Model load in case of an internal explosion

2021 ◽  
Vol 30 (3) ◽  
pp. 5-15
Author(s):  
V. A. Gorev
Keyword(s):  
Numerical Modeling ◽  
Pressure Drop ◽  
Pressure Rise ◽  
Destructive Effect ◽  
Burst Effect ◽  
Pressure Drops ◽  
Internal Explosion ◽  
Beam Motion ◽  
Two Peaks ◽  
Second Peak

Introduction. Presently, there are no model loads that describe the burst effect of an internal explosion. The goal of the article is to design a model load that characterizes an internal explosion with regard for the effect of inertial safety structures. The author provides relevant examples.Methods. The experiment and the numerical modeling identify the characteristics of an internal explosion, primarily, its destructive effect. First of all, these characteristics include the pressure value and rate in the process of the first peak formation. A drop follows the first peak. Another rise to the second peak is followed by the final pressure drop. The rise to the first peak is described by a cubic parabola. The constant value of pressure is equal to the highest value of the two peaks. It replaces the drop and rise between the peaks. The linear dependence describes the area of the final pressure drop, so that the deformation is completed at the end point. The time of the pressure rise is determined by breakup, and it takes account of the characteristics of safety structures. The time of the second peak is the time when the flame area is maximal.Results and discussion. The deformation that may occur before the first peak represents a solution to the equation, describing the beam motion. This equation is provided in the article. The deformation between the peaks is determined by the balance of energy. The deformation, that occurs when the pressure drops, is identified by the solution to the motion equation. The solution is subject to the deformation completion condition.Conclusions. The results show that the time between the peaks is important when the pressure is close to maximal. The analysis identifies the conditions under which deformation remains elastic. These results can be contributed to the assessment of the bearing capacity of buildings that accommodate explosive production facilities. This approach ensures conservative results.

scholarly journals Assessment of structural bearing capacity in case of internal explosion

2021 ◽  
Vol 263 ◽  
pp. 02048
Author(s):  
Vyacheslav Gorev ◽  
Evgeniya Chelekova
Keyword(s):  
Load Capacity ◽  
Pressure Rise ◽  
Maximum Deformation ◽  
Maximum Value ◽  
Internal Explosion ◽  
Pressure Maximum ◽  
Protective Structures ◽  
Two Peaks ◽  
Rod Structures ◽  
Short Section

The work has developed a method for determining the deformation of bent rod structures during an internal explosion. When consideration of a quasi-stationary explosion, a model load is proposed, taking into account the pressure rise section to the maximum value at the beginning of the explosion, then a stationary section and then a decline. The pressure in the stationary area is equal to more of the two peaks. With a sufficiently long stationary section, the maximum deformation is realized here, and is also determined from the energy balance. In the case of a short section of stationary pressure, maximum deformation develops towards the end of the explosion after a pressure drop. The solutions are suitable for describing deformation of beams with different fastening at the ends and are limited to the case when the maximum value of the load does not exceed the resistance of the structure. The results of the work can be used in assessing the load capacity of elements of explosive industries, residential premises, taking into account the action of protective structures.

scholarly journals The study of multipeaked type-I X-ray bursts in the neutron star low-mass X-ray binary 4U 1636 − 536 with RXTE

2020 ◽  
Vol 501 (1) ◽  
pp. 168-178
Author(s):  
Chen Li ◽  
Guobao Zhang ◽  
Mariano Méndez ◽  
Jiancheng Wang ◽  
Ming Lyu
Keyword(s):  
Neutron Star ◽  
Flux Ratio ◽  
Light Curves ◽  
Type I ◽  
X Ray ◽  
Soft State ◽  
Peak Flux ◽  
Low Mass ◽  
Two Peaks ◽  
Second Peak

ABSTRACT We have found and analysed 16 multipeaked type-I bursts from the neutron-star low-mass X-ray binary 4U 1636 − 53 with the Rossi X-ray Timing Explorer (RXTE). One of the bursts is a rare quadruple-peaked burst that was not previously reported. All 16 bursts show a multipeaked structure not only in the X-ray light curves but also in the bolometric light curves. Most of the multipeaked bursts appear in observations during the transition from the hard to the soft state in the colour–colour diagram. We find an anticorrelation between the second peak flux and the separation time between two peaks. We also find that in the double-peaked bursts the peak-flux ratio and the temperature of the thermal component in the pre-burst spectra are correlated. This indicates that the double-peaked structure in the light curve of the bursts may be affected by enhanced accretion rate in the disc, or increased temperature of the neutron star.

