scholarly journals Internal explosion. Pressure peaks

2021 ◽  
Vol 263 ◽  
pp. 02041
Author(s):  
Vyacheslav Gorev ◽  
Evgeniya Chelekova
Keyword(s):  
Numerical Modeling ◽  
Small Volume ◽  
Pressure Change ◽  
Explosion Pressure ◽  
Scale Modeling ◽  
Gas Explosions ◽  
Internal Explosion ◽  
Pressure Dynamics ◽  
The Moment ◽  
Protective Structures

Internal emergency gas explosions occur at threatening intervals and cause significant destruction. The level of destruction indicates the imperfection of protection methods. Documents regulating the use of safety structures for the protection of buildings during an internal explosion are limited by the assignment of the area of openings covered by safety structures, without taking into account the properties of these structures, attachment methods and the rate of pressure increase during an explosion. The purpose of the work is to take into account as much as possible the influence of the properties of the protective structures, their attachment and the nature of the explosion on the dynamics of the explosion pressure change. The second goal is to obtain a methodology for converting the results of experimental results obtained on small volumes to determine the parameters of an explosion in conditions of large volume. The goals are achieved by the theory of dimensions and similarity using numerical modeling. The work revealed dimensionless complexes describing pressure dynamics both during opening of openings and at the moment of maximum power of energy release during explosion. Possibility of experimental scale modeling of processes of opening of safety structures is shown. In particular, it is shown that during an explosion in premises of a small volume (residential), the pressure during opening is more often critical.

scholarly journals About dependence of parameters of internal explosion on the device of safety designs in apertures of the protecting walls of the production and residential buildings

2018 ◽  
Vol 251 ◽  
pp. 02015 ◽  
Author(s):  
Vyacheslav Gorev
Keyword(s):  
Burning Rate ◽  
Small Volume ◽  
Residential Buildings ◽  
Unit Weight ◽  
Gas Explosion ◽  
Building Collapse ◽  
The Real ◽  
Explosion Pressure ◽  
Internal Explosion ◽  
Pressure Unit

Protection of buildings against consequences of gas explosion indoors by means of the safety designs (SD) is widespread. In a number of the regulating documents requirements to these designs are imposed. It agrees, the regulating documents are allowed to carry out calculation of system of protection against internal explosion by means of the safety designs. The key sizes determining the area of apertures of the blocked safety designs are: speed of explosive combustion, most allowed explosion pressure, unit weight (per acre) the safety designs and pressure of opening of the safety designs. Under pressure openings it is meant pressure with which communications of the safety designs with walls of the building collapse and the safety designs starts moving. Depth of seal of the safety designs in an aperture remains out of sight and is supposed what influences the end result a little. In the real article an attempt to deal with this question is made. As a result of the conducted researches it was established that depth of seal of the safety designs in an aperture has to be considered when calculating system of protection of buildings against internal explosion by means of the safety designs. Especially it is important for rooms of small volume of V0≤120 of m3. For the analysis of explosion in the production buildings it is necessary to consider the volume of these rooms and a possibility of increase in burning rate because of existence of barriers indoors.

scholarly journals Numerical modeling of interaction of the aircraft engine with concrete protective structures

2018 ◽  
Vol 946 ◽  
pp. 012050 ◽  
Author(s):  
P A Radchenko ◽  
S P Batuev ◽  
A V Radchenko ◽  
V S Plevkov
Keyword(s):  
Numerical Modeling ◽  
Aircraft Engine ◽  
Protective Structures

scholarly journals Experimental Study of Gas Explosions in Hydrogen Sulfide-Natural Gas-Air Mixtures

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
André Vagner Gaathaug ◽  
Dag Bjerketvedt ◽  
Knut Vaagsaether ◽  
Sandra Hennie Nilsen
Keyword(s):  
Experimental Study ◽  
Hydrogen Sulfide ◽  
Natural Gas ◽  
Turbulent Combustion ◽  
Reference Data ◽  
Pressure Transducers ◽  
Explosion Pressure ◽  
Gas Explosions ◽  
The Rich ◽  
Combustion Of Hydrogen

