Experiments on flame propagation and detonation onset behind two solid obstructions were carried out in premixed stoichiometric hydrogen–oxygen mixtures at 20 kPa in a closed-ended tube. Obstacles with three different blockage ratios (25%, 40%, and 80%) were used, and the arrangement between the obstacles was changed in terms of blockage distribution (increasing, decreasing, and equivalent); obstacle

Kinetics of physicochemical processes occurring during combustion of a hydrogen–air mixture initiated by a shock wave was studied using state-to-state and mode models that take into account nonequilibrium vibrational excitation of N2, O2, H2, and OH molecules. The effect of vibrational–translational relaxation on the induction time was considered: it was shown that the delay in establishing thermodynamic

When a high explosive detonates, a large amount of energy is released within a short time, creating a high-temperature and high-pressure environment accompanied by a blast wave. When the blast wave interacts with field obstacles such as building structures and ground soil, it produces a reflected wave. The complexity of the pressure field created by blast waves depends on the spatial characteristics

In this study, experiments were carried out to investigate the detonation velocity behavior near limits in rough-walled tubes. The wall roughness was introduced by using different spiral inserts in 76.2-mm-diameter, 50.8-mm-diameter, 38.1-mm-diameter, and 25.4-mm-diameter tubes. Different pre-mixed mixtures, CH4 + 2O2, C2H2 + 2.5O2, C2H2 + 2.5O2 + 70%Ar, and 2H2 + O2 were tested in the experiments

The effects of ozone \(({\hbox {O}}_{3})\) or nitrogen dioxide \(({\hbox {NO}}_{2})\) as oxygen atom precursors on the characteristic length-scales of low-temperature chemistry (LTC)-affected detonation propagating in dimethyl \({\hbox {ether}}{-}{\hbox {O}}_{2}{-}{\hbox {CO}}_{2}\) mixtures were investigated using the Zeldovich–von Neumann–Döring model. The effect of these two additives on the energy

Diaphragm opening processes with a finite time affect the generated shock waves and shock tube flows. This effect is dominant in short and low-pressure shock tubes. In this research, a high-speed visualization of the opening process of a cellophane diaphragm, which is a suitable material for operation in a low-pressure shock tube, is conducted. The self-shaping opening morphology of cellophane diaphragms

Classical Navier–Stokes equations fail to predict shock wave profiles accurately. In this paper, the Navier–Stokes system is fully transformed using a velocity variable transformation. The transformed equations termed the recast Navier–Stokes equations display physics not initially included in the classical form of the equations. We then analyze the stationary shock structure problem in a monatomic

The TNT equivalences of equal masses of propane, a stoichiometric mixture of propane and oxygen, and ammonium-nitrate–fuel-oil (ANFO) were calculated based on the peak hydrostatic and dynamic pressures, the hydrostatic and dynamic pressure positive-phase impulses, and the positive-phase integrated work flux. It was assumed that the propane had been dispersed as a vapour/droplet cloud to form a stoichiometric

New data on the temperature of water shock-compressed to 79 GPa are presented. Thermal radiation from a water layer compressed by incident shock waves and shock waves reflected from a lithium fluoride or sapphire window was recorded in the range of incident-wave intensity of 28–36 GPa. The reflected-wave pressures were in the range of 49–79 GPa. The temperature measured at the pressure of 79 GPa was

Morphology and dynamics at the mesoscale play crucial roles in the overall macro- or system-scale flow of heterogeneous materials. In a multi-scale framework, closure models upscale unresolved sub-grid (mesoscale) physics and therefore encapsulate structure–property (S–P) linkages to predict performance at the macroscale. This work establishes a route to S–P linkage, proceeding all the way from imaged

Traditionally, Pitot rake test models have been used to take time- and spatially resolved impact pressure measurements in impulse facilities for flow characterisation. When expansion tubes are used for the study of hypervelocity planetary entry phenomena, generally the post-shock flow in the test section strongly radiates. This paper outlines a simple method which uses a high-speed camera in addition

It is well established that the knowledge about shock wave propagation in the free field cannot be applied to confined environments, especially when it comes to predicting the reflected shock wave. With the increase in accidental or intentional detonations of explosives in confined or urban environments, it is important to study and thoroughly understand the propagation of shock waves to provide behavior

