47,270 research outputs found
Characteristics of inhomogeneous jets in confined swirling air flows
An experimental program to study the characteristics of inhomogeneous jets in confined swirling flows to obtain detailed and accurate data for the evaluation and improvement of turbulent transport modeling for combustor flows is discussed. The work was also motivated by the need to investigate and quantify the influence of confinement and swirl on the characteristics of inhomogeneous jets. The flow facility was constructed in a simple way which allows easy interchange of different swirlers and the freedom to vary the jet Reynolds number. The velocity measurements were taken with a one color, one component DISA Model 55L laser-Doppler anemometer employing the forward scatter mode. Standard statistical methods are used to evaluate the various moments of the signals to give the flow characteristics. The present work was directed at the understanding of the velocity field. Therefore, only velocity and turbulence data of the axial and circumferential components are reported for inhomogeneous jets in confined swirling air flows
Finite Volume Cumulant Expansion in QCD-Colorless Plasma
Due to the finite size effects, the localisation of the phase transition in
finite systems and the determination of its order, become an extremely
difficult task, even in the simplest known cases. In order to identify and
locate the finite volume transition point of the QCD deconfinement
phase transition to a Colorless QGP, we have developed a new approach using the
finite size cumulant expansion of the order parameter and the -method.
The first six cumulants with the corresponding
under-normalized ratios(skewness , kurtosis ,pentosis
and hexosis ) and three unnormalized
combinations of them (, , ) are calculated and studied as functions of . A new approach,
unifying in a clear and consistent way the definitions of cumulant ratios, is
proposed. A numerical FSS analysis of the obtained results has allowed us to
locate accurately the finite volume transition point. The extracted transition
temperature value agrees with that expected from the
order parameter and the thermal susceptibility ,
according to the standard procedure of localization to within about . In
addition to this, a very good correlation factor is obtained proving the
validity of our cumulants method. The agreement of our results with those
obtained by means of other models is remarkable.Comment: 19 pages,14 figues, figures 4,5,6 figures are oversized, therefore,
can be obtained directly from [email protected],Accepted for publication in
EPJ
A study of the Haor areas of Sylhet-Mymensing districts with ERTS imageries (winter crop estimation)
There are no author-identified significant results in this report
Behavior of turbulent gas jets in an axisymmetric confinement
The understanding of the mixing of confined turbulent jets of different densities with air is of great importance to many industrial applications, such as gas turbine and Ramjet combustors. Although there have been numerous studies on the characteristics of free gas jets, little is known of the behavior of gas jets in a confinement. The jet, with a diameter of 8.73 mm, is aligned concentrically in a tube of 125 mm diameter, thus giving a confinement ratio of approximately 205. The arrangement forms part of the test section of an open-jet wind tunnel. Experiments are carried out with carbon dioxide, air and helium/air jets at different jet velocities. Mean velocity and turbulence measurements are made with a one-color, one-component laser Doppler velocimeter operating in the forward scatter mode. Measurements show that the jets are highly dissipative. Consequently, equilibrium jet characteristics similar to those found in free air jets are observed in the first two diameters downstream of the jet. These results are independent of the fluid densities and velocities. Decay of the jet, on the other hand, is a function of both the jet fluid density and momentum. In all the cases studied, the jet is found to be completely dissipated in approximately 30 jet diameters, thus giving rise to a uniform flow with a very high but constant turbulence field across the confinement
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