An experimental study of turbulent combustion of hydrogen sulfide (H2S) and natural gas was performed to provide reference data for verification of CFD codes and direct comparison. Hydrogen sulfide is present in most crude oil sources, and the explosion behaviour of pure H2S and mixtures with natural gas is important to address. The explosion behaviour was studied in a four-meter-long square pipe. The first two meters of the pipe had obstacles while the rest was smooth. Pressure transducers were used to measure the combustion in the pipe. The pure H2S gave slightly lower explosion pressure than pure natural gas for lean-to-stoichiometric mixtures. The rich H2S gave higher pressure than natural gas. Mixtures of H2S and natural gas were also studied and pressure spikes were observed when 5% and 10% H2S were added to natural gas and also when 5% and 10% natural gas were added to H2S. The addition of 5% H2S to natural gas resulted in higher pressure than pure H2S and pure natural gas. The 5% mixture gave much faster combustion than pure natural gas under fuel rich conditions.

scholarly journals Preliminary study on the tea dust explosion: the effect of tea dust size

2019 ◽  
Vol 255 ◽  
pp. 02014 ◽  
Author(s):  
Semawi Nur Hikmah ◽  
Sulaiman Siti Zubaidah ◽  
Ahmad Mutamim Noor Sabrina ◽  
Abdul Mudalip Siti Kholijah ◽  
Che Man Rohaida ◽  
...  
Keyword(s):  
Particle Size ◽  
Pressure Change ◽  
Dust Explosion ◽  
Particle Sizes ◽  
Drying Process ◽  
Chain Reaction ◽  
Explosion Pressure ◽  
Initial Shock ◽  
Preliminary Study ◽  
A Chain

Food-based dust is considered as combustible dust as they composed of distinct particles, regardless of the size or chemical composition and when suspended in air or any other oxidizing medium over a range of concentrations will present a fire or deflagration hazard. The explosion effect from food-based dust can cause catastrophic consequences because the initial shock wave from the explosion lift up more dust and triggers a chain reaction through the plant. One of the parameters that can enhance the explosion is the particle size of the dust. In this study, the effect of four different particle sizes of tea dust on the dust explosion severity was tested in a confined 20 L explosion bomb. Tea dust tends to explode due to its molecular structure which contains a carbon-hydrogen bond that can release the significant amount of thermal energy. The experimental results showed that the values of Pmax and (dP/dt)max of tea dust were more severe for the particle size of 160 ?m for which are 1.97 bar and 4.97 bar/s before drying and 2.09 bar and 7.01 bar/s after drying process. The finer dust reacted more violently than coarser ones. As particle size decreases, the rate of explosion pressure change increases, as long as the size is capable of supporting combustion.

A rotary compression test for determining the critical value of the Cockcroft–Latham criterion for R260 steel

2019 ◽  
Vol 29 (6) ◽  
pp. 874-886 ◽  
Author(s):  
Tomasz Bulzak ◽  
Zbigniew Pater ◽  
Janusz Tomczak ◽  
Łukasz Wójcik
Keyword(s):  
Numerical Modeling ◽  
Compression Test ◽  
Experimental Tests ◽  
Critical Value ◽  
Cross Wedge Rolling ◽  
Damage Criterion ◽  
Second Stage ◽  
State Of Stress ◽  
The Moment ◽  
Two Stages

A method for determining the critical value of the Cockcroft–Latham damage criterion is presented using the example of R260 railway steel. The determinations were performed using a rotary compression test specially developed for that purpose. The main object of the proposed test was to provide the best possible representation of the state of stress generated by cross-wedge rolling. The rotary compression test was performed in two stages: in the first stage, experimental tests were conducted to establish the moment of cracking of the specimen, and in the second stage, numerical modeling was used to determine the critical value of the Cockcroft–Latham criterion for the experimentally established cracking moment. The critical value of the Cockcroft–Latham criterion was determined under hot forming conditions.

