Particle-triggered breakdown mechanism in the presence of DC and AC electrical gradient forces in atmospheric air

1999 ◽  
Author(s):  
M. Hara
Keyword(s):  
Atmospheric Air ◽  
Breakdown Mechanism ◽  
Electrical Gradient ◽  
Gradient Forces

The development of electrical leader discharges in a point-plane gap in SF 6

1987 ◽  
Vol 412 (1843) ◽  
pp. 285-308 ◽  
Keyword(s):  
High Speed ◽  
Electrical Breakdown ◽  
Step Length ◽  
Schlieren Image ◽  
Image Converter ◽  
Time Resolved ◽  
Atmospheric Air ◽  
Air Gaps ◽  
Breakdown Mechanism ◽  
Corona Charge

Two high-speed image converter cameras and a 600 MHz digital analyser have been used to investigate electrical breakdown of SF 6 in a 20 mm point-plane gap at pressures up to 5 bar (5 × 10 5 Pa). Time-resolved records have been obtained of the schlieren image, the light emitted from the gap and the gap current during the development of impulse breakdown. It has been shown that the breakdown mechanism in a short gap in SF 6 is similar to that observed in atmospheric air gaps of several metres length. A primary corona is followed by the development of a hot leader channel which consists of a series of discrete steps. In this work it has been possible to time-resolve these steps and also to estimate the values of corona charge, leader diameter and step length. From the results obtained some insight has been gained into the mechanisms of leader formation in SF 6 .

WET BURNING – THE MODERN TREND IN ENVIRONMENTAL BENIGN FUEL COMBUSTION AND IN SOLUTION TO THE PROBLEM OF SUSTAINABLE DEVELOPMENT OF THE POWER GENERATION

2018 ◽  
pp. 96-117 ◽  
Author(s):  
B. S. Soroka
Keyword(s):  
Numerical Simulation ◽  
Nitrogen Oxides ◽  
Chemical Kinetics ◽  
Fuel Combustion ◽  
Transport Processes ◽  
Cfd Modeling ◽  
Furnace Chamber ◽  
Modern Trend ◽  
Atmospheric Air ◽  
No Formation

The article considers the role and place of water and water vapor in combustion processes with the purpose of reduction the effluents of nitrogen oxides and carbon oxide. We have carried out the complex of theoretical and computational researches on reduction of harmful nitrogen and carbon oxides by gas fuel combustion in dependence on humidity of atmospheric air by two approaches: CFD modeling with attraction of DRM 19 chemical kinetics mechanism of combustion for 19 components along with Bowman’s mechanism used as “postprocessor” to determine the [NO] concentration; different thermodynamic models of predicting the nitrogen oxides NO formation. The numerical simulation of the transport processes for momentum, mass and heat being solved simultaneously in the united equations’ system with the chemical kinetics equations in frame of GRI methane combustion mechanism and NO formation calculated afterwards as “postprocessor” allow calculating the absolute actual [CO] and [NO] concentrations in dependence on combustion operative conditions and on design of furnace facilities. Prediction in frame of thermodynamic equilibrium state for combustion products ensures only evaluation of the relative value of [NO] concentration by wet combustion the gas with humid air regarding that in case of dry air – oxidant. We have developed the methodology and have revealed the results of numerical simulation of impact of the relative humidity of atmospheric air on harmful gases formation. Range of relative air humidity under calculations of atmospheric air under impact on [NO] and [CO] concentrations at the furnace chamber exit makes φ = 0 – 100%. The results of CFD modeling have been verified both by author’s experimental data and due comparing with the trends stated in world literature. We have carried out the complex of the experimental investigations regarding atmospheric air humidification impact on flame structure and environmental characteristics at natural gas combustion with premixed flame formation in open air. The article also proposes the methodology for evaluation of the nitrogen oxides formation in dependence on moisture content of burning mixture. The results of measurements have been used for verification the calculation data. Coincidence of relative change the NO (NOx) yield due humidification the combustion air revealed by means of CFD prediction has confirmed the qualitative and the quantitative correspondence of physical and chemical kinetics mechanisms and the CFD modeling procedures with the processes to be studied. A sharp, more than an order of reduction in NO emissions and simultaneously approximately a two-fold decrease in the CO concentration during combustion of the methane-air mixture under conditions of humidification of the combustion air to a saturation state at a temperature of 325 K.

