scholarly journals AiStudy on the Behavior of an Underwater Explosion Bubble near a Rigid Wall

2021 ◽  
Vol 9 ◽  
Author(s):  
Ching-Yu Hsu ◽  
◽  
Cho-Chung Liang ◽  
Vo-Phuong Duy ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Free Field ◽  
Underwater Explosion ◽  
Flow Simulation ◽  
Rigid Wall ◽  
Complex Structures ◽  
High Expectations ◽  
Jet Impact ◽  
Bubble Interaction ◽  
Explosive Charges

The dynamic approach to an underwater explosion (UNDEX) is a complex episode that involves shockwave propagation, bubble pulse with high pressure, and water jet impact. This paper proposes linkage of Finite Element Avenue (FEM) and Companion of Eulerian-Lagrangian (CEL) to supply promised data of large deformations and flow simulation of fluid and gas where the bubble interaction is near a stiff wall. To conduct the process, a 7.5 m x 9.0 m Eulerian domain and explosive charges of 10 g, 35 g, and 55 g TNT are built in a free field, respectively. Numerical analysis, as far as a comparison with research from E. Klaseboer, has been given in this study. The important results obtained from the CEL approach imply high expectations. In spite of the fact that this approach is not adequately consistent to totally supplant a live test, it can be utilized as an outline database to anticipate outcomes of managing an UNDEX with a high pressure bubble. The behavioral explosion from an UNDEX bubble near a rigid wall is a prospective contribution in this research. With these results, this technique can be used in further studies to examine UNDEX bubbles in the vicinity of deformable and complex structures.

The Application of CEL Technique to Simulate the Behavior of an Underwater Explosion Bubble in the Vicinity of a Rigid Wall

2020 ◽  
Vol 902 ◽  
pp. 126-139
Author(s):  
Anh Tu Nguyen
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Bubble Dynamics ◽  
Underwater Explosion ◽  
Flow Simulation ◽  
Rigid Wall ◽  
Water Jet ◽  
Complex Structures ◽  
Explicit Finite Element ◽  
Jet Impact

The dynamic process of an underwater explosion (UNDEX) is a complex phenomenon that involves several facets. After detonation, the shockwave radially propagates at a high speed and strikes nearby structures. Subsequently, bubble oscillation may substantially damage the structures because of the whipping effect, water jet impact, and bubble pulse. This paper presents an application of explicit finite element analyses to simulate the process of an UNDEX bubble in the vicinity of rigid wall, in which the coupled Eulerian-Lagrangian (CEL) approach was developed to overcome the difficulties regarding the classical finite element method (FEM), large deformations, and flow simulation of fluid and gas. The results demonstrate that the method is well suited to manage the UNDEX bubble problem and can be used to model the major features of the bubble dynamics. Furthermore, the behavior of an UNDEX bubble near a rigid wall was also examined in the present study, which showed that the migration of the bubble and the development of the water jet are influenced strongly by the standoff distance between the initial bubble position and the wall. This method can be used in future studies to examine UNDEX bubbles in the vicinity of deformable and complex structures.

scholarly journals A Numerical and Experimental Study of Wall Pressure Caused by an Underwater Explosion Bubble

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yingyu Chen ◽  
Xiongliang Yao ◽  
Xiongwei Cui
Keyword(s):  
High Speed ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Underwater Explosion ◽  
Rigid Wall ◽  
Numerical Results ◽  
Wall Pressure ◽  
Bubble Collapse ◽  
Strong Impact ◽  
Jet Impact

The bubble dynamics behaviors and the pressure in the wall center are investigated through experimental method and numerical study. In the experiment, the dynamics of an underwater explosion (UNDEX) bubble beneath a rigid wall are captured by high-speed camera and the wall pressure in the wall center is measured by pressure transducer. To reveal the process and mechanism of the pressure on a rigid wall during the first bubble collapse, numerical studies based on boundary element method (BIM) are applied. Numerical results with two different stand-off parameters (γ=0.38 and γ=0.90) show excellent agreement with experiment measurements and observations. According to the experimental and the numerical results, we can conclude that the first peak is caused by the reentrant jet impact and the following splashing effect enlarged the duration of the first jet impact. When γ=0.38, the splashing jet has a strong impact on the minimum volume bubble, a number of tiny bubbles, formed like bubble ring, are created and collapse more rapidly owing to the surrounding high pressure and emit multi shock waves. When γ=0.90, the pressure field around the bubble is low enough only a weak rebounding bubble peak occurs.

