◽  
Detailed Simulation ◽  
Analysis Center ◽  
Simulation Results ◽  
Concrete Barrier

The National Crash Analysis Center (NCAC) at the George Washington University simulated the crash of a 2,270-kg Chevrolet Silverado pickup truck into a standard 32-in. New Jersey shape concrete barrier under the requirements of Test 3–11 of the Manual for Assessing Safety Hardware (MASH). The new, detailed finite element (FE) model for the Chevrolet Silverado was used as the surrogate for the MASH 2270P test vehicle. An FE model of the New Jersey barrier was drawn from the array of NCAC hardware models. The primary objective of this analysis was to simulate the crash test conducted to evaluate how this commonly used, NCHRP 350–approved device would perform under the more rigorous MASH crashworthiness criteria. A secondary objective was to use newly developed verification and validation (V&V) procedures to compare the results of the detailed simulation with the results of crash tests undertaken as part of another project. The crash simulation was successfully executed with the detailed Silverado FE model and NCAC models of the New Jersey concrete barrier. Traditional comparisons of the simulation results and the data derived from the crash test suggested that the modeling provided viable results. Further comparisons employing the V&V procedures provided a structured assessment across multiple factors reflected in the phenomena importance ranking table. Statistical measures of the accuracy of the test in comparison with simulation results provided a more robust validation than previous approaches. These comparisons further confirmed that the model was able to replicate impacts with a 2270P vehicle, as required by MASH.

Numerical Simulation on Thixo-Forging of Magnesium Matrix Composite

2011 ◽  
Vol 189-193 ◽  
pp. 2535-2538 ◽  
Author(s):  
Hong Yan ◽  
Wen Xian Huang
Keyword(s):  
Numerical Simulation ◽  
Matrix Composite ◽  
Metal Flow ◽  
Magnesium Matrix Composite ◽  
Magnesium Matrix ◽  
Simulation Based ◽  
Prior Literature ◽  
Simulation Results ◽  
Computer Numerical Simulation ◽  
Good Agreement

The thixo-forging of magnesium matrix composite was analyzed with computer numerical simulation based on rigid viscoplastic finite element method. The constitutive model of SiCp/AZ61 composite was established in our prior literature. Behavior of metal flow and temperature field were obtained. The differences between traditional forging and thixo-forging processes were analyzed. Results indicated that thixo-forging was better in filling cavity than forging. Simulation results were good agreement with experimental ones.

Reliability-Based Analysis and Optimization of the Gravity Balancing Performance of Spring-Articulated Serial Robots with Uncertainties

2021 ◽  
pp. 1-32
Author(s):  
Vu Linh Nguyen ◽  
Chin-Hsing Kuo ◽  
Po Ting Lin
Keyword(s):  
Pso Algorithm ◽  
Reliability Based Design Optimization ◽  
Swarm Optimization ◽  
Reliability Based Design ◽  
Serial Robots ◽  
Simulation Based ◽  
Serial Robot ◽  
Simulation Results ◽  
Uncertainty Level

Abstract This article proposes a method for analyzing the gravity balancing reliability of spring-articulated serial robots with uncertainties. Gravity balancing reliability is defined as the probability that the torque reduction ratio (the ratio of the balanced torque to the unbalanced torque) is less than a specified threshold. The reliability analysis is performed by exploiting a Monte Carlo simulation (MCS) with consideration of the uncertainties in the link dimensions, masses, and compliance parameters. The gravity balancing begins with a simulation-based analysis of the gravitational torques of a typical serial robot. Based on the simulation results, a gravity balancing design for the robot using mechanical springs is realized. A reliability-based design optimization (RBDO) method is also developed to seek a reliable and robust design for maximized balancing performance under a prescribed uncertainty level. The RBDO is formulated with consideration of a probabilistic reliability constraint and solved by using a particle swarm optimization (PSO) algorithm. A numerical example is provided to illustrate the gravity balancing performance and reliability of a robot with uncertainties. A sensitivity analysis of the balancing design is also performed. Lastly, the effectiveness of the RBDO method is demonstrated through a case study in which the balancing performance and reliability of a robot with uncertainties are improved with the proposed method.

Co-Simulation Based Multi-Chip Module Design Flow and Wi-Fi Module Example with Integrated BAW and LNA

2017 ◽  
Vol 2017 (1) ◽  
pp. 000172-000175
Author(s):  
Jeff Dekosky ◽  
Deepukumar Nair ◽  
Larry Carastro ◽  
Scott Knapp
Keyword(s):  
Low Noise ◽  
Design Flow ◽  
Bulk Acoustic Wave ◽  
Simulation Data ◽  
Module Design ◽  
Simulation Based ◽  
Detailed Simulation ◽  
Receiver Module ◽  
Noise Amplifier ◽  
Improved Design

Abstract This paper discusses an improved design flow for hybrid Multi-Chip Modules comprising of MMICs and other components. A full 3D electromagnetic co-simulation flow is proposed. Application of such a flow is demonstrated with an MCM receiver module which has a bulk acoustic wave pre-filter, a Low Noise Amplifier with a digital bypass function, and a classical 6th order filter implemented with discrete components. Detailed simulation data is provided on each component of the system and the final MCM module, that demonstrates the use of the design flow. Finally, simulation results are compared to measured data from fabricated modules to prove the validity of our design approach

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