Shock wave propagation in non-uniform gas mixtures

2011 ◽  
Vol 226 (2) ◽  
pp. 123-130
Author(s):  
J Falcovitz ◽  
O Igra ◽  
D Igra
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Tube ◽  
Mass Fraction ◽  
Molar Fraction ◽  
Gaseous Mixture ◽  
Linear Distribution ◽  
Wave Patterns ◽  
Driver Section ◽  
Shock Tube Experiment

We consider a classical shock tube with Helium-filled driver section, and a driven section filled with a He– Ar gaseous mixture of continuously varying composition. We simulate a shock tube experiment, where the driven section composition starts out with pure Ar and ends with pure He (denoted ‘ − ’), or vice versa (denoted ‘+’). The initial pressures are 2 and 0.01 MPa. Two alternate initial species compositions are assumed: ‘Molar fraction’ – a linear distribution of the molar fraction; ‘Mass Fraction’ – a linear distribution of the mass fraction. Wave patterns arising in every case are presented and discussed.

Development of Shock-Wave-Powered Actuators for High Speed Positioning

2011 ◽  
Vol 5 (6) ◽  
pp. 786-792 ◽  
Author(s):  
Akira Kotani ◽  
◽  
Toshiharu Tanaka ◽  
Atsushi Fujishiro ◽  
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
High Speed ◽  
Initial Conditions ◽  
Reflected Shock Wave ◽  
Compressive Wave ◽  
Reflected Shock ◽  
Temperature And Pressure ◽  
Driver Section ◽  
End Wall

A shock wave is a compressive wave which propagates at supersonic speed. A shock wave is generated by the emission of energy for a very short duration by high speed phenomena, such as explosions, discharges, collisions, high speed flights, etc. Shock tube experiments have played an important role in the field of high speed gas dynamics. A shock tube is usually divided by a diaphragm into a driver section and a driven section. Generally, the initial conditions of the driver and driven sections are high and low pressure, respectively. When the diaphragm breaks, a shock wave is generated in the driven section. The density, temperature and pressure of the gas behind the shock wave rise discontinuously. The shock wave arrives at the end wall of the tube, and a reflected shock wave is generated by the reflection from the wall. The quantities behind the reflected shock wave rise further. If the shock wave can be generated continuously without the diaphragm needing to be changed, this phenomenon could possibly be applied to an actuator having a piston that moves at high speed. In this study, equipment powered by a shock wave is produced, and its performance is examined. The results show that piston movement generated by a shock wave is faster than that which is not and that the piston speeds depend on the initial conditions. Also, the characteristic of the actuator powered by the shock wave is revealed.

Analysis of shock-wave propagation in aqueous foams using shock tube experiments

2015 ◽  
Vol 27 (5) ◽  
pp. 056101 ◽  
Author(s):  
G. Jourdan ◽  
C. Mariani ◽  
L. Houas ◽  
A. Chinnayya ◽  
A. Hadjadj ◽  
...  
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Tube ◽  
Shock Wave Propagation ◽  
Aqueous Foams

scholarly journals Experimental and Numerical Investigation of the Mechanism of Blast Wave Transmission Through a Surrogate Head

2014 ◽  
Vol 9 (3) ◽  
Author(s):  
Yi Hua ◽  
Praveen Kumar Akula ◽  
Linxia Gu ◽  
Jeff Berg ◽  
Carl A. Nelson
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Numerical Model ◽  
Shock Tube ◽  
Blast Wave ◽  
Wave Transmission ◽  
Surface Strain ◽  
Transmission Mechanisms ◽  
Blast Wave Propagation ◽  
The Brain

This work is to develop an experiment-validated numerical model to elucidate the wave transmission mechanisms through a surrogate head under blast loading. Repeated shock tube tests were conducted on a surrogate head, i.e., water-filled polycarbonate shell. Surface strain on the skull simulant and pressure inside the brain simulant were recorded at multiple locations. A numerical model was developed to capture the shock wave propagation within the shock tube and the fluid-structure interaction between the shock wave and the surrogate head. The obtained numerical results were compared with the experimental measurements. The experiment-validated numerical model was then used to further understand the wave transmission mechanisms from the blast to the surrogate head, including the flow field around the head, structural response of the skull simulant, and pressure distributions inside the brain simulant. Results demonstrated that intracranial pressure in the anterior part of the brain simulant was dominated by the direct blast wave propagation, while in the posterior part it was attributed to both direct blast wave propagation and skull flexure, which took effect at a later time. This study served as an exploration of the physics of blast-surrogate interaction and a precursor to a realistic head model.