The paper by J.M. Dewey (Shock Waves 29(4):583–587, 2019) described the development of an Excel-based interface that provides the physical properties of blast waves generated by propane/oxygen explosions. The interface was developed using the data from a nominal 20 ton explosion of an assumed stoichiometric propane/oxygen mixture. Comparisons of data from the interface with measurements of small-scale

The problem of combustion stabilization in a duct with supersonic flow at the entrance is studied by means of numerical simulation, with the use of experimental data if available. The influence of the transient process of combustion development on the final flow structure is demonstrated. Four examples are considered and analyzed: oscillations of a pseudoshock with combustion in an asymmetric duct

A water transportation engine of a new type—a pulsed detonation hydroramjet (PDH)—has been designed, manufactured, and tested. The PDH is a pulsed detonation tube (DT) inserted in an open-ended water guide. The thrust is developed by shock-induced pulsed water jets periodically emanating from the water guide nozzle. Numerical simulations indicate that valveless and valved PDH models can produce thrust

The aim of this work was to study the dynamics of deflagration-to-detonation transition (DDT) following flame acceleration in a cylindrical tube. We combined high-speed video recordings of self-luminescence and traditional local flow measurements to study the DDT process in a stoichiometric acetylene–oxygen mixture with argon dilution and nitrogen dilution. Experiments were carried out in a cylindrical

The transition between different combustion regimes is investigated experimentally for a stoichiometric argon-diluted n-decane/O2 mixture. The focus is put on the influence of initial temperature (T = 420–470 K) and pressure (P = 1.5–3 bar) on the regime transitions. Fast schlieren visualization (≥ 120 kHz) and high-speed pressure and temperature measurements are used to monitor the evolution of the

A well-posed mathematical model of nonisothermal, two-phase, two-velocity flow of a bubbly medium with chemically inert liquid and chemically inert or active gas bubbles is proposed. The model is based on the two-phase Euler equations with the introduction of an additional pressure at the gas-bubble surface, which ensures the well-posedness of the Cauchy problem for a system of governing equations

Regimes of continuous spin detonation and continuous multifront detonation in a hydrogen–oxygen mixture are obtained in a plane-radial combustor with an inner diameter of 100 mm and exhaustion toward the periphery. The fuel-lean limits of detonation in terms of the specific flow rate of the mixture are determined. For continuous spin detonation, transverse detonation waves and the flow in their vicinity

Cellular detonation flows in bi-disperse oxygen suspensions of micron-, submicron-, and nano-sized aluminum particles are studied numerically on the basis of the semiempirical model of detonation. The transition from diffusion-limited combustion of micron-sized particles to the kinetic combustion regime of nano-sized aluminum particles is taken into account. The influence of the particle size and the

The Hydrogen Unconfined Combustion Test Apparatus (HUCTA) was designed and built to study the blast waves produced from unconfined hydrogen/oxygen deflagrations. The HUCTA uses evacuated balloons of up to 2 m in diameter which are filled with a combustible combination of gaseous hydrogen–oxygen mixtures. The well-mixed gases are ignited with an electric spark at the center of the sphere, resulting

We discuss the effect on the transient dynamics of the Richtmyer–Meshkov instability due to small-scale perturbations introduced by a set of solid circular cylinders located along the material interface. The arrangement of the cylinders mimics (in a two-dimensional domain) the presence of the solid supporting grid wires used in the formation of the material interface in an experimental setup. The numerical

We have investigated one-dimensional compression waves, produced by heat addition in quiescent and uniform initial conditions, in six different supercritical fluids, each taken in four states ranging from compressible pseudo-liquid fluid to ideal gas. Navier–Stokes simulations of a canonical semi-infinite domain flow problem, spanning five orders of magnitude of heating rate, are also carried out to

Shock waves are used to treat musculoskeletal injuries and trigger the body’s mechanisms to initiate healing; however, the cellular and molecular working mechanisms are not fully known. Raman spectroscopy may be a useful tool to provide information on structural changes. Solid collagen type I from rat tail (> 90% pure) was suspended in water and was exposed in vitro to different numbers of shock waves

To gather test data of the nonequilibrium flow in CO2 and investigate the influence of the two-temperature nonequilibrium model on numerical simulations, measurements of shock standoff distances over hypersonic spheres in CO2 have been taken in the hypervelocity ballistic ranges of the Hypervelocity Aerodynamics Institute, China Aerodynamics Research and Development Center. Corresponding numerical

