Numerical Simulation of Peak Overpressure and Positive Pressure Time of Explosion Shock Wave in the Air

2012 ◽  
Vol 472-475 ◽  
pp. 1500-1504 ◽  
Author(s):  
Chao Liu ◽  
Zhi Jian Hu ◽  
Yun Yang Wang ◽  
Tao Dai
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Empirical Formula ◽  
Positive Pressure ◽  
Pressure Time ◽  
Simulation Results

A new rational peak overpressure formula about scale distance has been summarized by comparing differences of domestic and foreign scholars’ empirical formula. AUTODYN has been used to simulate the shock wave in the air by taking different mesh sizes. Comparing the numerical simulation results and empirical formula results, only when the scale distance is too small, two results about peak overpressure have certain deviation. But both results about positive pressure time are similar.

Numerical Simulation of Shock Wave in Air Based on FCT Method

2013 ◽  
Vol 397-400 ◽  
pp. 270-273
Author(s):  
Ying Li ◽  
Xiao Bin Li ◽  
Yu Wang ◽  
Wei Zhang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Comparative Analysis ◽  
Numerical Method ◽  
Blast Wave ◽  
Empirical Formula ◽  
Godunov Method ◽  
Numerical Accuracy

Blast wave is numerical simulated based on FCT method. According to the comparative analysis, taking Henrych empirical formula as a standard, FCT method is more accuracy than Godunov method. Moreover, it has been found that the numerical accuracy is insufficient when the distance is small, it is necessary to develop and modify the numerical method continuously.

Research of Shock Wave Damage Evaluation Method Based on LY-12 Effect Plate

2014 ◽  
Vol 532 ◽  
pp. 88-95
Author(s):  
Li Ping Li ◽  
De Ren Kong ◽  
Chuan Rong Zhao ◽  
Yu Hang ◽  
Fan Yang ◽  
...  
Keyword(s):  
Shock Wave ◽  
Finite Element ◽  
Evaluation Method ◽  
Structural Characteristics ◽  
Specific Impulse ◽  
Aluminum Plate ◽  
Positive Pressure ◽  
Plate Deformation ◽  
Finite Element Software ◽  
Pressure Time

This paper discusses the problems in electrometric method of measuring shock wave pressure, including frequency characteristic and installation method of the sensor, parasitic effect in damage conditions, as well as the unduplication of measuring environment and so on. These problems will lead to serious distortion. In this paper, on the structural characteristics of damage target, shock wave equivalent target method is proposed. The article discusses the use of methods and principles of equivalent target, uses the finite element software to do modal analysis with 1.5mm thickness aluminum plate and analyses the effects of shock wave to simulation results with different rise time, positive pressure time and specific impulse. Through sequentially loading gradient in 0.005Mpa~10MPa range to LY-12 aluminum plate in size of, target plate deformation damage can be observed. By using finite element numerical simulation, shock wave power of different equivalent explosion field can be reflected qualitatively.

Research on Characteristics of Flow Field Inside Tangential Inlet Cyclone Separator

2012 ◽  
Author(s):  
Yigang Luan ◽  
Pengfei Liu ◽  
Haiou Sun ◽  
Yulin Deng
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Empirical Formula ◽  
Research Result ◽  
Internal Flow ◽  
Cyclone Separator ◽  
Resistance Characteristic ◽  
Simulation Results ◽  
Tangential Inlet ◽  
Simulation Scheme

Flow field inside tangential cyclone separator is a kind of complex three-dimensional rotation turbulent flow. To optimize the flow field structure and shorten the cycle of research and development, it is essential to find an appropriate calculation method to predict the flow field inside cyclone separators. In the article, FLUENT software is employed to obtain the internal flow field of tangential inlet cyclone separator by adopting different calculation models and different numerical simulation scheme. Also the simulation result was compared with that of existing experiment data to find a reasonable solution for the simulation of the flow field characteristics inside the cyclone. After the examination to the rationality of the different numerical simulation method, and the comparative analysis in the main flow field parameters of the simulated results which is the most reasonable combination, the flow characteristics of internal flow field of tangential inlet cyclone separator was obtained. The results show that: when the grid number of calculation domain reach 860000, it can cater to the calculation conditions of flow field, and the simulation results can agree with the experimental data better and will hardly change with the grid number; On the basis of standard k-ε model, the numerical simulation scheme was formulated by the orthogonal experiment method, through the comparison of results, the best combinations are 2 and 11; Applying the optimized combination to RNG k-ε model, Realizable k-ε model and RSM model and comparing simulation results with the existing one show that RSM was the ideal model used in simulation; With the change of the flow rate came a resistance characteristic curve of cyclone separator. The comparison between it and the predicted results of existing empirical formula of resistance characteristic drew the numerical simulation result, which is closest to Dirgo empirical formula; the first and second order upwind form have certain influence on the numerical simulation results, but the second one is more accurate in terms of simulating and predicting the parameters distribution inside flow field. This research result has certain reference value for cyclone separator design and performance optimization.

