ON FLAME PROPAGATION IN EXPLOSIVE MIXTURES OF GASES: III. FLAME PROPAGATION IN MIXTURES OF METHANE AND NITROGEN AIR, HELIUM AIR, AND ARGON AIR

1956 ◽  
Vol 34 (3) ◽  
pp. 331-337 ◽  
Author(s):  
Robert Sandri
Keyword(s):  
Temperature Distribution ◽  
General Theory ◽  
Oxygen Atom ◽  
Flame Propagation ◽  
Flame Velocity ◽  
Flame Zone ◽  
End Products ◽  
Atom Chain ◽  
Experimental Values ◽  
Good Agreement

The general theory developed in an earlier paper of the author is applied to the combustion of mixtures of methane and nitrogen air, helium air, and argon air where dissociation of the end products is negligible. The oxygen atom chain is assumed to be rate-determining. Absolute values of the flame velocity are computed for mixtures containing 8% of methane and for the stoichiometric mixtures. The results are found to be in very good agreement with experimental values. Dependence on pressure is likewise found to be in very good agreement with experiments. The temperature distribution in the flame zone is also computed.

ON FLAME PROPAGATION IN EXPLOSIVE MIXTURES OF GASES: I. GENERAL THEORY

1956 ◽  
Vol 34 (3) ◽  
pp. 313-323 ◽  
Author(s):  
Robert Sandri
Keyword(s):  
Temperature Distribution ◽  
Flame Propagation ◽  
Energy Equation ◽  
Approximation Formula ◽  
Flame Velocity ◽  
System Of Differential Equations ◽  
Flame Zone ◽  
Method Of Solution ◽  
Set Up ◽  
Numerical Method Of Solution

The system of differential equations of flame propagation is set up and discussed. It is shown that, without any major influences being neglected, the energy equation can be reduced to the form[Formula: see text]with the boundary conditions[Formula: see text]Some qualities of the solutions of this equation are discussed and a simple numerical method of solution is described. The flame velocity V0 is found as an eigenvalue of the energy equation. The temperature distribution in the flame zone can then be found by an ordinary quadrature. Further, an approximation formula for finding V0 directly is derived[Formula: see text]where F(η) is proportional to [Formula: see text]and has a maximum for η = ηm.

ON FLAME PROPAGATION IN EXPLOSIVE MIXTURES OF GASES: II. ON THE DECOMPOSITION FLAME OF OZONE

1956 ◽  
Vol 34 (3) ◽  
pp. 324-330 ◽  
Author(s):  
Robert Sandri
Keyword(s):  
Diffusion Coefficient ◽  
General Theory ◽  
Numerical Integration ◽  
Flame Propagation ◽  
Approximation Method ◽  
Flame Velocity ◽  
Good Agreement

The general theory developed in an earlier paper of the author is applied to the ozone explosion. Values of the linear flame velocity are computed under the assumption of constant enthalpy and, without this assumption, for different values of the reduced diffusion coefficient. The results do not differ very much and are found to be in very good agreement with experiments. They are further compared to the results which were obtained by Hirschfelder et al. by exact numerical integration and by Kármán and Penner by an approximation method and are found to be between the values obtained by these authors.

An Investigation on Temperature Distribution and Cooling Rate of ERW Pipes during TIG Welding

2014 ◽  
Vol 14 (4) ◽  
pp. 219-231 ◽  
Author(s):  
Tathagata Bhattacharya ◽  
Asish Bandyopadhyay ◽  
Pradip Kumar Pal
Keyword(s):  
Temperature Distribution ◽  
External Surface ◽  
Tig Welding ◽  
Point Heat Source ◽  
Pipe Surface ◽  
Two Samples ◽  
Experimental Values ◽  
Different Diameters ◽  
Good Agreement

AbstractThe present investigation deals with the determination of temperature profile and subsequent rates of cooling at certain points on the external surface along axis of an ERW pipe, during TIG welding. Two samples of different diameters of pipes of ASTM A 106 Gr. B, seamless type are selected for experimentation. The temperatures on the external surface at different locations on each of these seamless pipes (of different diameters) during welding have been measured with the help of digital pyrometers. The temperature variation along the axis of pipe from the weld arc has been presented. Thereafter, through separate analytical methods the temperature distribution across the external surface of the pipe for a given point heat source is theoretically calculated, and the results are compared with the previously found experimental values of temperatures. They are found to be well in agreement. Further, the rates of cooling of a pre-selected point on the pipe surface are experimentally and analytically determined under varying welding conditions and are compared likewise and are found to be in good agreement too.