Electrical Characteristics of Atmospheric Air Corona Plasma by Multi-pin Electrodes

2019 ◽  
Vol 14 (3) ◽  
pp. 226
Author(s):  
Khanit Matra ◽  
Yottana Tanakaran ◽  
Teerawat Temponsub ◽  
Suphanat Nimbua ◽  
Phanuwat Thab-in ◽  
...  
Keyword(s):  
Electrical Characteristics ◽  
Atmospheric Air ◽  
Corona Plasma

Measurements of KrF laser-induced O2 fluorescence in high-temperature atmospheric air

1993 ◽  
Author(s):  
JAY GRINSTEAD ◽  
GABRIEL LAUFER ◽  
JAMES MCDANIEL, JR.
Keyword(s):  
High Temperature ◽  
Atmospheric Air ◽  
Krf Laser

OUTDOOR TESTS OF A TOWED BOAT MODEL WITH FUEL COMBUSTION IN A BOTTOM CAVITY

2020 ◽  
Author(s):  
S. M. FROLOV ◽  
◽  
S. V. Platonov ◽  
K. A. AVDEEV ◽  
V. S. AKSENOV ◽  
...  
Keyword(s):  
Drag Force ◽  
Direct Contact ◽  
Propulsion System ◽  
Hydrodynamic Drag ◽  
Atmospheric Air ◽  
System A ◽  
Bottom Cavity ◽  
Gas Cavity ◽  
System Power ◽  
Gas Supply

To reduce the hydrodynamic drag force to the movement of the boat, an artificial gas cavity is organized under its bottom. Such a cavity partially insulates the bottom from direct contact with water and provides “gas lubrication” by means of forced supply of atmospheric air or exhaust gases from the main propulsion system. A proper longitudinal and transverse shaping of the gas cavity can significantly (by 20%-30%) reduce the hydrodynamic drag of the boat at low (less than 3%) consumption of the propulsion system power for gas supply.

Methodical and organizational aspects in designing sanitary protection zones for a group of enterprises or industrial centers as a toll for complex atmospheric air quality assessment

2019 ◽  
pp. 940-944
Author(s):  
S. Yu. Zagorodnov ◽  
I. V. May
Keyword(s):  
Air Quality ◽  
Industrial Complex ◽  
Design Work ◽  
Atmospheric Air ◽  
Protection Zones ◽  
Industrial Enterprises ◽  
Economic Entity ◽  
Outer Border ◽  
Zone Of Influence ◽  
Environmental Measures

Introduction. Sanitary legislation of the Russian Federation provides for the organization of sanitary protection zones of industrial enterprises located in the industrial hub. However, the justification procedure, establishing and monitoring boundaries of a single sanitary zones not fully resolved. This determines the practice of organization by economic entities of individual zones separating production from residential development. This situation complicates the adequate assessment of real pollution, as well as the reasonable development of programs (plans) of environmental measures. Identification of the sources that create poor air quality and public health risks is becoming extremely problematic.The aim of the study is to develop and test recommendations for the organization and methodological support of the design of a single sanitary protection zone of a group of enterprises in the current urban development.Materials and methods. The object of the study is an industrial hub formed by 5 industrial enterprises and located on the territory of a large urban settlement with a population of more than 450 thousand people. The city administration carried out a number of organizational measures that ensured the simultaneous inventory of emissions of enterprises and the design of the general sanitary zone of the industrial complex. The design work was carried out in full accordance with the current regulatory framework.Results. The verified unified database of 102 sources of chemical emissions and 113 sources of noise provided the possibility of summary calculations and obtaining the most correct results for surface concentrations in the zone of influence of the industrial hub. The program of quality control of atmospheric air defining the contribution of each economic subject to carrying out researches is formed. This made it possible to ensure the control of all priority contaminants at the outer border of the sanitary zone and reduce the costs of each separate economic entity. Zones of responsibility of each enterprise within borders of a uniform sanitary zone for tasks of maintenance of the standard maintenance of the territory are allocated.Conclusions. The obtained results confirmed the feasibility of designing unified sanitary protection zones for economic entities located in the industrial hub.

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