scholarly journals Experiments in Shock-Vortex Interactions

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 303
Author(s):  
Beric Skews
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Shear Layer ◽  
Plane Shock ◽  
Vortex Interactions ◽  
The Past ◽  
Spiral Vortex ◽  
Diffracted Waves ◽  
Pressure Spike ◽  
Curved Shock Waves

Studies of shock-vortex interactions in the past have predominantly been numerical, with a number of idealizations such as assuming an isolated vortex and a plane shock wave. In the present case the vortex is generated from flow separation at a corner. A shear layer results which wraps up into a spiral vortex. The flow is impulsively initiated by the diffraction of a shock wave over the edge. The strength of the shock determines the nature of the flow at the corner and that induced behind the diffracted wave. A wide variety of cases are considered using different experimental arrangements such as having two independent shock waves arriving at the corner at different times, to reflecting the diffracting wave off different surfaces back into the vortex, and to examining the flow around bends where the reflection off the far wall reflects back onto the vortex. The majority of studies have shown that the vortex normally retains its integrity after shock transit. Some studies with curved shock waves and numerous traverses have shown evidence of vortex breakup and the development of turbulent patches in the flow, as well as significant vortex stretching. Depending on the direction of approach of the shock wave it refracts through the shear layer thereby changing the strength and direction of both. Of particular note is that the two diffracted waves which emerge from the vortex as the incident wave passes through interact with each other resulting in a pressure spike of considerable magnitude. An additional spike is also identified.

Effects of Shock Waves on Acceleration of Cell Growth Rate by Shock Tube

2008 ◽  
Author(s):  
Masaaki Tamagawa ◽  
Norikazu Ishimatsu
Keyword(s):  
Shock Wave ◽  
Growth Rate ◽  
Endothelial Cells ◽  
Shock Waves ◽  
Shock Tube ◽  
Test Case ◽  
Plane Shock ◽  
Extracorporeal Shock Wave ◽  
Shock Wave Pressure

This paper describes effects of shock waves on cells to certificate the angiogenesis by shock wave (pressure wave) in the clinical application such as ESW (Extracorporeal Shock Wave). Especially, to investigate the effects of shock waves on the endothelial cells in vitro, the cells worked by plane shock waves using shock tube apparatus are observed and measured in the microscope. The peak pressure working on the endothelial cells at the test case is 0.4 MPa. After working shock waves on suspended cells, growth rate (area per one cell and population of cells) are measured by image processing. It is found that the growth rate of the shock-worked cells from 0 to 4h is clearly high compared with control one. It is concluded that once shock waves worked, the cells have capacity to increase growth rate in vitro. This preliminary result will be applied to fundamental investigations about shock wave stimulus on several kinds of cells in future.

On the stability of plane shock waves

1957 ◽  
Vol 2 (4) ◽  
pp. 397-411 ◽  
Author(s):  
N. C. Freeman
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Shock Waves ◽  
Plane Shock ◽  
Two Dimensional ◽  
Small Perturbations ◽  
Diverging Channel ◽  
Maximum Stability ◽  
The Stability ◽  
Fourier Type

The decay of small perturbations on a plane shock wave propagating along a two-dimensional channel into a fluid at rest is investigated mathematically. The perturbations arise from small departures of the walls from uniform parallel shape or, physically, by placing small obstacles on the otherwise plane parallel walls. An expression for the pressure on a shock wave entering a uniformly, but slowly, diverging channel already exists (given by Chester 1953) as a deduction from the Lighthill (1949) linearized small disturbance theory of flow behind nearly plane shock waves. Using this result, an expression for the pressure distribution produced by the obstacles upon the shock wave is built up as an integral of Fourier type. From this, the shock shape, ξ, is deduced and the decay of the perturbations obtained from an expansion (valid after the disturbances have been reflected many times between the walls) for ξ in descending power of the distance, ζ, travelled by the shock wave. It is shown that the stability properties of the shock wave are qualitatively similar to those discussed in a previous paper (Freeman 1955); the perturbations dying out in an oscillatory manner like ζ−3/2. As before, a Mach number of maximum stability (1·15) exists, the disturbances to the shock wave decaying most rapidly at this Mach number. A modified, but more complicated, expansion for the perturbations, for use when the shock wave Mach number is large, is given in §4.In particular, the results are derived for the case of symmetrical ‘roof top’ obstacles. These predictions are compared with data obtained from experiments with similar obstacles on the walls of a shock tube.

