Flame Stabilisation in High Velocity Gas Streams and the Effect of Heat Losses at Low Pressures

1954 ◽  
Vol 5 (4) ◽  
pp. 195-217 ◽  
Author(s):  
D. B. Spalding ◽  
B. S. Tall
Keyword(s):  
Experimental Data ◽  
High Velocity ◽  
Combustible Mixture ◽  
Heat Losses ◽  
Gas Streams ◽  
Theoretical Approaches ◽  
Theoretical Predictions ◽  
Flame Region ◽  
Low Pressures ◽  
Good Agreement

SummaryThe first object of this paper is to show the concordance between three different theoretical approaches to flame stabilisation and to compare published experimental data with the theoretical predictions. Good agreement between the theory and experimental results is obtained. The second object is to show that, at low pressures, the predictions of these theories must be qualified in view of the increasing importance of heat losses from the flame region. It is shown that there must exist a minimum pressure below which a flame cannot be maintained in a given combustible mixture, irrespective of the rate of flow of the mixture, unless heat losses are entirely eliminated.

Étude expérimentale et modélisation théorique de la décomposition du radical éthyle

1988 ◽  
Vol 66 (9) ◽  
pp. 2142-2150 ◽  
Author(s):  
Yves Simon ◽  
Jean François Foucaut ◽  
Gérard Scacchi
Keyword(s):  
Experimental Data ◽  
Rate Constants ◽  
Critical Analysis ◽  
Reaction Rate ◽  
Closed Vessel ◽  
Reaction Rate Constants ◽  
Theoretical Approaches ◽  
Lower Limits ◽  
Low Pressures ◽  
Good Agreement

A bibliographical study of the thermal decomposition of the ethyl radical shows that the kinetic parameters for the upper and lower limits of the pressure are rather scattered. This observation explains why we have carried out a new study of this elementary process in the pyrolysis of ethane, around 800 K, in a closed vessel and at pressures of the hydrocarbon varying from 1 to 300 Torr. The experimental results have been treated according to three theoretical approaches: the RRKM theory and two methods proposed by Troe. In each case, an excellent fit of the theoretical curves with the experimental data is obtained, as well as Arrhenius expressions for the reaction rate constants at high and low pressures. A detailed critical analysis of our results as well as those found in the literature shows that as yet there is no good agreement between recent studies on this subject. However, it is possible to present two Arrhenius expressions for the reaction rate constants at high and low pressures; these expressions represent a good compromise for the results obtained by various authors:[Formula: see text][Journal translation]

scholarly journals New test of the dynamic theory of neutron diffraction by a moving grating

2018 ◽  
Vol 177 ◽  
pp. 03005
Author(s):  
Maxim Zakharov ◽  
Alexander Frank ◽  
German Kulin ◽  
Semyon Goryunov
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Neutron Diffraction ◽  
Dynamic Theory ◽  
Time Of Flight ◽  
Dynamical Theory ◽  
Zero Order ◽  
Significant Suppression ◽  
Theoretical Predictions ◽  
Good Agreement

Recently, multiwave dynamical theory of neutron diffraction by a moving grating was developed. The theory predicts that at a certain height of the grating profile a significant suppression of the zero-order diffraction may occur. The experiment to confirm predictions of this theory was performed. The resulting diffracted UCNs spectra were measured using time-of-flight Fourier diffractometer. The experimental data were compared with the results of numerical simulation and were found in a good agreement with theoretical predictions.

Thermal Behavior and Friction in Journal Bearings

1970 ◽  
Vol 92 (3) ◽  
pp. 373-380 ◽  
Author(s):  
Al. Nica
Keyword(s):  
Experimental Data ◽  
Thermal Behavior ◽  
Heat Dissipation ◽  
Journal Bearings ◽  
Friction Torque ◽  
Operating Characteristics ◽  
Lubricant Flow ◽  
Theoretical Predictions ◽  
Theoretical Results ◽  
Good Agreement

This paper deals with friction and the field of temperature in the lubricant film of journal bearings. Theoretical results regarding the thermal behavior are checked with experimental data and good agreement is found. Emphasis is put on the variation of temperature and lubricant flow with the operating characteristics of the bearing and it is seen that theoretical predictions for minima of friction torque are backed by temperature measurements. Further on, the friction torque and the mechanism of heat dissipation in bearings are dealt with, in order to verify the assumptions used in the calculation schemes. The means of efficiently cooling the bearing are also discussed, as well as the part played by the divergent zone in this process.