Numerical Simulation of Explosion in a Confined Box-Shaped Structure

2013 ◽  
Vol 671-674 ◽  
pp. 3204-3207
Author(s):  
Fan Yang ◽  
Li He ◽  
Xiao Liu ◽  
Bin Jia
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Load Distribution ◽  
Time History ◽  
Experimental Results ◽  
Blast Load ◽  
Propagation Law ◽  
Box Structure ◽  
Simulation Results ◽  
Good Agreement

In order to study the propagation law of shock wave and blast load distribution when an interior explosion occur in a box structure, a numerical simulation of an interior explosion within a box-shaped structure is presented in this paper using LS-DYNA. Overpressure-time history curve of the blast load at the measured points is obtained by numerical simulation, and compared with the experimental results. Numerical simulation results and experimental results are in good agreement. The results show that the blast wave reflected and superimposed many times in the box-shaped structure. When TNT is located in the center of the box-shaped structure, the center and the corner of the wall suffered the maximum overpressure.

Cavitation in Negative-pressure Microcapillary Devices with Tapered Constrictions: Experiment and Numerical Simulation

2012 ◽  
Vol 13 (5) ◽  
Author(s):  
Xing Yang ◽  
Jiang Li ◽  
Haosheng Chen
Keyword(s):  
Numerical Simulation ◽  
Negative Pressure ◽  
Atmospheric Pressure ◽  
Microfluidic Devices ◽  
Cavitation Number ◽  
Experimental Results ◽  
Positive Pressure ◽  
Pressure System ◽  
Recirculation Flow ◽  
Simulation Results

AbstractMicrocapillary devices with tapered constrictions were fabricated for the study of the features of the cavitation. The cavitation was induced by applying negative pressure at the outlet with opening the inlet to atmospheric pressure, and the experimental results show that the cavitation bubbles generated at the center of the tapered tip flow upstream and adhere on the wall near the orifice, which is explained by the recirculation flow according to the numerical simulation results. The desinent cavitation number keeps constant for a microcapillary device, and the device works in a negative-pressure system is more susceptible to the cavitation than that works in a positive-pressure system. In addition, the effect of the orifice size on the incipient cavitation number and the desinent cavitation number has been studied with five devices with different sizes of the orifices from 50 to 120 microns. Both the incipient and desinent cavitation numbers increase monotonely with the size of the orifice. These results may be helpful to the design of the geometries of the microfluidic devices for various applications.

Avalanche Features in Silicon Schottky-FETs in Accordance with Numerical Simulation Results

2006 ◽  
Vol 65 (16) ◽  
pp. 1533-1546
Author(s):  
Yu. Ye. Gordienko ◽  
S. A. Zuev ◽  
V. V. Starostenko ◽  
V. Yu. Tereshchenko ◽  
A. A. Shadrin
Keyword(s):  
Numerical Simulation ◽  
Simulation Results

NUMERICAL SIMULATION OF THE COMPACTION EFFECT DURING SHOCK WAVE € PARTICLE LAYER NUMERICAL SIMULATION OF THE COMPACTION EFFECT DURING SHOCK WAVE-PARTICLE LAYER INTERACTION

2020 ◽  
Author(s):  
YA. E. POROSHYNA ◽  
◽  
P. S. UTKIN ◽  
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Dust Explosion ◽  
Dense Particle ◽  
Layer Interaction ◽  
Particle Layer ◽  
Complex Process ◽  
Impermeable Wall

The problem of shock wave - dense particle layer interaction is a fundamental basis for the study of a more complex process of dust explosion or dust-layered detonation. The work presents results of numerical simulation of the experiment on interaction of an SW with particles layer deposited on the impermeable wall.

