A study on the focusing phenomenon of a weak shock wave

2003 ◽  
Vol 217 (11) ◽  
pp. 1209-1220 ◽  
Author(s):  
H-D Kim ◽  
Y-H Kweon ◽  
T Setoguchi ◽  
S Matsuo
Keyword(s):  
Shock Wave ◽  
Mach Number ◽  
Peak Pressure ◽  
Weak Shock ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Weak Shock Wave ◽  
Tvd Scheme ◽  
Local Pressure ◽  
Gas Dynamic

When a plane shock wave reflects from a concave wall or when a curved shock wave reflects from a straight wall, it is focused at a certain location, resulting in extremely high local pressure and temperature. This focusing is due to a non-linear phenomenon of a shock wave. This focusing phenomenon has been extensively applied in a variety of engineering and medical areas. In the current study, the focusing phenomenon of a weak shock wave over a reflector is numerically investigated using a computational fluid dynamics (CFD) method. The total variation diminishing (TVD) scheme is used to solve the unsteady, two-dimensional, compressible, Euler equations. The Mach number of the incident shock wave is changed in the range from 1.1 to 1.5. Several different types of reflectors are employed to investigate the effect of the reflector on the focusing phenomenon of the weak shock wave. The focusing characteristics of the shock wave are investigated in terms of peak pressure, gas dynamic and geometrical foci. The results obtained are compared with previous experiment results that are available. The results show that the peak pressure of shock wave focusing and its location strongly depend on the Mach number of the incident shock wave and the reflector geometry. The location of the gas dynamic focus is always shorter than that of the geometrical one. This tendency is more remarkable as the incident shock wave becomes stronger. The present computations predict the experimental results with a very good accuracy.

scholarly journals Evolution of artificial disturbances in a shear layer at M=1.43

2021 ◽  
Vol 2057 (1) ◽  
pp. 012085
Author(s):  
O I Vishnyakov ◽  
P A Polivanov ◽  
A A Sidorenko
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Mach Number ◽  
Barrier Discharge ◽  
Separation Zone ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Plate Model ◽  
Hot Wire ◽  
Dielectric Barrier

Abstract The evolution of artificial disturbances in a laminar boundary layer on a flat plate model in the presence of an incident shock wave is considered. The flow is supersonic with the freestream Mach number M = 1.43. The study is carried out by hot-wire anemometry. A dielectric barrier discharge is used to generate disturbances. Data on the distribution in space of the average and non-stationary components of the mass flow are obtained. Disturbances created by the discharge and their evolution along the separation zone are recorded.

scholarly journals Experimental Study of the Weak Shock Wave Action on the Boundary Layer of a Plate at the Mach Number 2.5

2019 ◽  
Vol 14 (2) ◽  
pp. 46-55 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
A. D. Kosinov ◽  
Yu. G. Yermolaev ◽  
N. V. Semionov
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Experimental Study ◽  
Mach Number ◽  
Side Wall ◽  
Leading Edge ◽  
Weak Shock ◽  
Supersonic Boundary Layer ◽  
Weak Shock Wave ◽  
Frequency Spectra

Experimental study of the effect of a weak shock wave from the protuberance of two-dimensional roughness installed on the side wall of the test section of the wind tunnel on the supersonic boundary layer of the blunted flat plate at the Mach number 2.5 was carried out. The measurements were performed by a constant temperature hot-wire anemometer in the region of stream wise vortices generated by the shock wave from the protuberance during interaction with the flow in the vicinity of the leading edge of the model. The spectral and statistical analyses of the measured disturbances in the boundary layer were carried out. The amplitude-frequency spectra of mass flow pulsations and statistical diagrams of the measured disturbances in the supersonic part of the boundary layer were obtained.

Experimental Investigation of the Weak Shock Wave Influence on the Boundary Layer of a Flat Blunt Plate at the Mach Number 2.5

2019 ◽  
Vol 54 (2) ◽  
pp. 257-263 ◽  
Author(s):  
Yu. G. Ermolaev ◽  
A. D. Kosinov ◽  
V. L. Kocharin ◽  
N. V. Semenov ◽  
A. A. Yatskikh
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Experimental Investigation ◽  
Mach Number ◽  
Weak Shock ◽  
Weak Shock Wave

Propagation of a High Explosive Air Shock Wave Through Different Parts of an Animal Body

1955 ◽  
Vol 184 (1) ◽  
pp. 119-126 ◽  
Author(s):  
Carl-Johan Clemedson ◽  
Hjalmar Pettersson
Keyword(s):  
Shock Wave ◽  
Peak Pressure ◽  
High Explosive ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Pressure Oscillations ◽  
Pressure Peak ◽  
Peak Shock ◽  
The Brain ◽  
Different Parts