MODELING OF GOLD DISPERSION IN GLASSY POLYMERS BY SMOLUCHOWSKI EQUATION

2002 ◽  
Vol 13 (09) ◽  
pp. 1301-1312 ◽  
Author(s):  
ZBIGNIEW J. GRZYWNA ◽  
JACEK STOLARCZYK
Keyword(s):  
Differential Equation ◽  
Experimental Data ◽  
Partial Differential Equation ◽  
Smoluchowski Equation ◽  
Glassy Polymers ◽  
Time Dependent ◽  
Acetone Vapor ◽  
Induced Stress ◽  
Theoretical Predictions ◽  
Good Agreement

A unidimensional diffusion in a potential field of induced stress is considered. The way from random walk (RW) to limiting partial differential equation (Smoluchowski equation) for standard and time dependent RW is shown. A technologically important case of gold dispersion in crystallizing polymer swollen by acetone vapor is analyzed. Theoretical predictions based on Smoluchowski equation with time dependent coefficients are found to be in very good agreement with experimental data.

The bursting of a charged cylindrical film

1972 ◽  
Vol 328 (1575) ◽  
pp. 529-539 ◽  
Keyword(s):  
Experimental Data ◽  
Finite Length ◽  
Experimental Results ◽  
Exact Calculation ◽  
Conducting Film ◽  
Half Wavelength ◽  
Theoretical Predictions ◽  
Long Cylinder ◽  
Good Agreement

This paper is a sequel to Sir Geoffrey Taylor’s study of the bursting of an electrified cylindrical conducting film. Taylor described experiments in which the voltages, at which the film becomes statically unstable, were observed for various lengths of film. These results were compared with the theoretical predictions for disturbances on an infinitely long cylinder having a wavelength equal to the length of film used. It is shown here that a transition in the mode of bursting from an axisymmetric whole wavelength mode to a lateral half wavelength mode is to be expected and that the experimental data conform with this transition. An exact calculation of the modes for a film of finite length is also given here and the resulting theoretical predictions of instability and bursting voltages are in very good agreement with the experimental results.

Reaction mechanism of the 16O + d reactions

1970 ◽  
Vol 48 (19) ◽  
pp. 2235-2253 ◽  
Author(s):  
N. E. Davison ◽  
W. K. Dawson ◽  
G. Roy ◽  
W. J. McDonald
Keyword(s):  
Experimental Data ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Direct Interaction ◽  
Scattering Data ◽  
Orbit Potential ◽  
Spectroscopic Factors ◽  
Theoretical Predictions ◽  
Using Data ◽  
Good Agreement

The reactions 16O(d,d)16O, 16O(d,p)17O, and 16O(d,n)17F have been studied in the deuteron energy range 4.00–6.00 MeV in order to determine to what extent current theories can satisfactorily describe these reactions. It was found that the theoretical curves from both the optical and DWBA models fit the experimental data significantly better when the deuteron optical-model potentials had been obtained using a spin–orbit potential in the analysis of the elastic scattering data. Spectroscopic factors obtained for the ground and first-excited states of 17O and 17F using the DWBA theory are in satisfactory agreement with theoretical predictions and with values obtained by previous workers. Small, but nonzero, spectroscopic factors have been obtained for the states at 3.058 and 3.846 MeV excitation in 17O using data measured in this work and in previous experiments. The sum of the calculated direct interaction and compound-nucleus cross sections is in good agreement with experimental data for all states studied, whether they were populated primarily by direct or compound-nucleus reactions. The calculated compound-nucleus lifetimes are also in agreement with values obtained from an analysis of the fluctuations in the yield curves.