Ignition and Flame Propagation in Oxy-Methane Mixtures Diluted With CO2

2015 ◽  
Author(s):  
Bader Almansour ◽  
Luke Thompson ◽  
Joseph Lopez ◽  
Ghazal Barari ◽  
Subith S. Vasu
Keyword(s):  
Flame Propagation ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Dynamic Pressure ◽  
Burning Velocity ◽  
Reaction Rates ◽  
Current Data ◽  
Initiation And Propagation ◽  
Experimental Values ◽  
Good Agreement

Ignition and flame propagation in methane/O2 mixtures diluted with CO2 are studied. A laser ignition system and dynamic pressure data are utilized to ignite the mixture and to record the combustion pressure, respectively. The laminar burning velocities (LBV) are obtained at room temperature and atmospheric pressure in a spherical combustion chamber. Flame initiation and propagation is recorded by using a high-speed camera in select experiments to visualize the effect of CO2 proportionality on the combustion behavior. The laminar burning velocity is studied for a range of equivalence ratios (ϕ =0.8–1.3, in steps of 0.1), and oxygen ratios, D=O2/(O2+CO2) (26–38% by volume). It was found that the LBV decreases by increasing the CO2 proportionality. It was observed that the flame propagates toward the laser at a faster rate as the CO2 proportionality increases. Current experiments are in very good agreement with existing literature data. The premixed flame model from CHEMKIN PRO [1] software and two mechanisms (GRI-Mech 3.0 [2] and ARAMCO Mech 1.3 [3]) are used to simulate the current data. In general, simulations are in reasonable agreement with current data though the mechanisms predict slower flame speeds. The LBV values obtained by the ARAMCO 1.3 mechanism are closer to the experimental values. Additionally, sensitivity analysis is carried out to understand the important reactions that influence the predicted flame speeds. Improvements to the GRI predictions are suggested after incorporating latest reaction rates from literature for key reactions.

ON FLAME PROPAGATION IN EXPLOSIVE MIXTURES OF GASES: IV. ON THE DECOMPOSITION FLAME OF OZONE IN MIXTURES RICH IN OZONE

1957 ◽  
Vol 35 (5) ◽  
pp. 474-476 ◽  
Author(s):  
Robert Sandri
Keyword(s):  
Flame Propagation ◽  
Atomic Oxygen ◽  
High Concentration ◽  
Experimental Values ◽  
Good Agreement

The theory of flame propagation in ozone–oxygen mixtures developed in earlier papers of the author is applied to mixtures containing 50%–100% ozone. The formulae are modified to allow for comparatively high concentration of atomic oxygen. The results are found to be in very good agreement with experimental values which have recently become available.

Systematic calculations of energy levels and transitions rates in Mo XXVIII

2020 ◽  
Vol 75 (8) ◽  
pp. 739-747
Author(s):  
Feng Hu ◽  
Yan Sun ◽  
Maofei Mei
Keyword(s):  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Data Sets ◽  
Electron Systems ◽  
Excitation Energies ◽  
Experimental Values ◽  
Qed Effects ◽  
Hyperfine Structures ◽  
Good Agreement

AbstractComplete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors and E1, E2, M1, and M2 line strengths, oscillator strengths, transitions rates are reported for the low-lying 41 levels of Mo XXVIII, belonging to the n = 3 states (1s22s22p6)3s23p3, 3s3p4, and 3s23p23d. High-accuracy calculations have been performed as benchmarks in the request for accurate treatments of relativity, electron correlation, and quantum electrodynamic (QED) effects in multi-valence-electron systems. Comparisons are made between the present two data sets, as well as with the experimental results and the experimentally compiled energy values of the National Institute for Standards and Technology wherever available. The calculated values including core-valence correction are found to be in a good agreement with other theoretical and experimental values. The present results are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing plasmas.