Air Bubble Entrainment, Breakup, and Interplay in Vertical Plunging Jets

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Numa Bertola ◽  
Hang Wang ◽  
Hubert Chanson
Keyword(s):  
High Speed ◽  
Point Explosion ◽  
Air Bubble ◽  
Bubble Breakup ◽  
Jet Impact ◽  
Bubble Entrainment ◽  
Bubble Interaction ◽  
Onset Velocity ◽  
Air Cavities ◽  
Interaction Behaviors

The entrainment, breakup, and interplay of air bubbles were observed in a vertical, two-dimensional supported jet at low impact velocities. Ultra-high-speed movies were analyzed both qualitatively and quantitatively. The onset velocity of bubble entrainment was between 0.9 and 1.1 m/s. Most bubbles were entrained as detached bubbles from elongated air cavities at the impingement point. Explosion, stretching, and dejection mechanisms were observed for individual bubble breakup, and the bubble interaction behaviors encompassed bubble rebound, “kiss-and-go,” coalescence and breakup induced by approaching bubble(s). The effects of jet impact velocity on the bubble behaviors were investigated for impact velocities from 1.0 to 1.36 m/s, in the presence of a shear flow environment.

scholarly journals SPH-BEM simulation of underwater explosion and bubble dynamics near rigid wall

2019 ◽  
Vol 62 (7) ◽  
pp. 1082-1093 ◽  
Author(s):  
ZhiFan Zhang ◽  
Cheng Wang ◽  
A-Man Zhang ◽  
Vadim V Silberschmidt ◽  
LongKan Wang
Keyword(s):  
Bubble Dynamics ◽  
Underwater Explosion ◽  
Rigid Wall

On High Pressure Squeeze Pack Numerical Simulation of Unconsolidated Sandstone Based on Discrete Element

2010 ◽  
Vol 34-35 ◽  
pp. 1666-1670
Author(s):  
Wei Zhang Wang ◽  
Xiang Zhen Yan
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Flow Simulation ◽  
Discrete Element ◽  
Simulation Software ◽  
Oil Reservoir ◽  
Control Technology ◽  
Sand Control ◽  
Grain Flow ◽  
Element Theory

Sand inflow is one of the problems in unconsolidated sandstone oil reservoir recovery. The most frequently applied sandcontrol method is high-pressure gravel squeeze packing sand control technology. But incorrect knowledge of stratum shapes under high-pressure squeeze packing leads to unreasonable technology and implement parameters. This thesis, based on the discrete element theory and by means of two-dimension grain flow simulation software PFC2D, considers three oil wells with unconsolidated sandstone in terms of their cementing strengths . The simulation result shows that strata with diverse cementing strengths vary remarkably when high-pressure squeeze pack is asserted. Established calculation pattern might lead to sizable deviation.

Air Flow Simulation in High-Pressure Fan with Splitter Blade

2013 ◽  
Vol 805-806 ◽  
pp. 1730-1735
Author(s):  
Xiao Lin Wang ◽  
Ding Hua Yang ◽  
Gen Sheng Yang ◽  
Zhong Li ◽  
Jian Feng Li ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Total Pressure ◽  
Unstructured Grids ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Turbulent Model ◽  
Centrifugal Blower ◽  
The Mean

In the process of fans design, splitter blades could be adopted in the middle of rotator to improve the performance of fan. In order to understand the flow pattern in the high-pressure centrifugal blower of 9-26type with splitter blade thoroughly, computational fluid dynamics Fluent is applied and the three dimensional air flows in the fan is numerically simulated and analyzed. The calculating results showed that under the same condition, the flux of the fan was improved 5%approximately and the mean total pressure at outlet of the fan was improved 10% because of the splitter blade, the length of the splitter blade affected the flux either. Standard turbulent model and unstructured grids are applied in computation. The results of calculation can good helpful for people to improve the performance of the fan.

On the Dynamic Collapse of Cylindrical Shells Under Impulsive Pressure Loadings

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Luciana Loureiro da Silva Monteiro ◽  
Theodoro Antoun Netto ◽  
Paulo Cesar da Camara Monteiro
Keyword(s):  
Cylindrical Shells ◽  
Underwater Explosion ◽  
Acoustic Medium ◽  
Isotropic Hardening ◽  
Water Tank ◽  
Numerical Work ◽  
Collapse Pressure ◽  
Explosion Pressure ◽  
Explosive Charges ◽  
Impulsive Pressure

The dynamic collapse of submerged cylindrical shells subjected to lateral impulsive pressure loads caused by underwater explosions is studied via coupled experimental and numerical work. Two sets of experiments were performed. Initially, 50.8 mm outside diameter aluminum tubes with diameter-to-thickness ratio of 32.3 were tested inside a pressure vessel. Hydrostatic pressure was applied quasi-statically up to the onset of collapse in order to obtain the collapse pressure of the tubes tested. Subsequently, similar tubes were tested in a 5 m × 5 m × 1.6 m deep water tank under various explosive charges placed at different distances. Explosive charges and standoff distances were combined so as to eventually cause collapse of the specimens. Dynamic pressures were recorded using a fit-for-purpose data acquisition system with sampling rates of up to 1 mega samples/s/channel. In parallel, finite element models were developed using commercially available software to simulate underwater explosion, pressure wave propagation, its interaction with a cylindrical shell, and the subsequent onset of dynamic collapse. The surrounding fluid was modeled as an acoustic medium, the shells as J2 flow theory based materials with isotropic hardening, and proper fluid–structure interaction elements accounting for relatively small displacements of the boundary between fluid and structure were used. Subsequently, the physical explosion experiments were numerically reproduced with good correlation between results. Finally, a parametric study was carried out to examine the effect on the pipe under different impulsive pressure loads.

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