QCD test with the momentum spectra and the second binomial moment R2 using e+e− data

2016 ◽  
Vol 94 (9) ◽  
pp. 821-825
Author(s):  
M. Hasheminia ◽  
M.E. Zomorrodian ◽  
A. Mirjalili
Keyword(s):  
Experimental Data ◽  
Center Of Mass ◽  
Coupling Constant ◽  
Monte Carlo Data ◽  
Particle Distributions ◽  
Theoretical Approaches ◽  
A Value ◽  
Momentum Spectra ◽  
200 Gev ◽  
Good Agreement

Experimental data on the shape of hadronic momentum spectra are compared to the context of calculations in modified leading log approximation (MLLA), under the assumption of local parton hadron duality (LPHD). Considered are the inclusive momentum spectra and charged particle distributions in the reaction e+e− → hadrons, using the experimental as well as the Monte Carlo data at center of mass energies up to 200 GeV. Values of the second binomial moment R2 obtained from the multiplicity distributions are also studied. Our results are compared with both experimental data from high and low energy e+e−, e−p, and pp experiments and QCD calculations in various theoretical approaches. In general, good agreement is found between the measurements and the corresponding QCD predictions. A quantitative check of LPHD + MLLA has been performed by extracting a value of the strong coupling constant from the corresponding distributions. Possible explanations for all these features will be presented in this paper.

scholarly journals On ZRP wind input term consistency in Hasselmann equation

2016 ◽  
Author(s):  
Vladimir Zakharov ◽  
Donald Resio ◽  
Andrei Pushkarev
Keyword(s):  
Experimental Data ◽  
Time Domain ◽  
Source Term ◽  
Similarity Analysis ◽  
Self Similarity ◽  
The World ◽  
Theoretical Predictions ◽  
Input Source ◽  
Wind Input ◽  
Good Agreement

Abstract. The new ZRP wind input source term (Zakharov et al., 2012) is checked for its consistency via numerical simulation of Hasselmann equation. The results are compared to field experimental data, collected at different sites around the world, and theoretical predictions of self-similarity analysis. Good agreement is obtained for limited fetch and time domain statements.

Comparison Between Theoretical Predictions of Wave Resistance and Experimental Data for the Wigley Hull

1983 ◽  
Vol 27 (04) ◽  
pp. 215-226
Author(s):  
C. Y. Chen ◽  
F. Noblesse
Keyword(s):  
Experimental Data ◽  
Froude Number ◽  
Resistance Coefficient ◽  
Wave Resistance ◽  
Number Range ◽  
Theoretical Predictions ◽  
Wigley Hull ◽  
Sinkage And Trim ◽  
Theoretical Results ◽  
Good Agreement

A number of theoretical predictions of the wave-resistance coefficient of the Wigley hull are compared with one another and with available experimental data, to which corrections for sinkage and trim are applied. The averages of eleven sets of experimental data (corrected for sinkage and trim) and of eleven sets of theoretical results for large values of the Froude number, specifically for F 0.266, 0.313, 0.350, 0.402, 0.452, and 0.482, are found to be in fairly good agreement, in spite of considerable scatter in both the experimental data and the numerical results. Furthermore, several sets of theoretical results are fairly close to the average experimental data and the average theoretical predictions for these large values of the Froude number. Discrepancies between theoretical predictions and experimental measurements for small values of the Froude number, specifically for F = 0.18, 0.20, 0.22, 0.24, and 0.266, generally are much larger than for the above-defined high-Froude-number range. However, a notable exception to this general finding is provided by the first-order slender-ship approximation evaluated in Chen and Noblesse [1],3 which is in fairly good agreement with the average experimental data over the entire range of values of Froude number considered in this study.

Dehydration of Fractal Particles of Iron (III) and Aluminum Hydroxides

1995 ◽  
Vol 407 ◽  
Author(s):  
A. A. Vertegel ◽  
S. V. Kalinin ◽  
N. N. Oleynikov ◽  
Yu. D. Tretyakov
Keyword(s):  
Experimental Data ◽  
Fractal Dimension ◽  
Metal Atom ◽  
Quantitative Model ◽  
Kinetic Behavior ◽  
Dehydration Rate ◽  
Aluminum Hydroxides ◽  
Theoretical Predictions ◽  
Fractal Particles ◽  
Good Agreement

ABSTRACTThe kinetic behavior of Fe(OH)3 and AI(OH)3 powders during thermal dehydration is investigated. It has been shown that the dehydration rate is governed by the value of fractal dimension of the sample without any respect to the nature of metal atom in hydroxide. The quantitative model for dehydration of fractal particles with particular value of fractal dimension is suggested. Theoretical predictions are in a good agreement with experimental data.

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