Tail shapes lead to different propulsive mechanisms in the body/caudal fin undulation of fish

2020 ◽  
pp. 095440622096768
Author(s):  
Jialei Song ◽  
Yong Zhong ◽  
Ruxu Du ◽  
Ling Yin ◽  
Yang Ding
Keyword(s):  
Numerical Simulation ◽  
Aspect Ratio ◽  
High Efficiency ◽  
The Body ◽  
Caudal Fin ◽  
Fish Model ◽  
Swimming Efficiency ◽  
Simulation Results ◽  
Propulsive Mechanism ◽  
High Depth

In this paper, we investigate the hydrodynamics of swimmers with three caudal fins: a round one corresponding to snakehead fish ( Channidae), an indented one corresponding to saithe ( Pollachius virens), and a lunate one corresponding to tuna ( Thunnus thynnus). A direct numerical simulation (DNS) approach with a self-propelled fish model was adopted. The simulation results show that the caudal fin transitions from a pushing/suction combined propulsive mechanism to a suction-dominated propulsive mechanism with increasing aspect ratio ( AR). Interestingly, different from a previous finding that suction-based propulsion leads to high efficiency in animal swimming, this study shows that the utilization of suction-based propulsion by a high- AR caudal fin reduces swimming efficiency. Therefore, the suction-based propulsive mechanism does not necessarily lead to high efficiency, while other factors might play a role. Further analysis shows that the large lateral momentum transferred to the flow due to the high depth of the high- AR caudal fin leads to the lowest efficiency despite the most significant suction.

scholarly journals Experiment and simulation about the effect of wear-ring abrasion on the performance of a marine centrifugal pump

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199811
Author(s):  
Wu Xianfang ◽  
Du Xinlai ◽  
Tan Minggao ◽  
Liu Houlin
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Pressure Pulsation ◽  
Vibration Velocity ◽  
Test Results ◽  
Obvious Effect ◽  
Performance Change ◽  
Pump Test ◽  
Simulation Results ◽  
Axis Passing

The wear-ring abrasion can cause performance degradation of the marine centrifugal pump. In order to study the effect of front and back wear-ring clearance on a pump, test and numerical simulation were used to investigate the performance change of a pump. The test results show that the head and efficiency of pump decrease by 3.56% and 9.62% respectively at 1.0 Qd due to the wear-ring abrasion. Under 1.0 Qd, with the increase of the front wear-ring the vibration velocity at pump foot increases from 0.4 mm/s to 1.0 mm/s. The axis passing frequency (APF) at the measuring points increases significantly and there appears new characteristic frequency of 3APF and 4APF. The numerical simulation results show that the front wear-ring abrasion affects the flow at the inlet of the front chamber of the pump and impeller passage. And the back wear-ring abrasion has obvious effect on the flow in the back chamber of the pump and impeller passage, while the multi-malfunction of the front wear-ring abrasion and back wear-ring abrasion has the most obvious effect on the flow velocity and flow stability inside pump. The pressure pulsation at Blade Passing Frequency (BPF) of the three schemes all decrease with the increase of the clearance.

Visualization of separation and reattachment in an incident shock-induced interaction

2021 ◽  
pp. 095441002098349
Author(s):  
Yun Jiao ◽  
Chengpeng Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shear Stress ◽  
Separation Bubble ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Bottom Wall ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Oil Flow

An experimental study is conducted on the qualitative visualization of the flow field in separation and reattachment flows induced by an incident shock interaction by several techniques including shear-sensitive liquid crystal coating (SSLCC), oil flow, schlieren, and numerical simulation. The incident shock wave is generated by a wedge in a Mach 2.7 duct flow, where the strength of the interaction is varied from weak to moderate by changing the angle of attack α of the wedge from 8° and 10° to 12°. The stagnation pressure upstream was set to approximately 607.9 kPa. The SSLCC technique was used to visualize the surface flow characteristics and analyze the surface shear stress fields induced by the initial incident shock wave over the bottom wall and sidewall experimentally which resolution is 3500 × 200 pixels, and the numerical simulation was also performed as the supplement for a clearer understanding to the flow field. As a result, surface shear stress over the bottom wall was visualized qualitatively by SSLCC images, and flow features such as separation/reattachment and the variations of position/size of separation bubble with wedge angle were successfully distinguished. Furthermore, analysis of shear stress trend over the bottom wall by a hue value curve indicated that the relative magnitude of shear stress increased significantly downstream of the separation bubble compared with that upstream. The variation trend of shear stress was consistent with the numerical simulation results, and the error of separation position was less than 2 mm. Finally, the three-dimensional schematic of incident shock-induced interaction has been achieved by qualitative summary by multiple techniques, including SSLCC, oil flow, schlieren, and numerical simulation.

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