scholarly journals Effects of Reversed Shock Waves on Operation Mode in H2/O2 Rotating Detonation Chambers

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8296
Author(s):  
Yanliang Chen ◽  
Xiangyang Liu ◽  
Jianping Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Operation Mode ◽  
Wave Number ◽  
Mode Switching ◽  
Rotating Waves ◽  
Operation Modes ◽  
Rotating Detonation

Operation modes are an important topic in the research of Rotating Detonation Chamber (RDC) as it can affect the stability of RDC. However, they have not been discussed in detail due to the limitation of measurement means in experiments. The aim of this research is to investigate the mechanism of different operation modes by numerical simulation. In this paper, a numerical simulation for RDCs with separate injectors is carried out. Different operation modes and mode switching are analyzed. There is a series of reversed shock waves in the flow field. It was found that they have great effects on operation mode and mode switching in RDCs. A reversed shock wave can transit into a detonation wave after passing through isolated fresh gas region where fresh gas and burnt gas distribute alternatively. This shock-to-detonation transition (SDT) phenomenon will influence the ignition process, contra-rotating waves mode and mode switching in RDCs. SDT makes the number of detonation wave increases, resulting in multi-wave mode with one ignition. Moreover, quenching of detonation waves after collision and SDT after passing through isolated fresh gas region are the mechanism of contra-rotating waves mode in RDCs with separate injectors. In addition, when the inlet total temperature increases, a shock wave is easier to transit into a detonation wave. The distance that a shock wave travels before SDT decreases when temperature increases. This will result in mode switching. Therefore, SDT determines that there is a lower bound of detonation wave number.

Research on Propagation Numerical Simulation of Blast Shock Waves in Subway Station

2013 ◽  
Vol 380-384 ◽  
pp. 1725-1728
Author(s):  
Yang Hu ◽  
Huai Yu Kang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Experimental Study ◽  
Shock Waves ◽  
Theoretical Basis ◽  
Damage Effect ◽  
Subway Station ◽  
Element Calculation ◽  
Dynamic Finite Element ◽  
Walking Pattern

In this paper, we Research on Propagation Numerical Simulation and damage effect of Blast Shock Waves in Subway Station by using LS-DYNA dynamic finite element calculation program , the results reproduce the formation process of the explosive flow field, and analysis the shock wave waveform, attenuation and walking pattern, provides the theoretical basis for further experimental study.

On Generation of Ultra-High Pressure by Converging of Underwater Shock Waves

1998 ◽  
Vol 120 (1) ◽  
pp. 51-55 ◽  
Author(s):  
S. Itoh ◽  
S. Kubota ◽  
S. Nagano ◽  
M. Fujita
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Simulation Method ◽  
Ceramic Materials ◽  
Underwater Shock Wave ◽  
Water Chamber ◽  
Metallic Compounds ◽  
Underwater Shock ◽  
Graph System

The characteristics of a new assembly for the shock consolidation of difficult-to-consolidate powders, such as inter-metallic compounds or ceramic materials, were investigated by both the experimental method and numerical simulation method. The assembly consists of an explosive container, a water chamber, and a powder container. Once the explosive is detonated, a detonation wave occurs and propagates, and then impinges on the water surface of the water chamber. After that, there occurs immediately an underwater shock wave in the water chamber. The underwater shock wave interacts with the wall of the chamber during its propagation so that its strength is increased by the converging effect. We used the usual shadow graph system to photograph the interaction process between detonation wave and water. We also used a Manganin piezoresistance gage to measure the converged pressure of the conical water chamber. Finally, we numerically investigated, in detail, the converging effects of the various conical water chambers on the underwater shock waves. The experimental results and the correspondingly numerical results agree quite well with each other.

scholarly journals Explosion waves and shock waves III-The initiation of detonation in mixtures of ethylene and oxygen and of carbon monoxide and oxygen

1935 ◽  
Vol 152 (876) ◽  
pp. 418-445 ◽  
Author(s):  
William Payman ◽  
H. Titman ◽  
Jocelyn Field Thorpe
Keyword(s):  
Shock Wave ◽  
Carbon Monoxide ◽  
Shock Waves ◽  
Detonation Wave ◽  
Wave Speed ◽  
Gas Mixtures ◽  
Gas Mixture ◽  
And Shock Waves ◽  
Long Run ◽  
Detonating Gas

This series of papers has so far dealt mainly with non-maintained or partially maintained atmospheric shock waves, and only incidentally with the fully maintained "detonation" wave. It is generally accepted that the detonation wave in an explosive gas mixture is a shock wave produced by the rapid combustion of the mixture, sufficiently intense to cause almost instantaneous ignition of the gas through which it passes, and continuous maintained by the combustion thereby started. An account of some preliminary experiments, using the "wave-speed" camera to record the movement of the flame and of the invisible shock waves in front of the flame in gas mixtures prior to detonation, has already been given by one of us. Those experiments related mainly to hydrogen-oxygen and methane-oxygen mixtures whose aptitude to detonate may be regarded as moderate, for the continuation of the work, mixtures with oxygen have again been used, but a more readily detonating gas, ethylene, was chosen. Experiments were also made with carbon monoxide, because the flame usually requires a comparatively long run before detonation is established. These two gases have the advantage, not shared by hydrogen and methane, that their predetonation flames are sufficiently actinic for good records to be obtained by direct photography for comparison with corresponding "wave-speed" records. All gas mixtures used were saturated with water vapour.