Study on Drug Powder Acceleration in a Micro Shock Tube

2015 ◽  
Author(s):  
Guang Zhang ◽  
Heuy Dong Kim ◽  
Yingzi Jin ◽  
Toshiaki Setoguchi
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Tube ◽  
Gas Flow ◽  
Stokes Equations ◽  
Supersonic Nozzle ◽  
Particle Diameter ◽  
Shock Wave Propagation ◽  
Finite Volume Scheme ◽  
Discrete Phase Model

Recently, needle-free drug delivery systems have been widely used for delivering drug particles into human body without any external needles in medical fields. Drug powders should be accelerated to obtain enough momentum to be delivered into the suitable layer of the skin. This is achieved by accelerating drug particles in a Contoured Shock Tube (CST) which consists of a micro shock tube and an expanded supersonic nozzle. Shock wave happens in micro shock tube, and supersonic flow with particles is induced by the shock wave and accelerated in the expanded nozzle. Even though micro shock tubes have been studied for a long time, detailed experimental data for shock waves and particle-gas flows are sparse to date and it is very important to investigate the complicated particle-gas flow fields for practical applications. In the present study, Particle Tracking Velocimetry (PTV) was used to measure the average velocity of the gas-particle flow behind the propagating shock wave. Unsteady flow properties and shock wave propagation were analyzed by this instantaneous particle velocity fields. Numerical simulation was performed with unsteady compressible Naver-stokes equations which were solved by using a fully implicit finite volume scheme. Discrete Phase Model (DPM) has been used for simulating particle-gas two-phase flows. Different particle diameter and density were performed in present numerical studies. Unsteady particle-gas flow characteristics and shock wave propagation have been studied and analyzed in details in present micro shock tube model.

Theory for producing a single-phase rarefaction shock wave in a shock tube

2001 ◽  
Vol 445 ◽  
pp. 37-54 ◽  
Author(s):  
S. H. FERGASON ◽  
T. L. HO ◽  
B. M. ARGROW ◽  
G. EMANUEL
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Shock Tube ◽  
Single Phase ◽  
Van Der Waals ◽  
Small Region ◽  
Incident Flow ◽  
Global Theory ◽  
Rarefaction Shock ◽  
Shock Tube Experiment

Although predicted early in the 20th century, a single-phase vapour rarefaction shock wave has yet to be demonstrated experimentally. Results from a previous shock tube experiment appear to indicate a rarefaction shock wave. These results are discussed and their interpretation challenged. In preparation for a new shock tube experiment, a global theory is developed, utilizing a van der Waals fluid, for demonstrating a single-phase vapour rarefaction shock wave in the incident flow of the shock tube. The flow consists of four uniform regions separated by three constant-speed discontinuities: a rarefaction shock, a compression shock, and a contact surface. Entropy jumps and upstream supersonic Mach number conditions are verified for both shock waves. The conceptual van der Waals model is applied to the fluid perfluoro-tripentylamine (FC-70, C15F33N) analytically, and verified with computational simulations. The analysis predicts a small region of initial states that may be used to unequivocally demonstrate the existence of a single-phase vapour rarefaction shock wave. Simulation results in the form of representative sets of thermodynamic state data (pressure, density, Mach number, and fundamental derivative of gas dynamics) are presented.

Computational Comparison of Shock Wave Propagation in Explosive Blast and Shock Tube Experiments

2013 ◽  
Author(s):  
Kaveh Laksari ◽  
Soroush Assari ◽  
Kurosh Darvish
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Shock Tube ◽  
Mechanical Behavior ◽  
Equations Of State ◽  
Shock Wave Propagation ◽  
Published Data ◽  
Fe Model ◽  
Temple University ◽  
Computational Comparison

In this study, detonation of TNT was simulated using an FE code and the resulting mechanical behavior of air, in which the explosion took place, was studied as a function of distance. Incident and reflected pressure and impulse profiles were compared with published data. In addition, an FE model of a shock tube setup at Temple University was developed using equations of state for Helium and air as the driver and driven fluids. The characteristics of the shock wave developed from explosive blast and shock tube were compared. It was shown that merely the two variables commonly used in the literature to compare the results from a shock tube to that of blast, i.e., peak incident pressure and positive duration, could not thoroughly include all the characteristics of the shock wave. Other parameters such as reflected pressure and impulse, which includes the velocity of the particles in addition to the pressure, are also needed to describe the shock wave.

Numerical Modelling of Shock-Wave Propagation in a Shock Tube Filled with Aqueous Foam

2015 ◽  
pp. 1511-1516
Author(s):  
D. Counilh ◽  
E. Del Prete ◽  
A. Chinnayya ◽  
A. Hadjadj ◽  
N. Rambert ◽  
...  
Keyword(s):  
Shock Wave ◽  
Wave Propagation ◽  
Numerical Modelling ◽  
Shock Tube ◽  
Shock Wave Propagation ◽  
Aqueous Foam
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