scholarly journals Effect of Computational Parameters on Output Properties of Underwater Explosion by Intelligent Numerical Simulation

2021 ◽  
Vol 2083 (3) ◽  
pp. 032086
Author(s):  
Yonghui Zheng ◽  
Jifeng Wei ◽  
Rui Xiao
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Near Field ◽  
Great Influence ◽  
Underwater Explosion ◽  
Propagation Distance ◽  
Rigid Boundary ◽  
Simple Method ◽  
Mesh Density ◽  
Explosion Load

Abstract The computational parameters are of great influence on underwater explosion load. A one-dimensional wedge model is established to analyze the influence of boundary condition (BC), water domain and mesh density on the numerical simulation results. The results show that flowout BC is rigid boundary and transmit BC is not suitable for simulating the collapses phase of bubble pulsation. According to propagation distance of shock wave and its reflected wave, a simple method to calculate appropriate water domain is proposed. A positive correlation between mesh density (λ) and calculated peak pressure of shock wave (P m) is found. When λ tends to infinity, simulated Pm in near field is quite reliable, but the values in relatively far field are lower than empirical results.

scholarly journals A Lab-Scale Experiment Approach to the Measurement of Wall Pressure from Near-Field under Water Explosions by a Hopkinson Bar

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Xiongwei Cui ◽  
Xiongliang Yao ◽  
Yingyu Chen
Keyword(s):  
Shock Wave ◽  
Near Field ◽  
Underwater Explosion ◽  
Experimental System ◽  
Hopkinson Bar ◽  
Wall Pressure ◽  
Pressure Loading ◽  
Target Plate ◽  
Wave Pressure ◽  
Shock Wave Pressure

Direct measurement of the wall pressure loading subjected to the near-field underwater explosion is of great difficulty. In this article, an improved methodology and a lab-scale experimental system are proposed and manufactured to assess the wall pressure loading. In the methodology, a Hopkinson bar (HPB), used as the sensing element, is inserted through the hole drilled on the target plate and the bar’s end face lies flush with the loaded face of the target plate to detect and record the pressure loading. Furthermore, two improvements have been made on this methodology to measure the wall pressure loading from a near-field underwater explosion. The first one is some waterproof units added to make it suitable for the underwater environment. The second one is a hard rubber cylinder placed at the distal end, and a pair of ropes taped on the HPB is used to pull the HPB against the cylinder hard to ensure the HPB’s end face flushes with loaded face of the target plate during the bubble collapse. To validate the pressure measurement technique based on the HPB, an underwater explosion between two parallelly mounted circular target plates is used as the validating system. Based on the assumption that the shock wave pressure profiles at the two points on the two plates which are symmetrical to each other about the middle plane of symmetry are the same, it was found that the pressure obtained by the HPB was in excellent agreement with pressure transducer measurements, thus validating the proposed technique. To verify the capability of this improved methodology and experimental system, a series of minicharge underwater explosion experiments are conducted. From the recorded pressure-time profiles coupled with the underwater explosion evolution images captured by the HSV camera, the shock wave pressure loading and bubble-jet pressure loadings are captured in detail at 5  mm, 10  mm, …, 30  mm stand-off distances. Part of the pressure loading of the experiment at 35  mm stand-off distance is recorded, which is still of great help and significance for engineers. Especially, the peak pressure of the shock wave is captured.

Behavior of Bubble in Small Water Tank Used for Food Processing Using Underwater Shock Wave

2011 ◽  
Vol 673 ◽  
pp. 225-230 ◽  
Author(s):  
Hideki Hamashima ◽  
Manabu Shibuta ◽  
Shigeru Itoh
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Food Processing ◽  
High Speed ◽  
Underwater Explosion ◽  
Video Camera ◽  
Experimental Result ◽  
Water Tank ◽  
Underwater Shock Wave ◽  
Small Water

The food processing technology using a shock wave can prevent deterioration of the food by heat because it can process food in a short time. Generally, since the shock wave used for food processing is generated by underwater explosion, the load of a shock wave to the food becomes very complicated. Therefore, in order to process safely, it is important to clarify the behaviors of the shock wave and the bubble pulse generated by underwater explosion. In this research, in order to investigate the behavior of the shock wave in the water tank used for food processing, the optical observation experiment and the numerical simulation were performed. In the experiment, the shock wave generated by underwater explosion was observed with the high-speed video camera. The numerical simulation about the behavior of bubble pulse was performed using analysis software LS-DYNA. Comparing and examining were performed about the experimental result and the numerical simulation result. The result of the numerical simulation about the behavior of the shock wave generated by underwater explosion and the shock wave generated by the bubble pulse and the bubble pulse was well in agreement with the experimental result.