scholarly journals Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1622
Author(s):  
Wipawee Tepnatim ◽  
Witchuda Daud ◽  
Pitiya Kamonpatana
Keyword(s):  
Temperature Distribution ◽  
Electric Field ◽  
Three Dimensional ◽  
Development Stage ◽  
Microwave Oven ◽  
Computational Time ◽  
Plastic Package ◽  
Heating Uniformity ◽  
The Cost ◽  
Good Agreement

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

Finite element method estimation of temperature distribution of automotive tire using one-way-coupled method

2021 ◽  
pp. 095440702110087
Author(s):  
Zumrat Usmanova ◽  
Emin Sunbuloglu
Keyword(s):  
Thermal Analysis ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Complex Geometry ◽  
Rolling Resistance ◽  
Operating Conditions ◽  
Deformation Analysis ◽  
Coupled Method ◽  
Experimental Values ◽  
Hysteretic Loss

Numerical simulation of automotive tires is still a challenging problem due to their complex geometry and structures, as well as the non-uniform loading and operating conditions. Hysteretic loss and rolling resistance are the most crucial features of tire design for engineers. A decoupled numerical model was proposed to predict hysteretic loss and temperature distribution in a tire, however temperature dependent material properties being utilized only during the heat generation analysis stage. Cyclic change of strain energy values was extracted from 3-D deformation analysis, which was further used in a thermal analysis as input to predict temperature distribution and thermal heat generation due to hysteretic loss. This method was compared with the decoupled model where temperature dependence was ignored in both deformation and thermal analysis stages. Deformation analysis results were compared with experimental data available. The proposed method of numerical modeling was quite accurate and results were found to be close to the actual tire behavior. It was shown that one-way-coupled method provides rolling resistance and peak temperature values that are in agreement with experimental values as well.

scholarly journals DFT calculation and assignment of vibrational spectra of aryl and alkyl chlorophosphates

2014 ◽  
Vol 12 (2) ◽  
pp. 153-163
Author(s):  
Viktor Anishchenko ◽  
Vladimir Rybachenko ◽  
Konstantin Chotiy ◽  
Andrey Redko
Keyword(s):  
Vibrational Spectra ◽  
Basis Sets ◽  
Heavy Atoms ◽  
Wide Range ◽  
Complete Assignment ◽  
Key Factor ◽  
Polarization Functions ◽  
Experimental Values ◽  
Semi Empirical ◽  
Good Agreement

AbstractDFT calculations of vibrational spectra of chlorophosphates using wide range of basis sets and hybrid functionals were performed. Good agreement between calculated and experimental vibrational spectra was reached by the combination of non-empirical functional PBE0 with both middle and large basis sets. The frequencies of the stretching vibrations of the phosphate group calculated using semi-empirical functional B3LYP for all basis sets deviate significantly from the experimental values. The number of polarization functions on heavy atoms was shown to be a key factor for the calculation of vibrational frequencies of organophosphates. The importance of consideration of all the stable rotamers for a complete assignment of fundamental modes was shown.

scholarly journals Structural elastic and thermal properties of SrxCd1−x O mixed compounds — a theoretical approach

2014 ◽  
Vol 32 (3) ◽  
pp. 350-357
Author(s):  
Purvee Bhardwaj
Keyword(s):  
Phase Transition ◽  
Vibrational Energy ◽  
Zero Point ◽  
Study Phase ◽  
Energy Effect ◽  
Phase Transition Pressure ◽  
Vegard’S Law ◽  
Extended Interaction ◽  
Experimental Values ◽  
Good Agreement

AbstractIn the present paper, the structural and mechanical properties of alkaline earth oxides mixed compound SrxCd1−x O (0 ≤ x ≤ 1) under high pressure have been reported. An extended interaction potential (EIP) model, including the zero point vibrational energy effect, has been developed for this study. Phase transition pressures are associated with a sudden collapse in volume. Phase transition pressure and associated volume collapses [ΔV (Pt)/V(0)] calculated from this approach are in good agreement with the experimental values for the parent compounds (x = 0 and x = 1). The results for the mixed crystal counterparts are also in fair agreement with experimental data generated from the application of Vegard’s law to the data for the parent compounds.

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