scholarly journals Comparation of Effects Generated by Shock Waves of Selected Explosives

2014 ◽  
Vol 8 (2) ◽  
pp. 24-32
Author(s):  
Kamil Boc ◽  
Štefan Jangl ◽  
Dagmar Vidriková ◽  
Martin Vysocký
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Wave Effects ◽  
Explosive Device

Abstract Article deals with assessment of exactly acquired values of shock wave effects generated in the course of explosion of an explosive device and with comparation of the current options for determination of magnitude of their effect by the means of mathematic models using experimentally measured values.

scholarly journals Comparison of oblique shock wave angle in analytical and numerical solution

2019 ◽  
Vol 31 ◽  
pp. 137-142 ◽  
Author(s):  
Assen Marinov
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Wave Drag ◽  
Oblique Shock Wave ◽  
Friction Drag ◽  
Total Drag ◽  
Induced Drag ◽  
Drag And Lift ◽  
Wave Angle

The drag of the subsonic aircraft is largely formed by the skin friction drag and lift-induced drag. At transonic flight occurs shock wave. Determination of shock wave angle is important part of design of every aircraft, which working in supersonic airflow regimes. Formation of shock waves cause formation the wave drag. The wave drag could account about 35% from total drag of aircraft. Shock wave angle is directly linked with the intensity of itself. This work compares shock wave angle calculations using analytical and numerical solving methods.

scholarly journals ОСОБЛИВОСТІ ПРОЕКТУВАННЯ НОСКА ПОВІТРОЗАБІРНИКА ТУРБОВЕНТИЛЯТОРНОГО ДВИГУНА

2020 ◽  
pp. 25-36
Author(s):  
Владимир Федорович Шмырев
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Flow Separation ◽  
Sudden Change ◽  
Cross Sectional ◽  
Noise Absorption ◽  
Relevant Task ◽  
Air Intake ◽  
The Right

Optimization of turbofan engine air intake as well as geometry of intake lip, in-let cross-sectional area and its length is a relevant task in optimizing aerodynamic configuration of an aircraft. It is necessary to ensure a smooth entry of air flow into the engine at all modes of its operation and at various aircraft evolutions while minimizing impact on the overall aerodynamic efficiency of the aircraft. Development of engine air intake was once a very long, routine process that could last for months be-fore design completion, followed by expensive tests on determination of air intake performances on the engine test bench and in flight. Today, we can evaluate performances for a large number of air intake options using design software. The use of computational methods does not exclude tests of air intakes but dramatically reduces their quantity, testing costs and allows designers to focus mainly on the best candidates for air intakes avoiding potential surprises such as shock waves or flow separation caused by a shock wave. Optimal design of the air intake includes determining the right balance between the air intake characteristics, structural load and weight. An over-designed air intake will ultimately be overweight and thus more expensive in terms of flight cost. In a well-designed air intake the Mach number should not exceed 1, in order to avoid a sudden change in static pressure, temperature and density, which can lead to potential shock waves and flow separation caused by a shock wave in all areas throughout the flight. The use of computational fluid dynamics al-lows a better understanding of the conditions under which such adverse events occur. Adjacent to this task is the provision of necessary area on the inside of air intake to ensure sufficient noise absorption generated by the engine fan. The article considers evolution of research on the example of air intake of the D-436 engine of the An-148 aircraft.

Shock-wave effects arising from the earth's rotation

1968 ◽  
Vol 46 (8) ◽  
pp. 935-937
Author(s):  
David Davies
Keyword(s):  
Shock Wave ◽  
Angular Momentum ◽  
Shock Waves ◽  
The Other ◽  
Second Law ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Conservation Of Mass ◽  
Wave Effects ◽  
Newton's Second Law

The behavior of shock waves in the atmosphere is governed by eight independent equations. Four of these are the well-known Rankine–Hugoniot equations which express mass and momentum relationships. Two of the other equations, which both involve a Coriolis term, serve to describe the angular momentum relationships. The last two relate to development. All eight equations are derived from Newton's Second Law of Motion and the equation of conservation of mass.

scholarly journals Assessment of the Parameters of a Shock Wave on the Wall of an Explosion Cavity with the Refraction of a Detonation Wave of Emulsion Explosives

2021 ◽  
Vol 11 (9) ◽  
pp. 3976
Author(s):  
Pavel Igorevich Afanasev ◽  
Khairullo Faizullaevich Makhmudov
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Detonation Wave ◽  
Cavity Wall ◽  
Emulsion Explosives ◽  
Explosion Products ◽  
Wave Refraction ◽  
Wave Parameters ◽  
Jouguet Point

At present, studying the parameters of shock waves at pressures up to 20 GPa entails a number of practical difficulties. In order to describe the propagation of shock waves, their initial parameters on the wall of the explosion cavity need to be known. With the determination of initial parameters, pressures in the near zone of the explosion can be calculated, and the choice of explosives can be substantiated. Therefore, developing a method for estimating shock wave parameters on an explosion cavity wall during the refraction of a detonation wave is an important problem in blast mining. This article proposes a method based on the theory of breakdown of an arbitrary discontinuity (the Riemann problem) to determine the shock wave parameters on the wall of the explosion cavity. Two possible variants of detonation wave refraction on the explosion cavity wall are described. This manuscript compares the parameters on the explosion cavity wall when using emulsion explosives with those obtained using cheap granular ANFO explosives. The detonative decomposition of emulsion explosives is also considered, and an equation of state for gaseous explosion products is proposed, which enables the estimation of detonation parameters while accounting for the incompressible volume of molecules (covolume) at the Chapman–Jouguet point.