scholarly journals Advanced Complex Analysis of the Thermal Softening of Nitrided Layers in Tools during Hot Die Forging

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 355
Author(s):  
Jakub Krawczyk ◽  
Paweł Widomski ◽  
Marcin Kaszuba
Keyword(s):  
Numerical Modeling ◽  
Surface Layer ◽  
Laboratory Tests ◽  
Complex Analysis ◽  
Nitrided Layer ◽  
Hot Forging ◽  
Thermal Softening ◽  
Effect Of Temperature ◽  
Destructive Effect ◽  
Forging Process

This article is devoted to the issues of thermal softening of materials in the surface layer of forging tools. The research covers numerical modeling of the forging process, laboratory tests of tempering of nitrided layers, and the analysis of tempering of the surface layer of tools in the actual forging process. Numerical modeling was supported by measuring the temperature inside the tools with a thermocouple inserted into the tool to measure the temperature as close to the surface as possible. The modeling results confirmed the possibility of tempering the die material. The results of laboratory tests made it possible to determine the influence of temperature on tempering at different surface layer depths. Numerical analysis and measurement of surface layer microhardness of tools revealed the destructive effect of temperature during forging on the tempering of the nitrided layer and on the material layers located deeper below the nitrided layer. The results have shown that in the hot forging processes carried out in accordance with the adopted technology, the surface layer of working tools is overheated locally to a temperature above 600 °C and tempering occurs. Moreover, overheating effects are visible, because the surface layer is tempered to a depth of 0.3 mm. Finally, such tempering processes lead to a decrease in the die hardness, which causes accelerated wear because of the abrasion and plastic deformation. The nitriding does not protect against the tempering phenomenon, but only delays the material softening process, because tempering occurs in the nitrided layer and in the layers deeper under the nitrided layer. Below the nitrided layer, tempering occurs relatively quickly and a soft layer is formed with a hardness below 400 HV.

Experimental and Computational Analyses of Pressure Differentials in Flexible Ducts With Different Bent Angles

2007 ◽  
Author(s):  
Ray R. Taghavi ◽  
Wonjin Jin ◽  
Mario A. Medina
Keyword(s):  
Pressure Drop ◽  
Static Pressure ◽  
Complex Geometry ◽  
Analysis Data ◽  
Secondary Flows ◽  
Low Flow ◽  
Pressure Drops ◽  
Pressure Distributions ◽  
Geometrical Effects ◽  
Cfd Analyses

A set of experimental analyses was conducted to determine static pressure drops inside non-metallic flexible, spiral wire helix core ducts, with different bent angles. In addition, Computational Fluid Dynamics (CFD) solutions were performed and verified by comparing them to the experimental data. The CFD computations were carried out to produce more systematic pressure drop information through these complex-geometry ducts. The experimental setup was constructed according to ASHRAE Standard 120-1999. Five different bent angles (0, 30, 45, 60, and 90 degrees) were tested at relatively low flow rates (11 to 89 CFM). Also, two different bent radii and duct lengths were tested to study flexible duct geometrical effects on static pressure drops. FLUENT 6.2, using RANS based two equations - RNG k-ε model, was used for the CFD analyses. The experimental and CFD results showed that larger bent angles produced larger static pressure drops in the flexible ducts. CFD analysis data were found to be in relatively good agreement with the experimental results for all bent angle cases. However, the deviations became slightly larger at higher velocity regimes and at the longer test sections. Overall, static pressure drop for longer length cases were approximately 0.01in.H2O higher when compared to shorter cases because of the increase in resistance to the flow. Also, the CFD simulations captured more pronounced static pressure drops that were produced along the sharper turns. The stronger secondary flows, which resulted from higher and lower static pressure distributions in the outer and inner surfaces, respectively, contributed to these higher pressure drops.

Experimental Study of Evaporation Heat Transfer Characteristics and Pressure Drops of R410A and R134a in a Multiport Mini-Channel

2009 ◽  
Author(s):  
Jatuporn Kaew-On ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
Evaporation Heat ◽  
Evaporation Heat Transfer ◽  
R 134A

The evaporation heat transfer coefficients and pressure drops of R-410A and R-134a flowing through a horizontal-aluminium rectangular multiport mini-channel having a hydraulic diameter of 3.48 mm are experimentally investigated. The test runs are done at refrigerant mass fluxes ranging between 200 and 400 kg/m2s. The heat fluxes are between 5 and 14.25 kW/m2, and refrigerant saturation temperatures are between 10 and 30 °C. The effects of the refrigerant vapour quality, mass flux, saturation temperature and imposed heat flux on the measured heat transfer coefficient and pressure drop are investigated. The experimental data show that in the same conditions, the heat transfer coefficients of R-410A are about 20–50% higher than those of R-134a, whereas the pressure drops of R-410A are around 50–100% lower than those of R-134a. The new correlations for the evaporation heat transfer coefficient and pressure drop of R-410A and R-134a in a multiport mini-channel are proposed for practical applications.

