scholarly journals Refraction of detonation wave at interface between condensed explosives and high sound-speed material

2016 ◽  
Vol 65 (2) ◽  
pp. 024702
Author(s):  
Yu Ming ◽  
Liu Quan
Keyword(s):  
Detonation Wave ◽  
Sound Speed ◽  
Condensed Explosives ◽  
High Sound

scholarly journals Forbidden line diagnostics of photoevaporative disc winds

2020 ◽  
Vol 496 (3) ◽  
pp. 2932-2945 ◽  
Author(s):  
G Ballabio ◽  
R D Alexander ◽  
C J Clarke
Keyword(s):  
Sound Speed ◽  
Central Star ◽  
High Energy ◽  
Emission Lines ◽  
Limiting Factor ◽  
Line Profiles ◽  
Gas Temperature ◽  
Characteristic Emission ◽  
Extreme Uv ◽  
High Sound

ABSTRACT Photoevaporation driven by high-energy radiation from the central star plays an important role in the evolution of protoplanetary discs. Photoevaporative winds have been unambiguously detected through blue-shifted emission lines, but their detailed properties remain uncertain. Here we present a new empirical approach to make observational predictions of these thermal winds, seeking to fill the gap between theory and observations. We use a self-similar model of an isothermal wind to compute line profiles of several characteristic emission lines (in particular the [Ne ii] line at 12.81 μm, and optical forbidden lines such as [O i] 6300 Å and [S ii] 4068/4076 Å), studying how the lines are affected by parameters such as the gas temperature, disc inclinations, and density profile. Our model successfully reproduces blue-shifted lines with $v_{\rm peak} \lesssim 10$ km s−1, which decrease with increasing disc inclination. The line widths increase with increasing disc inclinations and range from $\Delta v\sim 15\text{ to }30$ km s−1. The predicted blue-shifts are mostly sensitive to the gas sound speed (and therefore the temperature). The observed [Ne ii] line profiles are consistent with a thermal wind and point towards a relatively high sound speed, as expected for extreme-UV photoevaporation. However, the observed [O i] line profiles require lower temperatures, as expected in X-ray photoevaporation, and show a wider scatter that is difficult to reconcile with a single wind model; it seems likely that these lines trace different components of a multiphase wind. We also note that the spectral resolution of current observations remains an important limiting factor in these studies, and that higher resolution spectra are required if emission lines are to further our understanding of protoplanetary disc winds.

Characterization of the Content of the Cavity Behind a High-Speed Supercavitating Body

2006 ◽  
Vol 129 (2) ◽  
pp. 136-145 ◽  
Author(s):  
Xiongjun Wu ◽  
Georges L. Chahine
Keyword(s):  
Sound Speed ◽  
High Speed ◽  
Test Facility ◽  
Direct Visualization ◽  
Acoustic Measurements ◽  
Supercavitating Flow ◽  
Flow Test ◽  
High Sound ◽  
Very High

A high speed/high flow test facility was designed and implemented to study experimentally the supercavitating flow behind a projectile nose in a controlled laboratory setting. The simulated projectile nose was held in position in the flow and the cavity interior was made visible by having the walls of the visualization facility “cut through” the supercavity. Direct visualization of the cavity interior and measurements of the properties of the cavity contents were made. Transducers were positioned in the test section within the supercavitation volume to enable measurement of the sound speed and attenuation as a function of the flow and geometry parameters. These characterized indirectly the content of the cavity. Photography, high speed videos, and acoustic measurements were used to investigate the contents of the cavity. A side sampling cell was also used to sample in real time the contents of the cavity and measure the properties. Calibration tests conducted in parallel in a vapor cell enabled confirmation that, in absence of air injection, the properties of the supercavity medium match those of a mixture of water vapor and water droplets. Such a mixture has a very high sound speed with strong sound attenuation. Injection of air was also found to significantly decrease sound speed and to increase transmission.

Ultrasound tomography of materials with high sound speed contrast

2017 ◽  
Vol 142 (4) ◽  
pp. 2537-2537
Author(s):  
Timothe Falardeau ◽  
Pierre Belanger
Keyword(s):  
Sound Speed ◽  
Ultrasound Tomography ◽  
High Sound

Validity of the Classical Detonation Wave Structure for Condensed Explosives

1968 ◽  
Vol 11 (7) ◽  
pp. 1473 ◽  
Author(s):  
Francis J. Petrone
Keyword(s):  
Detonation Wave ◽  
Wave Structure ◽  
Condensed Explosives

scholarly journals Acoustic Characterization of Fluorinert FC-43 Liquid with Helium Gas Bubbles: Numerical Experiments

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Christian Vanhille ◽  
Cristian Pantea ◽  
Dipen N. Sinha
Keyword(s):  
Sound Speed ◽  
Numerical Experiments ◽  
Underwater Acoustics ◽  
Gas Bubbles ◽  
Acoustic Characteristics ◽  
Parametric Generation ◽  
Acoustic Characterization ◽  
Helium Gas ◽  
High Sound

In this work, we define the acoustic characteristics of a biphasic fluid consisting of static helium gas bubbles in liquid Fluorinert FC-43 and study the propagation of ultrasound of finite amplitudes in this medium. Very low sound speed and high sound attenuation are found, in addition to a particularly high acoustic nonlinear parameter. This result suggests the possibility of using this medium as a nonlinear enhancer in various applications. In particular, parametric generation of low ultrasonic frequencies is studied in a resonator cavity as a function of driving pressure showing high conversion efficiency. This work suggests that this medium could be used for applications such as parametric arrays, nondestructive testing, diagnostic medicine, sonochemistry, underwater acoustics, and ultrasonic imaging and to boost the shock formation in fluids.

scholarly journals Dynamics of high sound-speed metal confiners driven by non-ideal high-explosive detonation

2015 ◽  
Vol 162 (5) ◽  
pp. 1857-1867 ◽  
Author(s):  
Mark Short ◽  
Scott I. Jackson
Keyword(s):  
Sound Speed ◽  
High Explosive ◽  
High Sound ◽  
Explosive Detonation

An Omnidirectional Transducer Design Attached with High Sound-Speed Material for Use in Deep Seas

1989 ◽  
Vol 28 (S1) ◽  
pp. 57
Author(s):  
Hiroyuki Hachiya ◽  
Shigeo Ohtsuki ◽  
Motoyoshi Okujima
Keyword(s):  
Sound Speed ◽  
Transducer Design ◽  
High Sound

Diameter Effect in Condensed Explosives. The Relation between Velocity and Radius of Curvature of the Detonation Wave

1954 ◽  
Vol 22 (11) ◽  
pp. 1920-1924 ◽  
Author(s):  
William W. Wood ◽  
John G. Kirkwood
Keyword(s):  
Detonation Wave ◽  
Radius Of Curvature ◽  
Condensed Explosives ◽  
Diameter Effect

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 .

The propagation of detonation waves in non-ideal condensed-phase explosives confined by high sound-speed materials

2013 ◽  
Vol 25 (8) ◽  
pp. 086102 ◽  
Author(s):  
Stefan Schoch ◽  
Nikolaos Nikiforakis ◽  
Bok Jik Lee
Keyword(s):  
Condensed Phase ◽  
Sound Speed ◽  
Detonation Waves ◽  
Condensed Phase Explosives ◽  
High Sound
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