Effects of Gas Radiation on Thermal Performances of Single and Double Flow Plane Solar Heaters

In this work is studying temperature influence and surface anchoring in orientation behaviour of oscillatory Poiseuille flow of nematic liquid crystal (NLC) in the plane cell. Without external influence molecules lays along flow plane. Molecules orientation change and caused by this back-flow is studied by low-amplitude decomposition.

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Effect of combined natural convection and non-gray gas radiation on entropy generation through a cylindrical annulus

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-021-10669-7 ◽

2021 ◽

Author(s):

K. Jarray ◽

A. Mazgar ◽

F. Ben Nejma

Keyword(s):

Natural Convection ◽

Entropy Generation ◽

Gas Radiation ◽

Cylindrical Annulus

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Gas-ionizing shocks in a magnetic field

Journal of Plasma Physics ◽

10.1017/s0022377800003081 ◽

1967 ◽

Vol 1 (1) ◽

pp. 37-54 ◽

Cited By ~ 13

Author(s):

M. D. Cowley

Keyword(s):

Magnetic Field ◽

Electric Field ◽

Wave Speed ◽

Normal Velocity ◽

Electrically Conducting ◽

Shock Stability ◽

The Face ◽

Arbitrary Velocity ◽

Flow Plane ◽

The Magnetic Field

Ionizing shocks for plane flows with the magnetic field lying in the flow plane are considered. The gas is assumed to be electrically conducting downstream, but non-conducting upstream. Shocks whose downstream state has a normal velocity component less than the slow magneto-acoustic-wave speed and whose upstream state is supersonic are found to be non-evolutionary in the face of plane magneto-acoustic disturbances, unless the upstream electric field in a frame of reference where the gas is at rest is arbitrary. Velocity conditions are also determined for shock stability with the electric field not arbitrary.Shock structures are found for the case of large ohmic diffusion, the initial temperature rise and ionization of the gas being caused by a thin transition having the properties of an ordinary gasdynamic shock. For the case where shocks are evolutionary when the upstream electric field is arbitrary, the shock structure requirements only restrict the electric field by limiting the range of possible values. When shocks are evolutionary with the electric field not arbitrary, they can only have a structure for a particular value of the electric field. Limits to the current carried by ionizing shocks and the effects of precursor ionization are discussed qualitatively.

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Calculation of Radiation Signal of Rocket Plume after Atmospheric Attenuation Using Wide Band K-Distribution Model

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.295-298.2437 ◽

2013 ◽

Vol 295-298 ◽

pp. 2437-2441

Author(s):

Xue Mei Yin ◽

Qiu Yang Ma ◽

Xue Hong Wu ◽

Yi Gong ◽

Yan Li Lu

Keyword(s):

Remote Sensing ◽

Rocket Engine ◽

Wide Band ◽

Distribution Model ◽

Climatic Effects ◽

Radiation Process ◽

Gas Radiation ◽

Atmospheric Remote Sensing ◽

Rocket Plume ◽

Liquid Rocket

The calculation of the gas radiation process plays an important role in the study of atmospheric remote sensing and climatic effects of greenhouse gas. The remote sensing of rocket plume has important significance for early warning, interception, detection, identification and tracking of flight vehicle. A model was established to calculate the remote sensing signal of rocket plume by wide band k-distribution, the liquid rocket plume remote sensing signals in atmospheric window region and the detectors’ working spectrum are calculated, and the results were compared with the results calculated by line-by-line approach. The results showed that in some of the detectors’ working spectral regions, the wide band k-distribution model can be used for the calculation of the remote sensing of liquid rocket engine exhaust plume.

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Streamwise evolution of longitudinal vortices in a turbulent boundary layer

Journal of Fluid Mechanics ◽

10.1017/s0022112008004825 ◽

2009 ◽

Vol 623 ◽

pp. 27-58 ◽

Cited By ~ 35

Author(s):

OLA LÖGDBERG ◽

JENS H. M. FRANSSON ◽

P. HENRIK ALFREDSSON

Keyword(s):

Boundary Layer ◽

Turbulent Boundary Layer ◽

Vortex Core ◽

Cross Flow ◽

General Point ◽

Natural Setting ◽

Viscous Effects ◽

Array Configuration ◽

The Cross ◽

Flow Plane

In this experimental study both smoke visualization and three-component hot-wire measurements have been performed in order to characterize the streamwise evolution of longitudinal counter-rotating vortices in a turbulent boundary layer. The vortices were generated by means of vortex generators (VGs) in different configurations. Both single pairs and arrays in a natural setting as well as in yaw have been considered. Moreover three different vortex blade heights h, with the spacing d and the distance to the neighbouring vortex pair D for the array configuration, were studied keeping the same d/h and D/h ratios. It is shown that the vortex core paths scale with h in the streamwise direction and with D and h in the spanwise and wall-normal directions, respectively. A new peculiar ‘hooklike’ vortex core motion, seen in the cross-flow plane, has been identified in the far region, starting around 200h and 50h for the pair and the array configuration, respectively. This behaviour is explained in the paper. Furthermore the experimental data indicate that the vortex paths asymptote to a prescribed location in the cross-flow plane, which first was stated as a hypothesis and later verified. This observation goes against previously reported numerical results based on inviscid theory. An account for the important viscous effects is taken in a pseudo-viscous vortex model which is able to capture the streamwise core evolution throughout the measurement region down to 450h. Finally, the effect of yawing is reported, and it is shown that spanwise-averaged quantities such as the shape factor and the circulation are hardly perceptible. However, the evolution of the vortex cores are different both between the pair and the array configuration and in the natural setting versus the case with yaw. From a general point of view the present paper reports on fundamental results concerning the vortex evolution in a fully developed turbulent boundary layer.

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Some Remarks on the Behaviour of Surface Source Distributions near the Edge of a Body

Aeronautical Quarterly ◽

10.1017/s0001925900006387 ◽

1973 ◽

Vol 24 (1) ◽

pp. 25-33

Author(s):

J W Craggs ◽

K W Mangler ◽

M Zamir

Keyword(s):

Flow Direction ◽

Three Dimensional ◽

Cross Flow ◽

Symmetric Case ◽

The Body ◽

Dimensional Problem ◽

Surface Source ◽

Asymmetric Case ◽

Main Flow Direction ◽

Flow Plane

SummaryWhen the incompressible potential flow past a three-dimensional body is represented by source distributions on the body surface, these source distributions have singularities near an edge or corner, for example á trailing edge of a wing or the (unfaired) intersection of a body and a wing. The nature of these singularities is discussed. When assuming slow variations of the geometry in the main flow direction we can consider a two-dimensional problem in the cross-flow plane. Here the tangential velocities and source distributions are proportional to certain powers of the distance from the corner. For example at a convex right-angled corner these powers are − ⅓ in the asymmetric case (the bisector is a potential line) and ⅓ in the symmetric case (the bisector is a streamline) for both sources and tangential velocities. At a concave right-angled corner the corresponding values for the source distributions are ⅓ (asymmetric case) and − ⅓ (symmetric case) whereas they are 1 and 3 respectively for the tangential velocities.

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