The flow of swirling water through a convergentdivergent nozzle

1957 ◽  
Vol 3 (3) ◽  
pp. 261-274 ◽  
Author(s):  
A. M. Binnie ◽  
G. A. Hookings ◽  
M. Y. M. Kamel
Keyword(s):  
Axial Flow ◽  
Low Pressure ◽  
Wall Pressure ◽  
Core Diameter ◽  
Convergent Nozzle ◽  
Marked Influence ◽  
The Core ◽  
Air Core ◽  
Pressure Tests

Experiments with Perspex nozzles, which were arranged to discharge vertically downwards and in which the convergent part was followed by a short divergency, showed that at low swirls the flow was unstable. When the swirl was sufficiently large for an air core to be established, its effective magnitude was estimated from measurements, at the throat, of the core diameter and of the wall pressure. The former were in closer accord with inviscid theory than the latter. The results are presented in terms of dimensionless discharge and swirl coefficients. Measurements of core diameter and wall pressure were also made throughout one of the nozzles and compared with the theory. Reversed axial flow in the upper part of the nozzles was easily produced, and the limits of its appearance were determined. Low pressure tests with the reservoir top alternately submerged and uncovered revealed that the top had a marked influence on the nature of the flow in the nozzle; and measurements of the tangential and axial velocities in the upper part of the nozzle proved the inviscid theory to be seriously in error at high swirls. For purposes of comparison, similar experiments were performed on a convergent nozzle.

The flow of swirling water down a vertical and an inclined tube

1968 ◽  
Vol 304 (1479) ◽  
pp. 387-406 ◽  
Keyword(s):  
Theoretical Analysis ◽  
Swirling Flow ◽  
Wall Pressure ◽  
Core Diameter ◽  
The Core ◽  
Air Core ◽  
Total Head ◽  
Inclined Tube ◽  
Flow Through

Water with a controllable amount of swirl was admitted to a long Perspex tube which could be held at any angle. At tappings along the tube, the wall pressure and the air core diameter were measured, colour bands were inserted at various radii, and total-head traverses across the stream were made. From these observations the distribution was determined of the axial and tangential components of velocity, which were about 10 to 15 ft. /s. Experiments were made when the outlet was partly blocked, causing a jump to form, and also when it was unobstructed as in a 'vortex drop'. For both states the inviscid theory of the motion is derived; but agreement with the experiments is not close because, as in swirling flow through a nozzle, the shearing action in the stream was intense. The core sometimes assumed a helical shape of its own accord, and always took this form after the stream had been forced round a bend. Observations of these effects are compared with theoretical analysis.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

scholarly journals Geometrical Scaling of Antiresonant Hollow-Core Fibers for Mid-Infrared Beam Delivery

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 420
Author(s):  
Ang Deng ◽  
Wonkeun Chang
Keyword(s):  
Structural Parameters ◽  
Transmission Band ◽  
Confinement Loss ◽  
Hollow Core ◽  
Core Size ◽  
Core Diameter ◽  
Mid Infrared ◽  
The Core ◽  
Tubular Type ◽  
Beam Delivery

We numerically investigate the effect of scaling two key structural parameters in antiresonant hollow-core fibers—dielectric wall thickness of the cladding elements and core size—in view of low-loss mid-infrared beam delivery. We demonstrate that there exists an additional resonance-like loss peak in the long-wavelength limit of the first transmission band in antiresonant hollow-core fibers. We also find that the confinement loss in tubular-type hollow-core fibers depends strongly on the core size, where the degree of the dependence varies with the cladding tube size. The loss scales with the core diameter to the power of approximately −5.4 for commonly used tubular-type hollow-core fiber designs.

Determination of all Dimensions of CdSe Seeded CdS Nanorods Solely via their UV/Vis Spectra

2017 ◽  
Vol 231 (1) ◽  
Author(s):  
Patrick Adel ◽  
Julian Bloh ◽  
Dominik Hinrichs ◽  
Torben Kodanek ◽  
Dirk Dorfs
Keyword(s):  
Absorption Spectra ◽  
Extinction Coefficient ◽  
Core Diameter ◽  
The Core ◽  
Extinction Spectra ◽  
Cds Nanorods ◽  
Fast Route ◽  
Characteristic Points ◽  
Electron Microscopical

AbstractIn the present manuscript we develop a method to determine all characteristic dimensions of CdSe seeded CdS nanorods solely via their extinction spectra without the need for electron microscopical investigations. In detail, the core diameter as well as the overall diameter and length and the molar extinction coefficient can all be derived from characteristic points in the absorption spectra. We carefully investigate in which size regime our assumptions are valid and give an estimation of the expected error, making it possible for the reader to decide whether this method is sufficiently accurate for their respective system. Our method displays a comfortable and fast route to analyze these nowadays often used nanorods.