Swirling Annular Flow in a Steam Separator

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Hironobu Kataoka ◽  
Yusuke Shinkai ◽  
Shigeo Hosokawa ◽  
Akio Tomiyama
Keyword(s):  
Pressure Drop ◽  
Annular Flow ◽  
Nuclear Reactor ◽  
Water Pressure ◽  
Interfacial Friction ◽  
Pressure Drops ◽  
Pressure Transducers ◽  
Ring Configuration ◽  
Film Flows ◽  
Steam Separator

Effects of pick-off ring configuration on the separator performance of a downscaled model of a steam separator for a boiling water nuclear reactor are examined using various types of pick-off rings. The experiments are conducted using air and water. Pressure drops in a barrel and a diffuser and diameters and velocities of droplets at the exit of the barrel are measured using differential pressure transducers and particle Doppler anemometry, respectively. The separator performance does not depend on the shape of the pick-off ring but strongly depends on the width of the gap between the pick-off ring and the barrel wall. The pressure drop in the barrel is well evaluated using the interfacial friction factor for unstable film flows. Carry-under can be estimated using a droplet velocity distribution at the exit of the separator.

Shellside Waterflow Pressure Drop Distribution Measurements in an Industrial-Sized Test Heat Exchanger

1988 ◽  
Vol 110 (1) ◽  
pp. 60-67 ◽  
Author(s):  
H. Halle ◽  
J. M. Chenoweth ◽  
M. W. Wambsganss
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Operating Cost ◽  
Power Requirement ◽  
Pressure Drops ◽  
Pressure Losses ◽  
Finned Tubes ◽  
Heat Exchanger Design ◽  
Isothermal Water

Throughout the life of a heat exchanger, a significant part of the operating cost arises from pumping the heat transfer fluids through and past the tubes. The pumping power requirement is continuous and depends directly upon the magnitude of the pressure losses. Thus, in order to select an optimum heat exchanger design, it is is as important to be able to predict pressure drop accurately as it is to predict heat transfer. This paper presents experimental measurements of the shellside pressure drop for 24 different segmentally baffled bundle configurations in a 0.6-m (24-in.) diameter by 3.7-m (12-ft) long shell with single inlet and outlet nozzles. Both plain and finned tubes, nominally 19-mm (0.75-in.) outside diameter, were arranged on equilateral triangular, square, rotated triangular, and rotated square tube layouts with a tube pitch-to-diameter ratio of 1.25. Isothermal water tests for a range of Reynolds numbers from 7000 to 100,000 were run to measure overall as well as incremental pressure drops across sections of the exchanger. The experimental results are given and correlated with a pressure drop versus flowrate relationship.

scholarly journals Grid convergence study of a cyclone separator using different mesh structures

2017 ◽  
Vol 23 (3) ◽  
pp. 311-320 ◽  
Author(s):  
R.A.F. Oliveira ◽  
G.H. Justi ◽  
G.C. Lopes
Keyword(s):  
Pressure Drop ◽  
Collection Efficiency ◽  
Fluid Dynamic ◽  
Two Phase ◽  
Mesh Structure ◽  
Pressure Drops ◽  
Regular Elements ◽  
Grid Convergence ◽  
Grid Convergence Index ◽  
Mesh Structures

In a cyclone design, pressure drop and collection efficiency are two important performance parameters to estimate its implementation viability. The optimum design provides higher efficiencies and lower pressure drops. In this paper, a grid independence study was performed to determine the most appropriate mesh to simulate the two-phase flow in a Stairmand cyclone. Computational fluid dynamic (CFD) tools were used to simulate the flow in an Eulerian-Lagrangian approach. Two different mesh structure, one with wall-refinement and the other with regular elements, and several mesh sizes were tested. The grid convergence index (GCI) method was applied to evaluate the result independence. The CFD model results were compared with empirical correlations from bibliography, showing good agreement. The wall-refined mesh with 287 thousand elements obtained errors of 9.8% for collection efficiency and 14.2% for pressure drop, while the same mesh, with regular elements, obtained errors of 8.7% for collection efficiency and 0.01% for pressure drop.

