Shock Wave (Atmospheric Entry)

2012 ◽  
Keyword(s):  
Shock Wave ◽  
Atmospheric Entry

RELAXATION PROCESSES BEHIND THE SHOCK WAVE IN AIR

2020 ◽  
Author(s):  
A. I. Bryzgalov ◽  
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
High Temperature ◽  
Space Missions ◽  
Relaxation Processes ◽  
Flow Conditions ◽  
Chemical Nonequilibrium ◽  
Atmospheric Entry ◽  
Qualitative And Quantitative ◽  
High Enthalpy

This work is relevant to numerical simulation of atmospheric entry phase of space missions and in high enthalpy facilities producting flow conditions close to flight conditions. Such flows are featured by low pressure and high temperature, which induces thermal and chemical nonequilibrium, while calculations with equilibrium assumption give both qualitative and quantitative errors.

Shock Wave (Atmospheric Entry)

2011 ◽  
pp. 1508-1509
Author(s):  
Henderson James Cleaves
Keyword(s):  
Shock Wave ◽  
Atmospheric Entry

On the capture of small stony asteroids into Earth orbit by atmospheric grazing

2021 ◽  
Author(s):  
Shujuan Geng ◽  
Binghong Zhou ◽  
Mingtao Li
Keyword(s):  
Shock Wave ◽  
Landing Site ◽  
Earth Orbit ◽  
Direct Impact ◽  
Impact Event ◽  
Mass Ratio ◽  
Time And Space ◽  
Atmospheric Entry

Abstract An Earth-grazing asteroid can be captured into a gravitational bound orbit around Earth during its transitory atmospheric journey. Otherwise, it will either escape back to space or plunge to Earth directly. With fragmentation taken into account, we subdivide the captured and direct impact modes, expanding the above three modes into five – escaping, captured impact with and without fragmentation, direct impact with and without fragmentation. We then investigate the conditions of those various impact modes of shallow-angle impacts of small stony asteroids no larger than 100 m in diameter. Moreover, the atmospheric entry processes of captured stony asteroids are further studied. Results show that asteroids with larger diameters are easier to fragment for less deceleration due to the smaller area-mass ratio, narrowing the corridor for capture. A captured asteroid can enter the atmosphere many times, highlighting itself by a series of explosive phenomena due to the shock wave it produced during every passage. The number of revolutions before its final entry increases as the theoretical perigee altitude rises. The multi-entry phenomenon of captured impact reduces the velocity and mass of the impactor and raises the possibility of an intact landing of the object via atmospheric dissipation. The time and space intervals between each entry make it difficult to identify whether the scattered impacts come from one captured impact event or just a series of different fireballs. The long path before its final hit also increases the difficulty of predicting the exact airburst position or landing site.

A new type of defect structure in 124-superconducting oxide revealed by HREM

1991 ◽  
Vol 49 ◽  
pp. 1092-1093
Author(s):  
R. Sharma ◽  
B.L. Ramakrishna ◽  
N.N. Thadhani ◽  
D. Hianes ◽  
Z. Iqbal
Keyword(s):  
Shock Wave ◽  
Defect Structure ◽  
Neutron Radiation ◽  
Weak Links ◽  
Defect Structures ◽  
New Materials ◽  
New Type ◽  
Current Densities ◽  
Processing Techniques ◽  
Microstructural Studies

After materials with superconducting temperatures higher than liquid nitrogen have been prepared, more emphasis has been on increasing the current densities (Jc) of high Tc superconductors than finding new materials with higher transition temperatures. Different processing techniques i.e thin films, shock wave processing, neutron radiation etc. have been applied in order to increase Jc. Microstructural studies of compounds thus prepared have shown either a decrease in gram boundaries that act as weak-links or increase in defect structure that act as flux-pinning centers. We have studied shock wave synthesized Tl-Ba-Cu-O and shock wave processed Y-123 superconductors with somewhat different properties compared to those prepared by solid-state reaction. Here we report the defect structures observed in the shock-processed Y-124 superconductors.

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

Electron microscopy study of shock synthesis of silicides

1993 ◽  
Vol 51 ◽  
pp. 1162-1163
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Close Contact ◽  
Microscopy Study ◽  
High Energy ◽  
Electron Microscopy Study ◽  
Powder Materials ◽  
Porous Powder ◽  
Wave Effects ◽  
Wave Passage

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

1264: Predictors of Shock-Wave Lithotripsy Success for Proximal Ureteral Calculi on Non-Contrast CT?

2007 ◽  
Vol 177 (4S) ◽  
pp. 417-417
Author(s):  
Eric A. Singer ◽  
Jared D. Christensen ◽  
Susan Messing ◽  
Erdal Erturk
Keyword(s):  
Shock Wave ◽  
Shock Wave Lithotripsy ◽  
Ureteral Calculi ◽  
Contrast Ct

1108: Treatment Strategy Improves the in Vivo Stone Comminution Efficiency and Reduces Renal Tissue Injury During Shock Wave Lithotripsy

2005 ◽  
Vol 173 (4S) ◽  
pp. 300-301
Author(s):  
Michaella E. Maloney ◽  
Pei Zhong ◽  
Charles G. Marguet ◽  
Yufeng F. Zhou ◽  
Jeffrey C. Sung ◽  
...  
Keyword(s):  
Shock Wave ◽  
Treatment Strategy ◽  
Shock Wave Lithotripsy ◽  
Tissue Injury ◽  
Renal Tissue
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