Evaluation of Road Subsidence Risk from Model Chamber Tests

2019 ◽  
Vol 21 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Gichul Kweon ◽  
Seokil Choi
Keyword(s):  
Model Chamber

scholarly journals Investigation of the Arc Characteristics of Switching DC Arcs on Hydrogen Containing Gas Mixtures

2019 ◽  
Vol 6 (1) ◽  
pp. 69-72 ◽  
Author(s):  
D. Gonzalez ◽  
S. Gortschakow ◽  
S. Yu ◽  
F. Werner
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
High Speed ◽  
Gas Mixtures ◽  
High Speed Imaging ◽  
Arc Characteristics ◽  
Pressure Discharge ◽  
Model Chamber ◽  
Imaging And Spectroscopy ◽  
Dc Current

<p>The characteristics of switching DC current arcs in  hydrogen  containing gas mixtures under pressure were investigated using a model chamber. The switching device consists of an electro-mechanic double breaker unit with copper contacts. High-speed imaging and spectroscopy were used to observe and to characterize the switching arc. The experiments indicate how the dynamic interaction of an external magnetic field with a high-pressure discharge causes an elongation and twisting of the arc-channel and consequently a voltage increase. Comparative measurements with and without external magnetic field indicate a strong influence of this factor. Cu and N lines together with strongly broadened H lines were observed.</p>

Time-Resolved Analysis of SF6 Arc Plasmas in a Laboratory Model Chamber for Circuit Breaker

2020 ◽  
Vol 48 (11) ◽  
pp. 3968-3974
Author(s):  
Sungbin Park ◽  
Donghee Kim ◽  
Yoosung Kim ◽  
Seunggi Ham ◽  
Jonghyeon Ryu ◽  
...  
Keyword(s):  
Circuit Breaker ◽  
Laboratory Model ◽  
Time Resolved ◽  
Model Chamber ◽  
Arc Plasmas

scholarly journals Investigation of an Ablation-dominated Arc in a Model Chamber by Optical Emission Spectroscopy

2017 ◽  
Vol 4 (2) ◽  
pp. 153-156 ◽  
Author(s):  
R. Methling ◽  
A. Khakpour ◽  
S. Wetzeler ◽  
D. Uhrlandt
Keyword(s):  
Emission Spectroscopy ◽  
High Speed ◽  
Optical Emission Spectroscopy ◽  
Rotational Symmetry ◽  
Line Emission ◽  
Optical Emission ◽  
Ambient Air ◽  
Video Camera ◽  
Radial Temperature ◽  
Model Chamber

A switching arc in a model chamber is investigated by means of optical emission spectroscopy. Ignition wire is applied to initiate an arc of several kiloampere between tungsten−copper electrodes. Radiation emitted by the arc plasma is absorbed by a surrounding PTFE nozzle, leading to an ablation–dominated discharge. Video spectroscopy is carried out using an imaging spectrometer combined with a high–speed video camera. Carbon ion and fluorine atom line emission from the heating channel as well as copper, oxygen and nitrogen from ignition wire and ambient air are analyzed with focus on the low–current phases at the beginning of discharge and near current zero. Additionally, electrical parameters and total pressure are recorded while the general behavior of the discharge is observed by another video camera. Considering rotational symmetry of the arc the corresponding radial emission coefficients are determined. Finally, radial temperature profiles are calculated.

Effects of Burner Interaction on NOx Emission From Swirl Premix Burner in a Gas Turbine Combustor

2014 ◽  
Author(s):  
Cheon Hyeon Cho ◽  
Chae Hoon Sohn ◽  
Ju Hyeong Cho ◽  
Han Seok Kim
Keyword(s):  
Gas Turbine ◽  
Nox Emission ◽  
Gas Turbine Combustor ◽  
Step Size ◽  
Flow Temperature ◽  
Nox Formation ◽  
Air Stream ◽  
Flow Interactions ◽  
Model Chamber ◽  
Wall Interaction

Flame interaction between neighboring burners in a gas turbine combustor is investigated numerically for pursuit of its effect on NOx emission from the burners. In a model chamber or liner, EV burners with double cone are installed. Two burners with the same rotating direction of air stream are adopted and the distance between them is variable from 74.2 mm to 222.6 mm by the step size of 37.1 mm. Gaseous methane and air are adopted as fuel and oxidizer, respectively. From steady-state numerical analyses, flow, temperature, and NO concentration fields are calculated in all computational cases to find their correlation with NOx formation. NOx emission is evaluated at the exit of the model chamber with two burners as a function of burner distance and compared with that from a single burner. In all cases of two-burner calculations, NOx emission is higher than that of a single burner, which results from flow interactions between neighboring burners as well as between a burner and a liner wall. NOx emission is affected significantly by flow and flame interactions between them and strongly depends on burner distance. Burner interaction is divided into two regimes of a burner-burner interaction and a burner-wall interaction depending on the distance. In the former regime, NOx emission is reduced as flame interaction between burners is enhanced and in the latter regime, it is also reduced as interaction between the burner and the liner wall is enhanced.