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 Improvement of the calculation methodology for covering constructions of the covered field fortifications to ensure the survivability of troops in a modern armed conflict

2021 ◽  
pp. 282-295
Author(s):  
Oleksandr Voloshchenko ◽  
Mykola Kushnirenko ◽  
Ihor Chernykh
Keyword(s):  
Armed Conflict ◽  
High Explosive ◽  
Closed Field ◽  
Explosive Action ◽  
Covering Material ◽  
Calculation Methodology ◽  
The Moment ◽  
Protective Structures ◽  
Improved Technique ◽  
And Control

The task of improvement of the calculation methodology for covering constructions of the covered field fortifications against shell-hole, penetration, ricochet and high-explosive action is solved to ensure the survivability of troops in a modern armed conflict. An analysis of the 2014-2018 anti-terrorist operation and the ongoing Joint Forces operation proves that artillery, mortar and aircraft high-destructive munitions are currently the main means of firing the enemy. Under such conditions, the survival of our troops directly depends on their effective shelter in covered field fortifications. An important element of the arrangement of such fortifications is the calculation of the structures of their covering against penetration, shell-holing, ricocheting and high-explosive action, which are performed to determine the structure of the covering, its material and thickness. The novelty of the improved technique, unlike the existing ones, is that the calculations of the covering structures take into account the shape of the warhead of artillery, mortar and aircraft ammunition, the angle of encounter and the final speed of these munitions at the moment of their impact on the covered fortification and the pliability of the covering material. Here are given the examples of calculation for the closed field fortifications structures against penetration of the warhead into the covering material, cases of punching the covering material enclosed with brittle material, ricochet of the warhead from the covering and destruction of the covering as a result of high explosive action. The obtained results will be used to calculate the protective structures of long-term fortifications for command and control centres and field hospitals.

Lapping Control of Hard Disk Drive Heads: Part II—Control

2000 ◽  
Author(s):  
Youping Mei ◽  
Kim A. Stelson
Keyword(s):  
Numerical Modeling ◽  
Hard Disk Drive ◽  
Process Model ◽  
Disk Drive ◽  
Parameter Uncertainties ◽  
System Experiment ◽  
Pressure Dynamics ◽  
Trajectory Following ◽  
Good Preparation

Abstract Using numerical modeling as a tool, the pressure dynamics of bar lapping is identified. The process model is constructed based on the pressure dynamics and the Preston model. A controller is then designed using a trajectory following formulation. Simulation of the controller designed as such shows that it is robust to parameter uncertainties. This controller is implemented on a Seagate lapping system. Experiment results show that the proposed method is less sensitive to the quality of the preparation processes. However, the gains should be appropriately adjusted for optimal performance. With good preparation processes and appropriate gains, performance of the two methods are statistically comparable. Otherwise, the proposed method performs better. The proposed method is inferior to the existing method only when its gains are improperly adjusted.

Une supercherie collaborative: Claude Bonnefoy et Denis Roche dans l'ombre de Marc Ronceraille

2019 ◽  
Vol 58 (3) ◽  
pp. 348-365
Author(s):  
David Martens
Keyword(s):  
Small Volume ◽  
The Other ◽  
Substantial Part ◽  
Literary Critic ◽  
The Public ◽  
The Moment

Published in 1978, Marc Roncaille by Claude Bonnefoy is a hapax in the « Écrivains de toujours » collection. It introduces an author invented from scratch by Bonnefoy, with the active complicity of the collection's director, Denis Roche, himself the author of a substantial part of the photographs that illustrate the book. This small volume appears as a carnivalesque gesture at the moment of crossing a symbolic threshold, that of the hundredth volume of the series. Suffice it to say that if this monograph relating to an imaginary writer did not really fool the public, it presents the singular characteristic of being the fruit of the work of two creators, each moving to a different field of production and therefore a different status: from a literary critic to that of writer (Bonnefoy), with the other (Roche) extending his range of activities from that of publisher to that of photographer.

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