Induction of Microdamage Through Application of Acoustic Energy to Cortical Bone

2004 ◽  
Author(s):  
Andrea E. Tami ◽  
Melissa L. Knothe Tate ◽  
Jamie R. Streem ◽  
Ryan S. Comisford ◽  
Jared M. O’Leary ◽  
...  
Keyword(s):  
Shock Wave ◽  
Confocal Microscopy ◽  
Shock Waves ◽  
Bone Turnover ◽  
Cortical Bone ◽  
Kidney Stones ◽  
Acoustic Energy ◽  
Wave Number ◽  
Extracorporeal Shock Waves ◽  
Naturally Occurring

Extracorporeal shock waves (ESW) are used routinely to break up kidney stones. Recently ESW has been implemented in the orthopaedic arena to treat heel spurs, although the mechanism underlying this therapeutic effect is not known. Acoustic energy has been shown to increase transport in bone. Furthermore, naturally occurring microdamage in bone has been implicated as a trigger for the onset of remodeling. We hypothesize that controlled application of ESW to bone tissue increases transport and stimulates bone turnover through production of low-level microdamage. The goal of this study was to identify the bandwidth and the application regime of acoustic energy to produce such damage. Transverse sections of sheep metacarpi (1 cm) were subjected to acoustic loading regimes of varying shock wave number and intensity. Thereafter, the blocks were bulk-stained with procion dye, embedded in PMMA, and sectioned into 100 mm slices for confocal microscopy and analysis. The blocks loaded with the highest energy regimes showed marked diffuse microdamage and microcracks, usually at sites of discontinuity along the periosteal edge. These results provide a first step in testing our hypothesis and ultimately may provide a basis for the exploitation of ESW to prevent osteopenia and/or osteoporosis.

Implementation of Seamless Switching of Micro-Grid Operation Mode Based on Multi-Agent System

2013 ◽  
Vol 448-453 ◽  
pp. 2583-2589
Author(s):  
Zhi Wen Liu ◽  
Wen Bo Xia
Keyword(s):  
Control System ◽  
Operation Mode ◽  
Control Level ◽  
Switching Control ◽  
Mode Switching ◽  
Short Time Scale ◽  
Operation Modes ◽  
Multi Agent ◽  
Micro Grid ◽  
Grid Operation

Switching control of micro-grid operation modes belongs to short time scale control level, this paper proposes three-tier structure of micro-grid energy management system suitable for switching control of micro-grid operation modes on the basis of the analysis of micro-grid operation mode switching requirements for the control system, and builds micro-grid central control system based on multi-agent technology aiming at the coordinated control of micro-grid operation mode switching, which will effectively enhance the implementation effect of switching control strategy, and play important role in achieving the seamless switching control of micro-grid operation modes.

scholarly journals Physics and applications with laser-induced relativistic shock waves

2016 ◽  
Vol 4 ◽  
Author(s):  
S. Eliezer ◽  
J. M. Martinez-Val ◽  
Z. Henis ◽  
N. Nissim ◽  
S. V. Pinhasi ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Bulk Material ◽  
High Irradiance ◽  
Alpha Particles ◽  
Relativistic Shock ◽  
Laser Acceleration ◽  
The Creation ◽  
Special Case

The laser-induced relativistic shock waves are described. The shock waves can be created directly by a high irradiance laser or indirectly by a laser acceleration of a foil that collides with a second static foil. A special case of interest is the creation of laser-induced fusion where the created alpha particles create a detonation wave. A novel application is suggested with the shock wave or the detonation wave to ignite a pre-compressed target. In particular, the deuterium–tritium fusion is considered. It is suggested that the collision of two laser accelerated foils might serve as a novel relativistic accelerator for bulk material collisions.