scholarly journals Assessment of Severe Accident Management for Small IPWR under an ESBO Scenario

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Hao Yu ◽  
Minjun Peng
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Lower Pressure ◽  
Severe Accident ◽  
Maximum Temperature ◽  
Pressurized Water ◽  
The Core ◽  
Severe Accidents ◽  
Accident Management ◽  
Degradation Studies

Interest in evaluation of severe accidents induced by extended station blackout (ESBO) has significantly increased after Fukushima. In this paper, the severe accident process under the high and low pressure induced by an ESBO for a small integrated pressurized water reactor (IPWR)-IP200 is simulated with the SCDAP/RELAP5 code. For both types of selected scenarios, the IP200 thermal hydraulic behavior and core meltdown are analyzed without operator actions. Core degradation studies firstly focus on the changes in the core water level and temperature. Then, the inhibition of natural circulation in the reactor pressure vessel (RPV) on core temperature rise is studied. In addition, the phenomena of core oxidation and hydrogen generation and the reaction mechanism of zirconium with the water and steam during core degradation are analyzed. The temperature distribution and time point of the core melting process are obtained. And the IP200 severe accident management guideline (SAMG) entry condition is determined. Finally, it is compared with other core degradation studies of large distributed reactors to discuss the influence of the inherent design characteristics of IP200. Furthermore, through the comparison of four sets of scenarios, the effects of the passive safety system (PSS) on the mitigation of severe accidents are evaluated. Detailed results show that, for the quantitative conclusions, the low coolant storage of IP200 makes the core degradation very fast. The duration from core oxidation to corium relocation in the lower-pressure scenario is 53% faster than that of in the high-pressure scenario. The maximum temperature of liquid corium in the lower-pressure scenario is 134 K higher than that of the high-pressure scenario. Besides, the core forms a molten pool 2.8 h earlier in the lower-pressure scenario. The hydrogen generated in the high-pressure scenario is higher when compared to the low-pressure scenario due to the slower degradation of the core. After the reactor reaches the SAMG entry conditions, the PSS input can effectively alleviate the accident and prevent the core from being damaged and melted. There is more time to alleviate the accident. This study is aimed at providing a reference to improve the existing IPWR SAMGs.

scholarly journals Spanwise structure of wall pressure on a cylinder in axial flow

1999 ◽  
Vol 11 (1) ◽  
pp. 151-161 ◽  
Author(s):  
Arun L. W. Bokde ◽  
Richard M. Lueptow ◽  
Bruce Abraham
Keyword(s):  
Axial Flow ◽  
Wall Pressure

The Development of the Evolutionary BWR (AB1600)

2008 ◽  
Author(s):  
Akira Murase ◽  
Mikihide Nakamaru ◽  
Ryoichi Hamazaki ◽  
Masahiko Kuroki ◽  
Munetaka Takahashi
Keyword(s):  
Fuel Cycle ◽  
Safety System ◽  
Safety Performance ◽  
Passive Safety ◽  
Main Role ◽  
Core Diameter ◽  
The Core ◽  
Passive Safety System ◽  
Bundle Size ◽  
Near Term

Considering the delay of the first breeding reactor (FBR), it is expected that the light water reactor will still play the main role of the electric power generation in the 2030’s. Accordingly, Toshiba has been developing a new conceptual ABWR as the near-term BWR. We tentatively call it AB1600. The AB1600 has introduced the hybrid active/passive safety system in order to have independent countermeasure for severe accidents and better probability of core damage frequency (CDF) considered external events such as earthquake. On the other hand, we have another goal of the AB1600, which is to retain the safety performance superior or equivalent to the current ABWR without deterioration of economy. In order to achieve both economy and safety performance, we have optimized the safety system configuration of the AB1600 by partly introducing passive safety system to design basis event (DBEs). At the same time, we have adopted the simplification of the overall plant systems in order to improve economy. In order to reduce capital cost, to shorten refueling period and to reduce maintenance effort, the AB1600 introduces the large fuel bundle size. The bundle size is 1.2 times as large as that of the ABWR and the fuel rod array is 12 by 12. And then by progressing the core design, we can reduce the number of reactor internal pumps (RIPs) to eight from the current ABWR of ten. The core power density, the number of fuel bundles, and the core diameter of AB1600 are decided in order to achieve 24 months fuel cycle length on the condition with below 5wt% enrichment of fuel and with eight RIPs.

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