Experimental and numerical study of the interaction between a planar shock wave and a square cavity

1996 ◽  
Vol 313 ◽  
pp. 105-130 ◽  
Author(s):  
O. Igra ◽  
J. Falcovitz ◽  
H. Reichenbach ◽  
W. Heilig
Keyword(s):  
Shock Wave ◽  
Physical Model ◽  
Numerical Study ◽  
Wave Pattern ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Square Cavity ◽  
Planar Shock ◽  
Shock Wave Interactions ◽  
Planar Shock Wave

The interaction of a planar shock wave with a square cavity is studied experimentally and numerically. It is shown that such a complex, time-dependent, process can be modelled in a relatively simple manner. The proposed physical model is the Euler equations which are solved numerically, using the second-order-accurate high-resolution GRP scheme, resulting in very good agreement with experimentally obtained findings. Specifically, the wave pattern is numerically simulated throughout the entire interaction process. Excellent agreement is found between the experimentally obtained shadowgraphs and numerical simulations of the various flow discontinuities inside and around the cavity at all times. As could be expected, it is confirmed that the highest pressure acts on the cavity wall which experiences a head-on collision with the incident shock wave while the lowest pressures are encountered on the wall along which the incident shock wave diffracts. The proposed physical model and the numerical simulation used in the present work can be employed in solving shock wave interactions with other complex boundaries.

Experimental and Numerical Study of Shock Wave Interaction with Perforated Plates

2004 ◽  
Vol 126 (3) ◽  
pp. 399-409 ◽  
Author(s):  
A. Britan ◽  
A. V. Karpov ◽  
E. I. Vasilev ◽  
O. Igra ◽  
G. Ben-Dor ◽  
...  
Keyword(s):  
Shock Wave ◽  
Numerical Study ◽  
Wave Interaction ◽  
Wave Pattern ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Perforated Plates ◽  
Shock Reflections

The flow developed behind shock wave transmitted through a screen or a perforated plat is initially highly unsteady and nonuniform. It contains multiple shock reflections and interactions with vortices shed from the open spaces of the barrier. The present paper studies experimentally and theoretically/numerically the flow and wave pattern resulted from the interaction of an incident shock wave with a few different types of barriers, all having the same porosity but different geometries. It is shown that in all investigated cases the flow downstream of the barrier can be divided into two different zones. Due immediately behind the barrier, where the flow is highly unsteady and nonuniform in the other, placed further downstream from the barrier, the flow approaches a steady and uniform state. It is also shown that most of the attenuation experienced by the transmitted shock wave occurs in the zone where the flow is highly unsteady. When solving the flow developed behind the shock wave transmitted through the barrier while ignoring energy losses (i.e., assuming the fluid to be a perfect fluid and therefore employing the Euler equation instead of the Navier-Stokes equation) leads to non-physical results in the unsteady flow zone.

Planar Shock Focusing Through Perfect Gas Lens: First Experimental Demonstration

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Laurent Biamino ◽  
Christian Mariani ◽  
Georges Jourdan ◽  
Lazhar Houas ◽  
Marc Vandenboomgaerde ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Tube ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Shock Acceleration ◽  
Perfect Gas ◽  
Shock Focusing ◽  
Planar Case ◽  
Planar Shock ◽  
Planar Shock Wave

When a shock wave crosses an interface between two materials, this interface becomes unstable and the Richtmyer–Meshkov instability develops. Such instability has been extensively studied in the planar case, and numerous results were presented during the previous workshops. But the Richtmyer–Meshkov (Richtmyer, 1960, “Taylor Instability in Shock Acceleration of Compressible Fluids,” Commun. Pure Appl. Math., 13(2), pp. 297–319; Meshkov, 1969, “Interface of Two Gases Accelerated by a Shock Wave,” Fluid Dyn., 4(5), pp. 101–104) instability also occurs in a spherical case where the convergence effects must be taken into account. As far as we know, no conventional (straight section) shock tube facility has been used to experimentally study the Richtmyer–Meshkov instability in spherical geometry. The idea originally proposed by Dimotakis and Samtaney (2006, “Planar Shock Cylindrical Focusing by a Perfect-Gas Lens,” Phys. Fluid., 18(3), pp. 031705–031708) and later generalized by Vandenboomgaerde and Aymard (2011, “Analytical Theory for Planar Shock Focusing Through Perfect Gas Lens and Shock Tube Experiment Designs,” Phys. Fluid., 23(1), pp. 016101–016113) was to retain the flexibility of a conventional shock tube to convert a planar shock wave into a cylindrical one through a perfect gas lens. This can be done when a planar shock wave passes through a shaped interface between two gases. By coupling the shape with the impedance mismatch at the interface, it is possible to generate a circular transmitted shock wave. In order to experimentally check the feasibility of this approach, we have implemented the gas lens technique on a conventional shock tube with the help of a convergent test section, an elliptic stereolithographed grid, and a nitrocellulose membrane. First experimental sequences of schlieren images have been obtained for an incident shock wave Mach number equal to 1.15 and an air/SF6-shaped interface. Experimental results indicate that the shock that moves in the converging part has a circular shape. Moreover, pressure histories that were recorded during the experiments show pressure increase behind the accelerating converging shock wave.