Two-dimensional shock–bubble interaction is an analogy of the steady three-dimensional jet flow in a scramjet. On the basis of Navier–Stokes simulations, a cylindrical bubble embedded with hydrogen surrounded by air was accelerated by a shock. The evolution can be divided into the lobe-emergence stage, the back-lobe suction stage, and the equilibrium stage. Based on the inhomogeneity between the hydrogen

A new hypersonic Mach 12 nozzle has been designed and manufactured for a large-scale expansion tube. The nozzle design goals were to produce a Mach 12 flow, with a core flow diameter of at least 300 mm and a maximum exit flow angle non-uniformity of less than \({2}^{\circ }\). The nozzle has been designed by coupling a RANS CFD solver with a parallel simplex algorithm to solve the computationally expensive

Projectile accelerations above \(500~\hbox {ms}^{-2}\) are commonly encountered in aerodynamic applications, but suitable validation data are rare in this regime. Experimental transonic velocity range data for a sphere decelerating under its own drag have been used to validate a numerical model for decelerating objects. The validated model is then used to explore the flow field ahead of objects decelerating

In this study, free-flight tests of a sphere for Reynolds numbers between 3.9 × 103 and 3.8 × 105 and free-flight Mach numbers between 0.9 and 1.6 were conducted using a ballistic range, and compressible low-Reynolds-number flows over an isolated sphere were investigated with the schlieren technique. The flow visualization was carried out under low-pressure conditions with a small sphere (minimum diameter

Experiments have been conducted in a supersonic rectangular duct (Mach 1.4), with a normal shock wave/boundary layer interaction. The duct is designed in a modular fashion so that its aspect ratio can be varied without a change in the flow geometry. The shock location, duct height, and Mach number are kept constant, while varying the aspect ratio. Conventional and inclined schlieren techniques have

The near-limit gaseous detonation behavior of three different methane–oxygen mixtures was investigated. Experiments were performed in transparent tubes of three different inner diameters (d). Due to the relatively large tube length l (\(\frac{l}{d} > 2500\) except \(\frac{l}{d} > 1000\) for the largest diameter), the tube was arranged in a spiral configuration for the convenience of testing. Photodiodes

Scaling parameters of shock-wave/turbulent boundary-layer interactions generated by a semi-infinite standing cylinder were explored in a combined numerical and experimental effort, consisting of Reynolds-averaged Navier–Stokes simulations and high-speed schlieren imaging. The primary interaction variable, the cylinder diameter (d), and a secondary interaction variable, the boundary-layer thickness

The shock response of a polymer-bonded copper powder was investigated by means of plate impact experiments in a gas gun (pressure range 1–8 GPa) and using in-contact explosive loading (pressures up to 37 GPa). Stress gauges were used to determine the material shock states in the planar impact, and the experimental data of shock and particle velocities (U, u) were fitted to a straight line giving a

The paper presents unique blast experiments in reference to scientific literature and official standards. Experimental scenarios reflect a hypothetical realistic combat situation of a human being covered from a blast wave behind a rigid building corner. In the scenario assumed, the overpressure loads affect the lungs while the person is standing or the eardrums while the person is kneeling at the aiming

A high-order, quasi-one-dimensional, reacting, compressible flow solver is developed to simulate non-ideal effects and chemical kinetics in shock tube systems. To this end, physical models for the thermoviscous boundary-layer development, area variation, gas interfaces, and reaction chemistry are considered. The model is first verified through simulations of steady isentropic nozzle flow, multi-species

Surrogate models for hotspot ignition and growth rates were presented in Part I (Nassar et al., Shock Waves 29(4):537–558, 2018), where the hotspots were formed by the collapse of single cylindrical voids. Such isolated cylindrical voids are idealizations of the void morphology in real meso-structures. This paper therefore investigates the effect of non-cylindrical void shapes and void–void interactions

Traumatic brain injury such as that developed as a consequence of blast is a complex injury with a broad range of symptoms and disabilities. Computational models of brain biomechanics hold promise for illuminating the mechanics of traumatic brain injury (TBI) and for developing preventive devices. However, reliable material parameters are needed for models to be predictive. Unfortunately, the properties

A series of six, large-scale tests were performed at the Eglin Air Force Base blastpad facility to serve as a validation benchmark for the explosive dispersal of particles. The series contained two baseline tests, one tungsten liner test, and three steel liner tests. Careful emphasis was placed on design of the experiments to allow ease of simulation, uncertainty quantification of experimental inputs