scholarly journals Reflectance Spectrum of a Color Blue Generated by Curved Multilayer and Iridescent of the Elytron of the Calidea Signata Bug

2016 ◽  
Vol 12 (36) ◽  
pp. 1
Author(s):  
Issaka Ouedraogo ◽  
Serge Wendsida Igo ◽  
Priscilla Simonis ◽  
Alioune Ouedraogo ◽  
Belkacem Zeghmati
Keyword(s):  
Multilayer Structure ◽  
Reflectance Spectrum ◽  
Main Peak ◽  
Blue Color ◽  
Transfer Matrices ◽  
Microscopy Characterization ◽  
Two Peaks ◽  
Second Peak ◽  
Scanning Electron Microscopy Characterization ◽  
Scanning Electron

This paper focuses on the study of the origins of blue iridescent reflections of the elytron of Calidea Signata, of the pentatomidae family which is commonly known as bug. Indeed, we use the spectrophotometry measurements, scanning electron microscopy characterization technique, and a ray tracing code program combined with the transfer matrices method, to explain the structure which is responsible for the color of the blue reflections and the iridescent effect. Thus, we noticed that the color of the bug as a result of two peaks. The first and main peak is located at 485.5 nm, corresponding to the blue color. The second peak, is less intense at 525 nm, corresponding to the green-blue color. The numerical reproduction of the reflectance spectrum gives 510.25 nm for the main peak, and 539.5 nm for the secondary peak. These results confirm that the multilayer structure is responsible for the blue color of the Calidea Signata bug. Lastly, the curve of the multilayer is responsible for the iridescence.

scholarly journals Pemodelan Penurunan Tekanan Brine di Dalam Pipa Injeksi pada Lapangan Panas Bumi Dieng

Jurnal MIPA ◽  
2017 ◽  
Vol 6 (2) ◽  
pp. 32
Author(s):  
Jeferson Polii
Keyword(s):  
Pressure Drop ◽  
Flow Line ◽  
Chemical Constituents ◽  
Temperature Drop ◽  
Fluid Pressure ◽  
Saturation Temperature ◽  
Geothermal Field ◽  
Chemical Pollution ◽  
Pressure Drops ◽  
Very High

Injeksi brine hasil dari fluida produksi panas bumi digunakan untuk mengisi volume pori batuan reservoir, mencegah penurunan tekanan batuan yang terlalu cepat, dan mencegah polusi panas dan polusi kimia pada lingkungan yang disebabkan oleh kandungan kimia tertentu pada brine. Pada pipa aliran brine terjadi penurunan tekanan fluida sepanjang aliran. Di lapangan panas bumi Dieng, konsentrasi silika sangat tinggi, sehingga penurunan temperatur saturasi memicu desposisi silika. Penurunan tekanan sepanjang pipa aliran brine dari pompa Vertikal Atas (VA) 7 ke pond di pad 29 di lapangan panas bumi Dieng akan menyebabkan penurunan temperatur saturasi, selain juga kehilangan panas secara alami. Perhitungan penurunan tekanan fluida brine berdasarkan perhitungan Harrison-Freeston dan metode dari Zhao, yang dikembangkan dengan algoritma menggunakan Macro Excel. Sehingga dengan memodelkan penurunan tekanan sepanjang pipa alir, dapat dikembangkan untuk perhitungan penurunan temperatur dan pengendapan silika di pipa aliran brine untuk injeksi panas bumi.Brine injection from geothermal production fluids is used to fill reservoir pore rock volumes, preventing rapid rock pressure drops, and preventing heat pollution and chemical pollution in the environment caused by certain chemical constituents in the brine. Decrease fluid pressure along the flow on the brine flow pipe. In the Dieng geothermal field, the silica concentration is very high, so the decrease in saturation temperature triggers the silica desposition. The pressure drop along the brine flow pipe from the Upper Vertical (VA) 7 pump to the pond in pad 29 in Dieng geothermal field will cause a decrease in saturation temperature, as well as natural heat loss. The calculation of the decrease in brine fluid pressure based on Harrison-Freeston calculations and methods of Zhao, developed with algorithms using Macro Excel. By modeling the pressure drop along the flow line, it can be developed for the calculation of temperature drop and deposition of silica in the brine flow pipe for geothermal injection

Sign in / Sign up

Export Citation Format

Share Document