Investigation on the Protection of the End Cover of the Cylindrical Containment Vessel

2019 ◽  
Author(s):  
Liucheng Zhang ◽  
Qi Dong ◽  
Sha Yang ◽  
Jiahe Feng ◽  
Rongxi Hu
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shock Waves ◽  
Energy Absorption ◽  
Aluminum Foam ◽  
Containment Vessel ◽  
Negative Effect ◽  
Simulation And Experiment ◽  
The Impact

Abstract The cover of a cylindrical explosion containment vessel would suffer an extremely intense impact because the shock wave and blast products would converge at the cover area. To reduce the impact of shock waves to the cover, cases with aluminum foam placed at the end of the vessel and in the interior of the cylindrical portion are studied by numerical simulation and experiment. The result shows that aluminum foam located at the end of the vessel can have a great effect on the protection of the cover because it can absorb the energy of the shock wave that has spread to the end of the vessel. Aluminum foam located in the interior of the cylindrical portion would have a negative effect on the protection of the cover because it would reduce the distance between the charge and the cylindrical portion, the effect of which is more significant than the effect of energy absorption. These results can contribute to the design of cylindrical explosion containment vessels.

The initiation of condensed explosives by shock waves from metals

1958 ◽  
Vol 246 (1245) ◽  
pp. 284-288 ◽  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Mild Steel ◽  
Delay Time ◽  
Incident Shock ◽  
Shock Strength ◽  
Solid Explosive ◽  
Condensed Explosives

When a shock wave is transmitted from a metal to a solid explosive a pure shock wave is transmitted into the explosive. The shock generally builds up to a complete detonation wave but in some cases it fails to initiate the explosive. In the former case an effective delay time in the initiation of the explosive is observed. Initiation delays have been measured in 2 in. diam. sticks of 60/40 RDX/TNT as a function of incident shock strength in mild steel and aluminium .

scholarly journals Free Switching Control Strategy for Multi-Operation Modes of Multi-Port Energy Router in Distribution Area

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7860
Author(s):  
Shumei Chi ◽  
Zhipeng Lv ◽  
Lan Liu ◽  
Yang Shan
Keyword(s):  
Control Strategy ◽  
Power Supply ◽  
Operation Mode ◽  
Switching Control ◽  
Mode Switching ◽  
Distribution Area ◽  
Power Calculation ◽  
Operation Modes ◽  
New Energy ◽  
Switching Control Strategy

For the distribution area with a high penetration rate of new energy, the traditional power supply system has some problems, such as a single form of power supply and low utilization of new energy. Because the multi-port energy router can realize the interconnection and complementation of multiple energy forms, it has become the key piece of equipment in the hybrid AC/DC distribution area. Nevertheless, restricted by the existing control strategy, the performance of the energy router in complex operation mode switching and coordinated control still needs to be further improved. To address this issue, the free switching control strategy is proposed in this paper. Firstly, the topology and model of the multi-port energy router are designed and established. Secondly, the operation mode of the system is analyzed, and the control strategy of each port is designed. Then, a reference power calculation method suitable for multi-mode operation is derived. Based on this, the control strategy does not need to be changed when operation modes are switched. Furthermore, the extended state observer is introduced to track and compensate for the new energy disturbance, which can improve the power quality of the system. Finally, the simulation and experimental results show that the proposed control strategy of the multi-port energy router can realize flexible and controllable power transmission among various modules in the distribution area and the free switching of multi-operation modes without changing the control strategy.

scholarly journals Coordinated Control of Diesel Generators and Batteries in DC Hybrid Electric Shipboard Power System

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6246
Author(s):  
Luona Xu ◽  
Baoze Wei ◽  
Yun Yu ◽  
Josep M. Guerrero ◽  
Juan Vasquez
Keyword(s):  
Operation Mode ◽  
Power Sharing ◽  
Mode Switching ◽  
Maritime Industry ◽  
Power Sources ◽  
Operation Modes ◽  
Dc Bus ◽  
Hybrid Electric ◽  
Diesel Generators ◽  
Bus Voltage

Hybrid electric ships powered by diesel generators and batteries are the main configuration for shipboard microgrids (SMGs) in the current maritime industry. Extensive studies have been conducted for the hybrid operation mode, whereas the all-electric operation mode and the switching between the aforementioned two modes in a system with multiple generators and batteries have not been tested. In this paper, a coordinated approach for a hybrid electric ship is proposed, where two operation modes have been simultaneously considered. More specifically, for achieving an efficient operation with reduced generator wear losses, the governor-less diesel-engine-driven generators have been adopted in the study. According to the practical operation conditions, two operation modes, the all-electric and hybrid modes, are preset. Based on these, the coordination of the generators acting as the main power sources and batteries regulating the power flow and improving the generator efficiency is studied. The governor-less diesel generators are regulated to inject the rated power in order to maximize the generator efficiency, while the DC bus voltage is regulated by DC/DC converters. For the benefit of the overall lifespan of battery banks, power sharing during charging and discharging states have been realized by the state of charge (SoC)-based adaptive droop regulator. For the test of two operation modes, as well as the mode switching, a simulation assessment in a 1 kV DC SMG has been conducted. The simulation results show that the DC bus voltage can be controlled well, and that the power sharing among batteries follows the design. Additionally, smooth transients can be observed during mode switching when the proposed control scheme is applied.

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