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.

Shock wave effects during a Taylor test

2006 ◽  
Vol 134 ◽  
pp. 1065-1070
Author(s):  
E. Lach ◽  
M. Scharf
Keyword(s):  
Shock Wave ◽  
Taylor Test ◽  
Wave Effects

Use of non-contrast computed tomography determined urinary stone fragility in predicting the outcome of extracorporeal shockwave lithotripsy treatment: a single-center study

2020 ◽  
Vol 14 (2) ◽  
pp. 59-63
Author(s):  
Athar Hameed ◽  
Khazir Hayyat Gondal
Keyword(s):  
Shock Waves ◽  
Renal Stone ◽  
Plain Film ◽  
Renal Stones ◽  
Renal Calculus ◽  
Urinary Stone ◽  
Stone Disease ◽  
Urinary Stones ◽  
Fisher Exact Test

Background: Renal stones represent a common urological pathology where standard treatment advised is ESWL in current practice. However, NCCT based determination of stone fragility may help to predict the outcome of ESWL treatment, hence optimizing its clinical use. Therefore, this study evaluated the role of NCCT determined urinary stone fragility in predicting the outcome of ESWL treatment in local clinical settings. Patients and methods: One hundred patients with single renal calculus of 0.6-2 cm in size were included. NCCT based determination of stone fragility in HU units was done for all patients. Patients were then subjected to ESWL, with a maximum of 3000 shock waves given per ESWL session. Plain film and/or ultrasonography was used to monitor ESWL treatment progress with a final NCCT evaluation at 12 weeks to determine the clearance of the calculi for each patient. Association of NCCT based stone fragility and outcome of ESWL was statistically analyzed using Fisher exact test. Results: The mean age of the patients was 37.7 ± 10.9 years with 54% being male. Decreasing stone fragility on NCCT (high = <500HU, moderate = 500-1000HU, and high = 1000HU) required more number and intensity of ESWL sessions (1-2 visits and 3000-6000 shock waves for high stone fragility group, 3-5 visits and 7000-18000 shock waves for the moderate group, and 6 visits and >18000 shock waves for low fragility group, respectively) necessary for clearance of urinary stones (p<0.001). In 98% of patients, the clearance of urinary stones was excellent. Conclusion: Renal stone patients with NCCT determined high and moderate stone fragility show an optimal response after ESWL treatment, whereas, for low fragility renal stones attenuative treatment like percutaneous nephrolithotomy and/or ureteroscopy should be considered instead of ESWL. This approach can enable patient stratification before ESWL therapy ensuring better clinical management of the renal stone disease.

Features of spatial shock-wave flows in vapor-gas-liquid mixtures

2014 ◽  
Vol 10 ◽  
pp. 27-31
Author(s):  
R.Kh. Bolotnova ◽  
U.O. Agisheva ◽  
V.A. Buzina
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Shock Waves ◽  
Liquid Mixture ◽  
Liquid Mixtures ◽  
Pressure Vessels ◽  
Water Mixture ◽  
Two Dimensional ◽  
Nonstationary Processes ◽  
Two Phase

The two-phase model of vapor-gas-liquid medium in axisymmetric two-dimensional formulation, taking into account vaporization is constructed. The nonstationary processes of boiling vapor-water mixture outflow from high-pressure vessels as a result of depressurization are studied. The problems of shock waves action on filled by gas-liquid mixture volumes are solved.

scholarly journals Nematic Dispersive Shock Waves from Nonlocal to Local

2021 ◽  
Vol 11 (11) ◽  
pp. 4736
Author(s):  
Saleh Baqer ◽  
Dimitrios J. Frantzeskakis ◽  
Theodoros P. Horikis ◽  
Côme Houdeville ◽  
Timothy R. Marchant ◽  
...  
Keyword(s):  
Shock Wave ◽  
Liquid Crystals ◽  
Shock Waves ◽  
Numerical Solutions ◽  
Wave Structure ◽  
Beam Power ◽  
Input Beam ◽  
Shock Wave Structure ◽  
Wave Solutions ◽  
Modulation Theory

The structure of optical dispersive shock waves in nematic liquid crystals is investigated as the power of the optical beam is varied, with six regimes identified, which complements previous work pertinent to low power beams only. It is found that the dispersive shock wave structure depends critically on the input beam power. In addition, it is known that nematic dispersive shock waves are resonant and the structure of this resonance is also critically dependent on the beam power. Whitham modulation theory is used to find solutions for the six regimes with the existence intervals for each identified. These dispersive shock wave solutions are compared with full numerical solutions of the nematic equations, and excellent agreement is found.

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