Anesthetized rabbits were exposed to high explosive shock waves in a detonation chamber and in a blasting range. A barium titanate crystal pressure transducer inserted into the skull, right thorax cavity, upper part of abdomen and femoral musculature was used for the recording of the pressure pattern of the tissue transmitted blast wave. Relatively homogeneous tissues such as those of the brain, abdomen and thigh musculature were found to modify the incident shock wave only little and are not significantly affected by it. The thoracal structures, especially the lungs on the other hand, due to their elastic and damping properties, cause a marked distortion of the incident wave. Only the main pressure peaks but not the more rapid, smaller pressure oscillations of a complex, multi-peak shock wave are transmitted through the lung. Generally, the peak pressure is but little changed by the passage through a tissue or organ. An exception constitutes the thorax when exposed to a short-lasting pressure peak such as that obtained in the blasting range experiments. In this case the peak pressure was considerably reduced.

scholarly journals Adjoint-based optimisation of detonation initiation by a focusing shock wave

Shock Waves ◽  
2021 ◽  
Author(s):  
S. Bengoechea ◽  
J. Reiss ◽  
M. Lemke ◽  
J. Sesterhenn
Keyword(s):  
Shock Wave ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Detonation Initiation ◽  
Axisymmetric Nozzle ◽  
Exponential Factor ◽  
Pulsed Detonation Engine ◽  
Pulsed Detonation ◽  
Detonation Engine ◽  
Adjoint Approach

AbstractAn optimisation study of a shock-wave-focusing geometry is presented in this work. The configuration serves as a reliable and deterministic detonation initiator in a pulsed detonation engine. The combustion chamber consists of a circular pipe with one convergent–divergent axisymmetric nozzle, acting as a focusing device for an incoming shock wave. Geometrical changes are proposed to reduce the minimum shock wave strength necessary for a successful detonation initiation. For that purpose, the adjoint approach is applied. The sensitivity of the initiation to flow variations delivered by this method is used to reshape the obstacle’s form. The thermodynamics is described by a higher-order temperature-dependent polynomial, avoiding the large errors of the constant adiabatic exponent assumption. The chemical reaction of stoichiometric premixed hydrogen-air is modelled by means of a one-step kinetics with a variable pre-exponential factor. This factor is adapted to reproduce the induction time of a complex kinetics model. The optimisation results in a 5% decrease of the incident shock wave threshold for the successful detonation initiation.

Visualization of separation and reattachment in an incident shock-induced interaction

2021 ◽  
pp. 095441002098349
Author(s):  
Yun Jiao ◽  
Chengpeng Wang
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Shear Stress ◽  
Separation Bubble ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Bottom Wall ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Oil Flow

An experimental study is conducted on the qualitative visualization of the flow field in separation and reattachment flows induced by an incident shock interaction by several techniques including shear-sensitive liquid crystal coating (SSLCC), oil flow, schlieren, and numerical simulation. The incident shock wave is generated by a wedge in a Mach 2.7 duct flow, where the strength of the interaction is varied from weak to moderate by changing the angle of attack α of the wedge from 8° and 10° to 12°. The stagnation pressure upstream was set to approximately 607.9 kPa. The SSLCC technique was used to visualize the surface flow characteristics and analyze the surface shear stress fields induced by the initial incident shock wave over the bottom wall and sidewall experimentally which resolution is 3500 × 200 pixels, and the numerical simulation was also performed as the supplement for a clearer understanding to the flow field. As a result, surface shear stress over the bottom wall was visualized qualitatively by SSLCC images, and flow features such as separation/reattachment and the variations of position/size of separation bubble with wedge angle were successfully distinguished. Furthermore, analysis of shear stress trend over the bottom wall by a hue value curve indicated that the relative magnitude of shear stress increased significantly downstream of the separation bubble compared with that upstream. The variation trend of shear stress was consistent with the numerical simulation results, and the error of separation position was less than 2 mm. Finally, the three-dimensional schematic of incident shock-induced interaction has been achieved by qualitative summary by multiple techniques, including SSLCC, oil flow, schlieren, and numerical simulation.

Evolution of weak shock wave in two-dimensional steady supersonic flow in dusty gas

2019 ◽  
Vol 160 ◽  
pp. 552-557 ◽  
Author(s):  
Rahul Kumar Chaturvedi ◽  
Pooja Gupta ◽  
L.P. Singh
Keyword(s):  
Shock Wave ◽  
Supersonic Flow ◽  
Weak Shock ◽  
Weak Shock Wave ◽  
Dusty Gas ◽  
Two Dimensional
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