Flow Changes in Gases in which Mass and Impulse are Conserved

1953 ◽  
Vol 4 (2) ◽  
pp. 193-204 ◽  
Author(s):  
L. G. Dawson
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
The Past ◽  
Constant Area ◽  
Before And After ◽  
Conservation Of Momentum ◽  
Total Temperature ◽  
Flow Changes ◽  
Quantity Of Heat ◽  
General Method

SummaryThis note discusses changes in the state of a gas flowing in a duct of constant area. In the past, changes, such as normal shock waves, combustion and other phenomena, which are defined by the equations of energy, conservation of momentum and mass flow, have each been treated on their merits. In this note a method is developed whereby all phenomena governed by these three equations can be solved by a single general method. The method rests on the derivation of a parameter which is unaltered in value by the change, in all cases where the total temperature is constant. A shock wave is an example of such a discontinuity. In problems of heat addition or extraction, the parameter changes its value only because of the change in total temperature. The change in total temperature may be calculated from the known quantity of heat added or extracted.The parameters derived are useful in showing how problems of this type should be attacked analytically. With oblique waves it is easy to derive a relation between the normal velocities before and after the wave, and it is probable that this relationship has not been published before.

Precursor shock waves at a slow—fast gas interface

1976 ◽  
Vol 76 (1) ◽  
pp. 157-176 ◽  
Author(s):  
A. M. Abd–El–Fattah ◽  
L. F. Henderson ◽  
A. Lozzi
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Shock Wave ◽  
Shock Waves ◽  
Plane Shock ◽  
One Dimensional ◽  
Irregular Wave ◽  
Irregular Systems ◽  
Theory And Experiment ◽  
Good Agreement

This paper presents experimental data obtained for the refraction of a plane shock wave at a carbon dioxide–helium interface. The gases were separated initially by a delicate polymer membrane. Both regular and irregular wave systems were studied, and a feature of the latter system was the appearance of bound and free precursor shocks. Agreement between theory and experiment is good for regular systems, but for irregular ones it is sometimes necessary to take into account the effect of the membrane inertia to obtain good agreement. The basis for the analysis of irregular systems is one-dimensional piston theory and Snell's law.

Simple Waves and Shock Waves Generated by an Incident Shock Wave in Two-Dimensional Hyperelastic Materials

1984 ◽  
Vol 51 (3) ◽  
pp. 586-594 ◽  
Author(s):  
Yongchi Li ◽  
T. C. T. Ting
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Energy Function ◽  
Strain Energy ◽  
Strain Energy Function ◽  
Incident Shock ◽  
Plane Shock ◽  
Developable Surface ◽  
Two Dimensional ◽  
Reflected Waves

The reflection of an oblique plane shock wave from a boundary in a two-dimensional isotropic hyperelastic material is studied. For plane strain deformations, the strain energy function W is a function of two invariants p and q of the deformation gradient. There are, in general, two reflected waves each of which can be a simple wave or a shock wave. For a special class of materials for which the strain energy function W(p, q) represents a developable surface (of which harmonic materials are particular examples), one of the reflected waves is always a shock wave. It is shown that there are materials other than harmonic materials for which the wave speeds are independent of the direction of propagation. Illustrative examples are presented to show how one can determine the reflected waves from a rigid boundary. It is also shown that for certain incident shock waves, there exists only one reflected wave.

Effects of Underwater Shock Wave on Endothelial Cells in Vitro Using Shock Tube

2007 ◽  
Author(s):  
Masaaki Tamagawa ◽  
Norikazu Ishimatsu
Keyword(s):  
Shock Wave ◽  
Growth Rate ◽  
Endothelial Cells ◽  
Shock Waves ◽  
Shock Tube ◽  
Shape Index ◽  
Plane Shock ◽  
Underwater Shock Wave ◽  
Extracorporeal Shock Wave

This paper describes effects of shock waves on cells to certificate the angiogenesis by shock wave (pressure wave) in the clinical application such as ESW (Extracorporeal Shock Wave). Especially, to investigate the effects of shock waves on the endothelial cells in vitro, the cells worked by plane shock waves using shock tube apparatus are observed by microscope. The peak pressure working on the endothelial cells at the test case is 0.4 MPa. After working shock waves on suspended cells, the disintegration, shape and growth rate (area per one cell and population of cells) are measured by image processing. It is found that the younger generation cells have small differences of shape index, and the growth rate of the shock-worked cells from 0 to 4h are clearly high compared with control ones. It is concluded that once shock waves worked, some of them are disintegrated, but the other has capacity to increase growth rate of cell culture in vitro. This preliminary result will be applied to fundamental investigations about shock wave stimulus on several kinds of cells in future.