Preparation and Characterization of Nanocrystalline CaO-ZrO2 Powders by Microwave Pyrolysis

2014 ◽  
Vol 602-603 ◽  
pp. 97-100
Author(s):  
Bing Bing Fan ◽  
Ke Ke Guan ◽  
Hao Chen ◽  
Xiao Xuan Pian ◽  
Chen Yang Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Reaction Temperature ◽  
Pyrolysis Temperature ◽  
Precipitation Method ◽  
Microwave Pyrolysis ◽  
Model Chamber ◽  
Co Precipitation ◽  
Average Size

CaO(15%)-ZrO2nano-powders were prepared by microwave pyrolysis in a multi-model chamber at the temperature ranging from 650°C to 800°C, with the precursor processed at different reaction temperature from 0°C to 80°C by chemical co-precipitation method. XRD and SEM techniques were used to characterize the phase transition and micrograph of powders. It is found that the content of m-ZrO2phase decreased with the increasing of reaction temperature and pyrolysis temperature. The high dispersed and superfine nano-powders were obtained at the pyrolysis temperature of 750°C for 20 min at 80°C. And only cubic ZrO2phase were detected in CaO (15%)-ZrO2powders and the average size of the powders is about 41 nm.

Influence of stream swirling on heat transfer in the cylindrical section of the prenozzle volume of a model chamber

1979 ◽  
Vol 37 (4) ◽  
pp. 1141-1145
Author(s):  
F. I. Sharafutdinov ◽  
A. I. Mironov ◽  
V. K. Shchukin
Keyword(s):  
Heat Transfer ◽  
Cylindrical Section ◽  
Model Chamber

scholarly journals Detection of Cavities Beneath Plate Structure using a Microphone

2020 ◽  
Vol 20 (6) ◽  
pp. 229-237
Author(s):  
Seonghun Kang ◽  
Jong-Sub Lee ◽  
Jung-Doung Yu ◽  
Sang Yeob Kim
Keyword(s):  
Flexural Vibration ◽  
Signal Amplitude ◽  
Laboratory Model ◽  
Sound Waves ◽  
Plate Structures ◽  
Plate Structure ◽  
Acrylic Plate ◽  
Model Chamber ◽  
Dry Soil ◽  
Measurement Location

Failure of plate structures such as pavements can be caused by the occurrence of cavities beneath the structure. In this study, a cavity beneath the plate structure were detected in a laboratory model chamber using a hammer and microphone. Specifically, a chamber was constructed using an acrylic plate and dry soil to simulate the pavement and the subgrade, respectively. A plastic box was placed between the acrylic plate and dry soil to simulate a cavity beneath the pavement. The sound waves generated by impacting the acrylic plate with a hammer were measured using a microphone. The measured area under the rectified signal envelope (MARSE) energy was calculated for the measured sound waves, and the variation in it were analyzed according to the measurement location. The test results show that the signal attenuation was low at the cavity section owing to the conservation of impact energy and that the signal amplitude becomes lower at the soil section owing to the weakened flexural vibration. Therefore, the estimated MARSE energy at the cavity section was larger than that at the soil section. This study demonstrates the effective utilization of microphones for detecting cavities beneath the plate structures.

scholarly journals Investigation on Acoustic Properties of Thruster Chamber with Coaxial Injectors and Plenum Chamber

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Dekun Gao ◽  
Jianxiu Qin ◽  
Huiqiang Zhang
Keyword(s):  
Acoustic Pressure ◽  
Rocket Engine ◽  
Pressure Oscillation ◽  
Acoustic Mode ◽  
Acoustic Properties ◽  
Pressure Oscillations ◽  
Plenum Chamber ◽  
Model Chamber ◽  
Pressure Peak ◽  
Tuning Frequency

Based on the URANS equation, a numerical simulation is carried out for acoustic properties of the thruster chamber with coaxial injectors and plenum chamber in a liquid rocket engine. Pressure oscillations with multiacoustic modes are successfully excited in the chamber by using the constant volume bomb method. FFT analysis is applied to obtain the acoustic properties of eigenfrequencies, power amplitudes, and damping rates for each excited acoustic mode. Compared with the acoustic properties in the model chamber with and without an injector as well as with and without the plenum chamber, it can be found that the injector with one open end and one half-open end still can work as a quarter-wave resonator. The power amplitudes of the acoustic mode can be suppressed significantly when its eigenfrequency is close to the tuning frequency of the injector, which is achieved by Cutting down the pressure Peak and Raising up the pressure Trough (CPRT). Compared with the acoustic properties in the model chamber with and without the plenum chamber, it can be found that 1L acoustic pressure oscillation is inhibited completely by the plenum chamber and other acoustic pressure oscillations are also suppressed in a different extent. The injector and plenum chamber have a little effect on the eigenfrequencies and damping rate of each acoustic mode. For multimode pressure oscillation, it is better for tuning frequency of the injector closing to the lower eigenfrequency acoustic mode, which will be effective for suppression of these multiacoustic modes simultaneously.

High-temperature effect of a gas jet of reactants on the front plate

2021 ◽  
Author(s):  
S.V. Mosolov ◽  
I.S. Partola ◽  
A.S. Kudinov ◽  
I.I. Yurchenko ◽  
A.G. Klimenko ◽  
...  
Keyword(s):  
High Temperature ◽  
Near Field ◽  
Gas Jet ◽  
Jet Flows ◽  
Software Systems ◽  
Stagnation Temperature ◽  
Frontal Surface ◽  
Front Plate ◽  
Reacting Mixtures ◽  
Model Chamber

The paper introduces the results of measuring and predicting the heat and force effect of jets of high-temperature reacting mixtures on the oxygen-methane, oxygen-alcohol components when acting on the front plate in the near field of the jet. A high-temperature supersonic gas jet flows out of a model chamber with a Laval nozzle into a medium with atmospheric pressure at a degree of off-design ratio of about unity. In the chamber, ignition and stable combustion of a mixture of selected substances occur, the ratio of these substances providing a stagnation temperature in the range of 1900 ... 3400 K. The pressure distribution function on the front plate obtained in the experiment is used. The proposed model of the high-temperature flow effect on the frontal surface can be used to test software systems and determine the levels of thermal effect during sample tests.

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