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1
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New closure method for a simultaneous diazo coupling between 1- and 2-Naphthols and diazotized sulphanilic acid

100%
Bałdyga J., Jasińska M.
Polish Journal of Chemical Technology
|
2009
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vol. 11
|
issue 2
1-5
EN
This paper presents the effects of mixing on the course of complex chemical reactions in relation to the manufacturing of pure products at high reaction selectivity, and designing mixing strategies using complex, homogeneous test reaction systems. As an example, the competitive-consecutive and parallel reaction test system including a simultaneous diazo-coupling between 1- and 2-naphtols and diazotized sulphanilic acid is considered. The effect of mixing on the reaction selectivity is interpreted using mechanistic modeling and a new closure scheme. The new closure represents an extension of the conditional PDF closure applied before to simple reaction schemes.
2
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The structure of average turbulent flow field

100%
Heinloo J.
Open Physics
|
2010
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vol. 8
|
issue 1
17-24
EN
A mathematical formalism to reflect the turbulent hierarchic eddy structure in an average turbulence description is discussed. The formalism is founded on simultaneous application of turbulent flow field splitting procedures by the motion variability and by the motion order explained in the paper. It is shown that this formalism permits the outlining of different types of cascading processes in turbulent media within the turbulence average description.
3
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Analysis of the fluctuations of a laser beam due to thermal turbulence

100%
Ndlovu S., Chetty N.
Open Physics
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2014
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vol. 12
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issue 7
466-472
EN
A laser beam propagating in air and passing through a point diffraction interferometer (PDI) produces stable interferograms that can be used to extract wavefront data such as major atmospheric characteristics: turbulence strength, inner scale and outer scale of the refractive index. These parameters need to be taken into consideration when developing defense laser weapons since they can be affected by thermal fluctuations that are due to the changes in temperature in close proximity to the propagating beam and results in phase shifts that can be used to calculate the temperature which causes wavefront perturbations on a propagating beam.
4
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Characteristics of the flow field in the combustion chamber of the internal combustion test engine

100%
Tutak W., Jamrozik A.
Chemical and Process Engineering
|
2011
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vol. 32
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issue 3
203-214
EN
Results of a research study into the velocity field in combustion chamber of internal combustion engine are presented in the paper. Measurements of fresh charge flow velocity in the cylinder axis and near the cylinder squeezing surface were performed. The hot-wire anemometer was used. The measurement results were used for analysis of turbulence field in the examined combustion chamber. It turned out that in the axis of cylinder the maximum of velocity occurs 30 deg before TDC and achieves 6 m/s. In the studied combustion chamber, the maximum value of turbulence intensity was close to 0.2 and it was achieved 35 deg BTDC. Additionally, the maximal velocity dispersion in the following cycles of the researched engine was at the level of 2 m/s, which is 35% of the maximum value of flow velocity. At a point located near the squeezing surface of the piston, a similar level of turbulence, but a the smaller value of the average velocity was achieved. The turbulence field turned out to be inhomogeneous in the combustion chamber.
5
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The use of Lempel-Ziv complexity to analyze turbulence and flow randomness based on velocity fluctuations

88%
Blonski S., Pregowska A., Michalek T., Szczepanski J.
|
2019
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issue 5
6
Publication available in full text mode
Content available

Characteristics of the flow field in the combustion chamber of the internal combustion test engine

88%
Tutak W., Jamrozik A.
Chemical and Process Engineering
|
2011
|
issue 3
7
Content available remote

Modelling of a passive autocatalytic hydrogen recombiner – a parametric study

88%
Rożeń A.
|
|
issue 1
161-169
EN
Operation of a passive autocatalytic hydrogen recombiner (PAR) has been investigated by means of computational fluid dynamics methods (CFD). The recombiner is a self-active and self-adaptive device used to remove hydrogen from safety containments of light water nuclear reactors (LWR) by means of a highly exothermic reaction with oxygen at the surface of a platinum or palladium catalyst. Different turbulence models (k-ω, k-ɛ, intermittency, RSM) were applied in numerical simulations of: gas flow, heat and mass transport and chemical surface reactions occurring in PAR. Turbulence was found to improve mixing and mass transfer and increase hydrogen recombination rate for high gas flow rates. At low gas flow rates, simulation results converged to those obtained for the limiting case of laminar flow. The large eddy simulation technique (LES) was used to select the best RANS (Reynolds average stress) model. Comparison of simulation results obtained for two- and three-dimensional computational grids showed that heat and mass transfer occurring in PAR were virtually two-dimensional processes. The effect of hydrogen thermal diffusion was also discussed in the context of possible hydrogen ignition inside the recombiner.
8
Content available remote

Transverse electron focusing as a way of studying phonon kinetics. Turbulence of phonon flow

51%
Tsoi V.
Open Physics
|
2003
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vol. 1
|
issue 1
72-90
EN
Novel techniques have been created for studying phonon kinetics. A supersonic conduction electron flux is used to produce a phonon flux. Transverse electron focusing (TEF) is applied for checking the electron gas affected by phonons. A turbulent regime of phonon flow-phonon flux step broadening-reveals itself as step broadening of non-equilibrium electron flux.
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