Experimental and theoretical study of shock wave propagation through double-bend ducts

2001 ◽  
Vol 437 ◽  
pp. 255-282 ◽  
Author(s):  
O. IGRA ◽  
X. WU ◽  
J. FALCOVITZ ◽  
T. MEGURO ◽  
K. TAKAYAMA ◽  
...  
Keyword(s):  
Shock Wave ◽  
Wave Attenuation ◽  
Wave Pattern ◽  
Complex Flow ◽  
Shock Wave Attenuation ◽  
Planar Shock ◽  
Wave Patterns ◽  
Planar Shock Wave ◽  
Flow Evolution ◽  
Interferometric Study

The complex flow and wave pattern following an initially planar shock wave transmitted through a double-bend duct is studied experimentally and theoretically/numerically. Several different double-bend duct geometries are investigated in order to assess their effects on the accompanying flow and shock wave attenuation while passing through these ducts. The effect of the duct wall roughness on the shock wave attenuation is also studied. The main flow diagnostic used in the experimental part is either an interferometric study or alternating shadow–schlieren diagnostics. The photos obtained provide a detailed description of the flow evolution inside the ducts investigated. Pressure measurements were also taken in some of the experiments. In the theoretical/numerical part the conservation equations for an inviscid, perfect gas were solved numerically. It is shown that the proposed physical model (Euler equations), which is solved by using the second-order-accurate, high-resolution GRP (generalized Riemann problem) scheme, can simulate such a complex, time-dependent process very accurately. Specifically, all wave patterns are numerically simulated throughout the entire interaction process. Excellent agreement is found between the numerical simulation and the experimental results. The efficiency of a double-bend duct in providing a shock wave attenuation is clearly demonstrated.

Numerical study of a planar shock interacting with a cylindrical water column embedded with an air cavity

2017 ◽  
Vol 825 ◽  
pp. 825-852 ◽  
Author(s):  
Gaoming Xiang ◽  
Bing Wang
Keyword(s):  
Shock Wave ◽  
Water Column ◽  
Numerical Study ◽  
Incident Shock ◽  
Weno Scheme ◽  
Geometrical Parameters ◽  
Wave Impact ◽  
Planar Shock ◽  
Mach Numbers ◽  
The Impact

This paper performs a numerical study on the interaction of a planar shock wave with a water column embedded with/without a cavity of different sizes at high Weber numbers. The conservative-type Euler and non-conservative scalar two-equations representing the transportation of two-phase properties consist of the diffusion interface capture models. The numerical fluxes are computed by the Godunov-type Harten-Lax–van Leer contact Riemann solver coupled with an incremental fifth-order weighted essentially non-oscillatory (WENO) scheme. A third-order total variation diminishing (TVD) Runge–Kutta scheme is used to advance the solution in time. The morphology and dynamical characteristics are analysed qualitatively and quantitatively to demonstrate the breakup mechanism of the water column and formation of transverse jets under different incident shock intensities and embedded-cavity sizes. The jet tip velocities are extracted by analysing the interface evolution. The liquid column is prone to aerodynamic breakup with the formation of micro-mist at later stages instead of liquid evaporation because of the weakly heating effects of the surrounding air. It is numerically confirmed that the liquid-phase pressure will drop below the saturated vapour pressure, and the low pressure can be sustained for a certain time because of the focusing of the expansion wave, which accounts for the cavitation inside the liquid water column. The geometrical parameters of the deformed water column are identified, showing that the centreline width decreases but the transverse height increases nonlinearly with time. The deformation rates are nonlinearly correlated under different Mach numbers. The first transverse jet is found for a water column with an embedded cavity, whereas the water hammer shock and second jet do not occur under the impact of low intensity incident shock waves. The $x$-velocity component recorded at the rear stagnation point can remain unchanged for a comparable time after a declined evolution, which indicates that the downstream wall of the shocked water ring somehow moves uniformly. It can be explained that the acceleration of the downstream wall is balanced by the trailing shedding vortex, and this effect is more evident under higher Mach numbers. The increased enstrophy, mainly generated at the interface, demonstrates the competition of the baroclinic effects of the shock wave impact over dilatation.

The influence of the downstream pressure on the shock wave reflection phenomenon in steady flows

1999 ◽  
Vol 386 ◽  
pp. 213-232 ◽  
Author(s):  
G. BEN-DOR ◽  
T. ELPERIN ◽  
H. LI ◽  
E. VASILIEV
Keyword(s):  
Shock Wave ◽  
Wave Reflection ◽  
Numerical Study ◽  
Mach Reflection ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Steady Flows ◽  
Shock Wave Reflection ◽  
Wave Angle ◽  
Good Agreement

The effect of the downstream pressure (defined here as the wake pressure behind the tail of the reflecting wedge) on shock wave reflection in steady flows is investigated both numerically and analytically. The dependence of the shock wave configurations on the downstream pressure is studied. In addition to the incident-shock-wave-angle-induced hysteresis, which was discovered a few years ago, a new downstream- pressure-induced hysteresis has been found to exist. The numerical study reveals that when the downstream pressure is sufficiently high, an inverse-Mach reflection wave configuration, which has so far been observed only in unsteady flows, can be also established in steady flows. Very good agreement between the analytical predictions and the numerical results is found.

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