scholarly journals The Fluid-Solid Interaction Dynamics between Underwater Explosion Bubble and Corrugated Sandwich Plate

2016 ◽  
Vol 2016 ◽  
pp. 1-21
Author(s):  
Hao Wang ◽  
Yuan Sheng Cheng ◽  
Jun Liu ◽  
Lin Gan
Keyword(s):  
Shock Wave ◽  
Failure Modes ◽  
Sandwich Structures ◽  
Numerical Models ◽  
Near Field ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Bubble Collapse ◽  
Fe Model ◽  
Wave Load

Lightweight sandwich structures with highly porous 2D cores or 3D (three-dimensional) periodic cores can effectively withstand underwater explosion load. In most of the previous studies of sandwich structure antiblast dynamics, the underwater explosion (UNDEX) bubble phase was neglected. As the UNDEX bubble load is one of the severest damage sources that may lead to structure large plastic deformation and crevasses failure, the failure mechanisms of sandwich structures might not be accurate if only shock wave is considered. In this paper, detailed 3D finite element (FE) numerical models of UNDEX bubble-LCSP (lightweight corrugated sandwich plates) interaction are developed by using MSC.Dytran. Upon the validated FE model, the bubble shape, impact pressure, and fluid field velocities for different stand-off distances are studied. Based on numerical results, the failure modes of LCSP and the whole damage process are obtained. It is demonstrated that the UNDEX bubble collapse jet local load plays a more significant role than the UNDEX shock wave load especially in near-field underwater explosion.

scholarly journals Calibration of Numerical Simulation Methods for Underwater Explosion with Centrifugal Tests

2019 ◽  
Vol 2019 ◽  
pp. 1-19
Author(s):  
Qiusheng Wang ◽  
Shicong Liu ◽  
Haoran Lou
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Peak Pressure ◽  
Bubble Radius ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Mesh Size ◽  
State Equation ◽  
Pulsation Period ◽  
Bubble Pulsation

The centrifugal underwater explosion tests and corresponding numerical simulations were carried out to study the laws of shock wave and bubble pulsation. A semiempirical method to determine JWL state equation parameters was given. The influence on numerical results caused by factors such as state equation of water, boundary condition, and mesh size was analyzed by comparing with the centrifugal underwater explosion test results. The results show that the similarity criterion is also suitable in numerical simulation; the shock wave peak pressure calculated by polynomial state equation is smaller than that of shock state equation. However, the maximum bubble radius and the pulsation period calculated by the two equations are almost the same. The maximum bubble radius is mainly affected by the boundary simulating the test model box, and the pulsation period is mainly affected by the artificial cutoff boundary. With the increase of standoff distance of measuring point, the mesh size required for the numerical calculation decreases; the size of the two-dimensional model is recommended to take 1/30 ∼ 1/10 explosion radius. In three-dimensional models, when mesh size is 2 times larger than explosion radius, the bubble motion change in the second pulsation period is not obvious. When mesh size is smaller than 1 time explosive radius, the full period of bubble pulsation can be well simulated, but calculation errors increase slowly and computation time greatly increases, so the three-dimensional mesh size is suggested to take the charge radius. Shock wave peak pressure is basically unaffected by gravity. As the gravity increases, the bubble maximum radius and the first pulsation period both decrease.

Numerical Simulation on Embedded Steel Frame Concrete Blast Wall Resisting Air Shock Wave

2014 ◽  
Vol 548-549 ◽  
pp. 1763-1767
Author(s):  
Hai Jun Wang ◽  
Yong Yao ◽  
Zhao Qiang Zhang ◽  
Xiao Pan Yang ◽  
Yu Ping Zhu
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Blast Wave ◽  
Steel Frame ◽  
Wave Load ◽  
Air Blast ◽  
Explicit Finite Element ◽  
Finite Element Software ◽  
Explosion Load ◽  
Wave Problems

Embedded steel frame concrete blast walls can effectively counteract and dissipation the air-blast wave of the explosion. By contrast widely recognized air-blast wave empirical formula to verify the feasibility of the method of explosion load simplify model numerical simulation calculate the shock wave problems by using the explicit finite element software ANSYS/LS-DYNA and keywords *LOAD_BLAST. Obtained, The results of simplified explosion shock wave load by *load_blast have small difference with the actual explosion model; The destruction of the wall are mainly shear and brittle failure; The ability of Embedded steel frame blast wall resist air-blast wave significantly greater than other wall.