scholarly journals The air pressure on a cone moving at high speeds.—I

1933 ◽  
Vol 139 (838) ◽  
pp. 278-297 ◽  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Wave Front ◽  
Abrupt Change ◽  
The Body ◽  
Plane Shock Wave ◽  
Plane Shock ◽  
High Speeds ◽  
Air Stream ◽  
Continuous Field

When a body moves through air at a uniform speed greater than that of sound, a shock wave is formed which remains fixed relative to the body. This wave is situated on a surface where a very abrupt change in density and velocity occurs. It can be seen as a sharp line in photographs of bullets in flight. In front of this surface the air is stationary, behind it there is a continuous field of fluid flow which may contain further shock waves. The nature of these shock waves is well known and the equations which govern their propagation were first obtained by Rankine. The work of Rankine, however, seems to have escaped the notice of subsequent writers and it was not till some years later that they were rediscovered by Hugoniot to whom they are usually attributed. Rankine’s equations give the relationship between the conditions in front and behind a plane shock wave. They connect the ratio of the density in front and behind the wave with the components of velocity normal to the wave. They have been applied by Meyer to find the flow in the neighbourhood of an inclined plane or wedge moving at high speeds. Meyer begins with a plane shock wave reduced to rest by giving the whole field a suitable velocity perpendicular to its plane. He then gives the whole field a velocity parallel to the wave front. The system is then a steady one, the shock wave remaining at rest, but the direction of motion of the air, which is now oblique to the wave, suffers an abrupt change at the wave front. By combining two such shock waves intersecting at a point, but not continuing beyond the intersection, a system can be devised in which all the air on one side of the pair of waves is moving with a uniform velocity. The air which passes through one wave is deflected, say, upwards, while that which passes through the other is deflected downwards. This system can evidently be bounded by a solid wedge, the faces of which are parallel to the two parts of the deflected air stream.

scholarly journals Effect of wavy wall strut fuel injector on shock wave development and mixing enhancement of fuel and air for a scramjet combustor

2020 ◽  
Author(s):  
Obula Reddy Kummitha ◽  
K M Pandey
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Shock Waves ◽  
Shear Layer ◽  
Wave Generation ◽  
Wavy Wall ◽  
Fuel Injector ◽  
Shock Wave Generation ◽  
Shear Mixing ◽  
Wave Development

Abstract The shear mixing and streamline vortices are the notable parameters to influence the air–fuel mixing in hypersonic flows. The shock wave development and Mach number significantly influence the shear mixing phenomenon. Hence, this research introduced an unconventional strut and tested its performance for the generation of shock waves at different flow conditions (M = 2,4,6). The Reynolds-averaged Navier–Stokes equations are solved to evaluate the performance of the new strut. Both the DLR scramjet strut injector and wavy wall strut injector are assessed for the shear mixing development. Turbulence for the association of shock waves, mixing layer, and the boundary layer has been modeled with the SST k-ω model. The variation in shock development and its interactions are investigated further with an increase in Mach number. The scramjet flow structure differentiation found the increased number of oblique shock waves with the wavy wall strut fuel injector. It increases the turbulence level with increased streamline vortices, turbulent intensity, and turbulent kinetic energy. The shock wave generation analysis at different Mach numbers (M = 2,4,6) found fewer interactions between the shock wave and shear layer with increased Mach number. From the examination of shock wave generation and its interaction with the shear layer and analysis of turbulent parameters, it is found that the wavy wall strut has an appreciable effect on shock-induced blend augmentation of fuel and air.

Spherically Symmetric Shock Waves in Materials with a Nonlinear Stress-Strain Dependence

2019 ◽  
Vol 945 ◽  
pp. 807-812
Author(s):  
Victoria E. Ragozina ◽  
Yulia E. Ivanova
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Dynamic Properties ◽  
Nonstationary Problem ◽  
Plane Shock ◽  
Spherically Symmetric ◽  
Stress Strain ◽  
Strain Dependence ◽  
Nonlinear Stress ◽  
Deformation Features

The paper considers the dynamic deformation features of constructional materials with nonlinear stress-strain dependence. For the one-dimensional shock waves with nonzero curvature arising in constructions under dynamic loading the propagation regularities are studied on the basis of the matched asymptotic expansions method. In the nonstationary problem with the longitudinal spherical shock wave the relations for simultaneous consideration of dynamic properties in the outer and inner problem of the perturbation method are obtained. The solution in the front-line area is constructed on the basis of the evolution equation different from ones for a plane longitudinal wave. The need for a solving of an additional ODE system for matching outer and inner expansions is shown. It is obtained that the outer solution asymptotics in the spherically symmetric problem contains waves reflected from the leading front in contrast to the solution behavior behind the front of the plane shock wave.

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