Laser-Doppler Measurements of Velocities Just Downstream of a Collapsible Tube During Flow-Induced Oscillations

2001 ◽  
Vol 123 (5) ◽  
pp. 493-499 ◽  
Author(s):  
C. D. Bertram ◽  
G. Diaz de Tuesta ◽  
A. H. Nugent
Keyword(s):  
Cross Section ◽  
Fiber Optic ◽  
Reverse Flow ◽  
Laser Doppler Anemometer ◽  
Laser Doppler ◽  
Axial Component ◽  
Collapsible Tube ◽  
Two Component ◽  
Flow Through ◽  
The Cross

The flow field less than one diameter downstream of the end of a collapsible tube executing self-excited oscillations was examined using a two-component fiber-optic laser-Doppler anemometer. The time-averaged Reynolds number of the flow was 11,000. With the tube oscillating periodically, results obtained during many cycles of oscillation were combined to yield surface plots of the axial component over the cross section at 16 phases of the cycle. By combining measurements obtained with the laser probe in two different orientations, secondary flow vectors over the cross section were likewise constructed for 16 phases. The measurements showed strongly phasic turbulence intensity, with the phase of high intensity coinciding with the time of maximal tube collapse. Reverse flow occurred during much of the cycle, at places in the cross section that agree with our previous observations of laminar and turbulent steady flow through a rigid simulated collapsed tube.

scholarly journals Quasielastic Lepton Scattering off Two-Component Dark Matter in Hypercolor Model

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 708 ◽  
Author(s):  
Vitaly Beylin ◽  
Maxim Bezuglov ◽  
Vladimir Kuksa ◽  
Egor Tretiakov
Keyword(s):  
Dark Matter ◽  
Total Cross Section ◽  
Cross Section ◽  
Strong Dependence ◽  
Cosmic Ray ◽  
High Energy ◽  
Dominant Contribution ◽  
Quasielastic Scattering ◽  
Two Component ◽  
The Cross

The interaction of high-energy leptons with components of Dark Matter in a hypercolor model is considered. The possibility of detection, using IceCube secondary neutrinos produced by quasielastic scattering of cosmic ray electrons off hidden mass particles, is investigated. The dominant contribution to the cross section results from diagrams with scalar exchanges. A strong dependence of the total cross section on the Dark Matter components mass is also found.

Cross sections for the scattering of massless particles by graviton exchange

1970 ◽  
Vol 48 (8) ◽  
pp. 923-929 ◽  
Author(s):  
F. G. Peet
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Massless Particles ◽  
Scalar Particles ◽  
Two Component ◽  
Gravitational Scattering ◽  
The Cross

The gravitational scattering of various types of massless particles is considered. Cross sections are given for the gravitational scattering of scalar particles by: scalar particles, photons, four component neutrinos, and two component neutrinos; of photons by: photons, four component neutrinos, and two component neutrinos; of four component neutrinos by four component neutrinos; and of two component neutrinos by two component neutrinos. The cross section given by Barker et al. and by Boccaletti et al. for the scattering of photons by photons is confirmed. The cross section for the scattering of scalar particles by scalar particles given by DeWitt and the cross section for the scattering of photons by scalar particles given by Boccaletti et al. are found to be in error.

Shape Optimization of Power Plant Ducting Using CFD

2008 ◽  
Author(s):  
Ramesh Avvari ◽  
Sreenivas Jayanti ◽  
S. Gowrisankar
Keyword(s):  
Power Plant ◽  
Pressure Drop ◽  
Cross Section ◽  
High Velocity ◽  
Flow Simulation ◽  
Higher Power ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
The Cross ◽  
Flow Maldistribution

Power plant ducting generally designed with simple shapes has to undergo many changes of shape to accommodate interfacing equipment associated with plant operation leading to higher pressure drop, higher power consumption and flow maldistribution zones having higher or lower velocities. To redress this situation, baffles, guide vanes and other internals are used to streamline the flow through ducts, especially in bends. A basic disadvantage in coal fired plants of using baffles is that they get punctured / eroded due to impact of high velocity ash particles in flue gas ducting, and the effectiveness of baffles is lost in short duration. To overcome the above disadvantages, a new method is developed to change the shape of the duct in such a way that a more streamlined flow is maintained across any cross section. The velocity profile, obtained using computational fluid dynamics (CFD) calculations, across the cross-section is examined at several locations along the duct. Wherever high velocity compared to average velocity is found, the cross-section is increased and where the velocity is low, the cross-section is reduced. A new grid is created through the revised cross-section and a fresh CFD analysis is made to identify zones of flow maldistribution. The flow simulation is done in an iterative manner, alternately calculating the flow domain and modifying the local cross-section based on the local velocity distribution. The method has been found to be more robust and led, after a few iterations, to a shape of the duct which resulted in a significant reduction in the pressure drop without using any baffles or inserts.

The Deployment of Curved Closed Tubes

1996 ◽  
Vol 118 (3) ◽  
pp. 337-339 ◽  
Author(s):  
G. Greschik ◽  
K. C. Park
Keyword(s):  
Cross Section ◽  
Critical Review ◽  
The Other ◽  
Collapsible Tube ◽  
The Cross

A critical review of previous work on the unfurling of helically curved tubes (Greschik et al, 1994, 1996) is conducted, which leads to the proposition of a continuous and smooth deployment concept akin to the Collapsible Tube Mast (Aguirre, 1985) for curved tubes. This involves the collapse of the cross section and the subsequent roll-up of its halves one upon the other onto a storage drum. The concept’s applicability to closed tubes is investigated and a method for the alleviation of the deleterious membrane strains in the stowed state is proposed.

scholarly journals A Regression Line for a Laser Doppler Anemometer

2021 ◽  
Vol 9 (1) ◽  
pp. 12
Author(s):  
Karolina Weremijewicz ◽  
Andrzej Gajewski
Keyword(s):  
Air Conditioning ◽  
Solid Phase ◽  
Regression Line ◽  
Laser Doppler Anemometer ◽  
Vapor Condensation ◽  
Laser Doppler ◽  
Phase Flow ◽  
Two Phase ◽  
Two Fluids ◽  
Flow Through

Refrigeration and air conditioning consume 15% of the total generated electricity. Vapor condensation devices need a heat sink which may come in the form of absorption cycles devices. Two fluids, which change phase and concentration, flow through these devices. These changes take place amid a two-phase flow in contact with a solid phase. Hence, an extended study of the velocity profiles across the thin liquid layer is necessary, which is assumed to be conducted by a laser Doppler anemometer. The preliminary studies concerning the calibration of this anemometer are reported.

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