scholarly journals Analysis of the Characteristics and Influencing Factors of Gas Explosion in Heading Face

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xue-bo Zhang ◽  
Jian-liang Gao ◽  
Jing-zhang Ren ◽  
Chun-xia Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Influencing Factors ◽  
Geometric Model ◽  
Great Influence ◽  
Ignition Energy ◽  
Gas Explosion ◽  
Step Size ◽  
Time Step ◽  
Time Space

In order to accurately grasp the characteristics and influencing factors of gas explosion in heading face, the mathematical model of gas explosion was determined. According to the actual size of a heading face of a coal mine, a 3D geometric model with a length of 100 m was established, and the effects of ignition energy and gas explosion equivalent on the gas explosion characteristics of the heading face were analyzed. The results show the following. (1) The mathematical models for numerical simulation of gas explosion can accurately simulate the gas explosion and its propagation process. The time-space step size has a great influence on the simulation results. The grid spacing for numerical simulation of mine gas explosion is determined to be 0.1 m and the time step length is determined to be 0.001 s. (2) The ignition energy has a limited effect on gas explosion characteristics. It only has a certain influence on the gas explosion process, but has little influence on the overpressure of shock wave. The larger the ignition energy is, the faster the explosion reaction speed is, and the maximum overpressure increases slightly. When the ignition energy increases to a certain value, the time of peak shock wave and the maximum overpressure both tend to be stable. The ignition energy has little effect on gas explosion characteristics when an explosion accident occurs underground with a large amount of gas accumulation. (3) The gas explosion equivalent has a great influence on the overpressure of gas explosion shock wave. The higher the explosion equivalent is, the greater the pressure is, and the peak value of the shock wave overpressure increases with the explosion equivalent as a power function. The research results have important guiding significance for the research and development of new technology for prevention and control of gas explosion.

scholarly journals Damage Characteristics of Polymer Plates under the Impact of the Near-Field and Contact Underwater Explosion

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Shucan Liu ◽  
Xiaohua Zhao ◽  
Hongyuan Fang ◽  
Xueming Du ◽  
Binghan Xue
Keyword(s):  
Shock Wave ◽  
Near Field ◽  
Underwater Explosion ◽  
Damage Mode ◽  
Distribution Characteristics ◽  
Emulsion Explosive ◽  
Damage Characteristics ◽  
Contact Explosion ◽  
Spatial Distribution Characteristics ◽  
The Impact

In order to study the damage characteristics of polymer plates under the impact of the underwater explosion, the underwater contact and near-field explosion tests of polymer plates were conducted using different explosive quantities. In this paper, eight polymer plates with the size of 500 mm × 500 mm × 60 mm were made, and eight groups of explosion tests were carried out by using the rock emulsion explosive and nonconductive detonators. The damage modes and spatial distribution characteristics of the polymer plate generated by the underwater contact and near-field explosion impact with different explosive quantities are compared and analyzed. In addition, the characteristics of the shock wave propagation in the plates are investigated. It can be observed that the main damage mode of polymer plate is overall damage under the contact underwater explosion. For the near-field explosion, the main damage mode changes to overall failure, and the damage of contact explosion to polymer plate is greater than that of underwater near-field explosion. The polymer plate can reduce and delay the shock wave effectively, but the effect decreases with the increase of explosive quantity in the underwater contact explosion.

Study on Damage Capabilities of Multiple Hulls Structure under Underwater Explosion

2012 ◽  
Vol 430-432 ◽  
pp. 1581-1586
Author(s):  
Fang Yi Zhou ◽  
Tao Jiang ◽  
Wei Li Wang ◽  
Ke Yu Zhang ◽  
Fa Min Zhan
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Stress Distribution ◽  
Underwater Explosion ◽  
Damage Mechanism ◽  
Copper Plate ◽  
Aluminum Plate ◽  
Armor Plate ◽  
Rubber Plate

In order to study the damage capabilities of multiple hulls structure under underwater explosion, the damage mechanism of contact blasting and noncontact blasting on target is analyzed, and the formula of shock wave in water goes through multiple hulls structure is put forward. Using armor plate and aluminum plate、copper plate、rubber plate as models respectively, numerical simulation is done by LS-DYNA, the stress distribution and displacement of multiple hulls structure under underwater contact blasting are got. Lastly, test research on damage capabilities of multiple hulls structure under underwater explosion is finished. The result shows that the anti-explosion capabilities of multiple hulls will improve greatly when underwater ship adopted this kind of structure.

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