An experimental investigation of the stability of converging cylindrical shock waves in air

Takayama, K.; Kleine, H.; Grönig, Hans

doi:10.1007/bf00277710

Cited by 112 publications

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“…It was found that the similarity constant α was about 0.835 for a strong cylindrical converging shock wave in air (with adiabatic exponent γ = 1.4). Later, several experiments (Matsuo & Nakamura 1980, 1981Takayama et al 1987;Baronets 1994;Hosseini & Takayama 2010;Kjellander et al 2011) were performed to determine the value of α with different incident Mach numbers and various adiabatic exponents of gases. The results indicated that the value of α was heavily dependent on the adiabatic exponent and could remain stable in a wide range of incident shock Mach numbers.…”

Section: Features Of Cylindrical Shock Wavesmentioning

confidence: 99%

“…In laboratory conditions, a planar shock wave can be accurately formed in an ordinary shock tube, while a converging shock wave, especially with a controllable shape, is difficult to obtain because of its non-uniformity and variability in shape and strength. Previous experimental works on the RM instability mainly focused on the planar shock case (Brouillette 2002;Ranjan, Oakley & Bonazza 2011), with only a few exceptions (Hosseini & Takayama 2005;Luo et al 2014a;Si et al 2014b), although a great deal of effort has been taken to generate converging shock waves (Perry & Kantrowitz 1951;Takayama, Kleine & Gronig 1987;Apazidis & Lesser 1996;Hosseini, Onodera & Takayama 2000;Dimotakis & Samtaney 2006;Zhai et al 2010). It is known that the shock waves often maintain curved shapes in various applications (e.g.…”

mentioning

confidence: 99%

“…Cylindrical converging shock waves were generated for the first time by Perry & Kantrowitz (1951) using a horizontal annular shock tube, which consists of a cone-shaped inner core and an outer cylindrical shell. Later, a vertical annular coaxial shock tube was constructed by the group of Professor Takayama (Takayama et al 1987;Watanabe, Onodera & Takayama 1995;Hosseini et al 2000) and gradually modified to observe uniformly shaped toroidal shock waves (Hosseini & Takayama 2005. A different shock tube with a conically shaped test section was built to study converging shock waves by the group of Professor Apazidis (Apazidis & Lesser 1996;Apazidis et al 2002;Kjellander, Tillmark & Apazidis 2011).…”

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confidence: 99%

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Experimental investigation of cylindrical converging shock waves interacting with a polygonal heavy gas cylinder

Long

Zhai

et al. 2015

J. Fluid Mech.

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The interaction of cylindrical converging shock waves with a polygonal heavy gas cylinder is studied experimentally in a vertical annular diaphragmless shock tube. The reliability of the shock tube facility is verified in advance by capturing the cylindrical shock movements during the convergence and reflection processes using high-speed schlieren photography. Three types of air/SF 6 polygonal interfaces with cross-sections of an octagon, a square and an equilateral triangle are formed by the soap film technique. A high-speed laser sheet imaging method is employed to monitor the evolution of the three polygonal interfaces subjected to the converging shock waves. In the experiments, the Mach number of the incident cylindrical shock at its first contact with each interface is maintained to be 1.35 for all three cases. The results show that the evolution of the polygonal interfaces is heavily dependent on the initial conditions, such as the interface shapes and the shock features. A theoretical model for circulation initially deposited along the air/SF 6 polygonal interface is developed based on the theory of Samtaney & Zabusky (J. Fluid Mech., vol. 269, 1994, pp. 45-78). The circulation depositions along the initial interface result in the differences in flow features among the three polygonal interfaces, including the interface velocities and the perturbation growth rates. In comparison with planar shock cases, there are distinct phenomena caused by the convergence effects, including the variation of shock strength during imploding and exploding (geometric convergence), consecutive reshocks on the interface (compressibility), and special behaviours of the movement of the interface structures (phase inversion).

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Section: Features Of Cylindrical Shock Wavesmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Experimental investigation of cylindrical converging shock waves interacting with a polygonal heavy gas cylinder

Long

Zhai

et al. 2015

J. Fluid Mech.

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“…Although no theory and little analysis has been published on imploding toroidal waves [13], many studies have been done on cylindrical waves [14][15][16][17][18] due to the simplicity of the geometry. It is possible to imagine approximating the focal region of an imploding toroidal wave as an imploding cylindrical wave.…”

Section: Theory and Simulationsmentioning

confidence: 99%

“…In shock focusing, a collapsing shock or detonation wave generates a high-pressure and high-temperature focal region by adiabatically compressing shocked gas as it flows into an everdecreasing area [11][12][13][14][15][16][17][18]. This compression increases the postdetonation wave pressure higher than the Chapman-Jouguet (CJ) pressure, resulting in an increasingly overdriven detonation wave.…”

Section: Introduction Ementioning

confidence: 99%

Toroidal Imploding Detonation Wave Initiator for Pulse Detonation Engines

Jackson

Shepherd

2007

AIAA Journal

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Imploding toroidal detonation waves were used to initiate detonations in propane-air and ethylene-air mixtures inside of a tube. The imploding wave was generated by an initiator consisting of an array of channels filled with acetylene-oxygen gas and ignited with a single spark. The initiator was designed as a low-drag initiator tube for use with pulse detonation engines. To detonate hydrocarbon-air mixtures, the initiator was overfilled so that some acetylene oxygen spilled into the tube. The overfill amount required to detonate propane air was less than 2% of the volume of the 1-m-long, 76-mm-diam tube. The energy necessary to create an implosion strong enough to detonate propane-air mixtures was estimated to be 13% more than that used by a typical initiator tube, although the initiator was also estimated to use less oxygen. Images and pressure traces show a regular, repeatable imploding wave that generates focal pressures in excess of 6 times the Chapman-Jouguet pressure. A theoretical analysis of the imploding toroidal wave performed using Whitham's method was found to agree well with experimental data and showed that, unlike imploding cylindrical and spherical geometries, imploding toroids initially experience a period of diffraction before wave focusing occurs. A nonreacting numerical simulation was used to assist in the interpretation of the experimental data.

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Optical Flow Visualization

Kontis

Zare‐Behtash

2010

Encyclopedia of Aerospace Engineering

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Optical flow visualization techniques rely on the changes in flow density and hence the refractive index of the flow. Through various flow visualization techniques an image of the flow field is obtained which can be either qualitative, quantitative, or even both. The use of the appropriate visualization technique strongly depends on the flow field under investigation and the flow properties sought. The optical visualization techniques described here fall into the following categories: shadowgraphy, schlieren, moiré deflectometry, and interferometry. The optical tomography method which allows for the three‐dimensional reconstruction of the flow using two‐dimensional results is also briefly described.

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An experimental investigation of the stability of converging cylindrical shock waves in air

Cited by 112 publications

References 15 publications

Experimental investigation of cylindrical converging shock waves interacting with a polygonal heavy gas cylinder

Experimental investigation of cylindrical converging shock waves interacting with a polygonal heavy gas cylinder

Toroidal Imploding Detonation Wave Initiator for Pulse Detonation Engines

Optical Flow Visualization

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