Shock tunnels are important ground test facilities that can generate high-enthalpy flow. Flight velocity at a high Mach number can be simulated for aerodynamic testing of chemically reacting flows. However, the application of these tunnels is limited due to the only milliseconds-long test duration, especially for aerodynamic force measurement using traditional strain gauge balances. This study presents

In this paper, we propose a robust pseudo-arc-length moving-mesh method (PALM) which adopts the strategy of overall movement and block calculation for numerical simulation of detonation wave propagation in three dimensions. The pseudo-arc-length moving-mesh method involves governing equations’ evolution, mesh redistribution, and positivity-preserving analysis. Second-order finite-volume schemes and

This work presents a numerical study of detonation initiation by means of a focusing shock wave. The investigated geometry is a part of a pulsed detonation combustion chamber, consisting of a circular pipe in which the flow is obstructed by a single convergent–divergent axisymmetric nozzle. This obstacle acts as a focusing device for an incoming shock wave, serving as a low-energy detonation initiator

The blast wave generated by a high explosive detonation is dependent not only on the shape of the charge but on the location of the detonator or detonators. Even for a spherical charge, the blast wave can be very asymmetric if the initiation is not at the center of the charge. The asymmetry is even greater for cylindrical charges. High-resolution, high-fidelity calculations of the blast wave generated

In this paper, computations of gaseous detonations in several configurations are performed and discussed. The objective is to investigate the detonation characteristics, specially the influence of losses, through a quantitative analysis of the mean hydrodynamic structure. The results are divided into two parts: The first one relates to the propagation of ideal detonations without losses and to their

A new experimental method for evaluating the detonability of fuel–air mixtures (FAMs) based on measuring the deflagration-to-detonation (DDT) run-up distance and/or time in a standard pulse detonation tube (SDT) is used to rank gaseous premixed and non-premixed FAMs by their detonability under substantially identical thermodynamic and gasdynamic conditions. In the experiments, FAMs based on hydrogen

This paper develops a new empirical formula for the prediction of the triple point path in irregular shock reflection cases. Numerical simulations using a two-dimensional axisymmetric multi-material arbitrary Lagrangian–Eulerian formulation are employed to obtain the data of fluid density. Using the data of fluid density and nodal coordinates, the gradients of fluid density are determined and then

Rapid, accurate assessment of the yield of a large-scale urban explosion will assist in implementing emergency response plans, will facilitate better estimates of areas at risk of high damage and casualties, and will provide policy makers and the public with more accurate information about the event. On 4 August 2020, an explosion occurred in the Port of Beirut, Lebanon. Shortly afterwards, a number

The structure of planar shock waves propagating through argon, xenon, and krypton is calculated using the direct simulation Monte Carlo method for Mach numbers 2, 5, and 10. The upstream temperature considered in the present paper varies from 30 to 8000 K, depending on the gas species and Mach number. Both quantum and classical approaches to the intermolecular collisions based on ab initio potential

The work is dedicated to the experimental and numerical study of the mechanisms of gaseous detonation initiation in a stoichiometric hydrogen–oxygen mixture due to the reflection of a shock wave from a complex-shaped end wall. Several elliptic surfaces of different geometries, including distributed ones, were considered. We refer to such reflectors with multiple elliptical surfaces as multi-focusing

In this paper, blast mitigation using water mist was evaluated to assess the operational capability of the use of firefighting systems implemented in ships or infrastructures to reduce blast effects. In particular, we tried to determine the mitigation that could be obtained in specific situations. A tunnel equipped with a water mist system enabled us to assess the mitigation impact of water mist on

The direct numerical simulation of blast waves is a challenging task due to the wide range of spatial and temporal scales involved. Moreover, in a real environment (topography, urban area), the blast wave interacts with geometrical obstacles, resulting in reflection, diffraction, and wave recombination phenomena. The shape of the front becomes complex, which limits the efficiency of simple empirical

This study aims to investigate the effect of laser sheet orientation on the OH-planar laser-induced fluorescence (OH-PLIF) imaging of a detonation wave and to identify the potential benefit of using a transverse laser orientation, compared to the conventional frontal orientation. In this study, we developed a new laser-induced fluorescence (LIF) model, based on a preexisting one, to include a more

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 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

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

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

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

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

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 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 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

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

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

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

A hybrid wing body (HWB) concept is being considered by NASA as a potential subsonic transport aircraft that meets aerodynamic, fuel, emission, and noise goals in the time frame beyond 2035. While the concept promises advantages over a conventional wing-and-tube aircraft, it poses unknowns and risks, thus requiring in-depth and broad assessments. Specifically, the configuration entails a tight integration

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

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

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

A class of high-order nonlinear filter schemes by Yee et al. (J Comput Phys 150:199–238, 1999), Sjögreen and Yee (J Comput Phys 225:910–934, 2007), and Kotov et al. (Commun Comput Phys 19:273–300, 2016; J Comput Phys 307:189–202, 2016) is examined for long-time integrations of computational aeroacoustics (CAA) turbulence applications. This class of schemes was designed for an improved nonlinear stability

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

It is well known that hypersonic boundary-layer transition is sensitive to a surface roughness since the roughness may either trigger an early transition or delay the transition. Hypersonic transition is still poorly understood as there are a very limited number of studies in the literature. In the present work, we conduct a computational study on the transition process of a hypersonic Mach 6 flow

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

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

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

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

Although several mechanisms have been suggested as explanations for the low-frequency unsteadiness in shock wave/turbulent boundary layer interactions, questions remain on causes and effects. In this effort, we examine the observed asymmetry in large-scale shock motions to highlight which of the suggested mechanisms is most consistent with shock-speed observations and accompanying separation dynamics

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

Detonation velocity as a function of charge diameter is reported for Alliant Bullseye powder. Results are compared to those of mixtures of ammonium nitrate mixed with aluminum and ammonium nitrate mixed with fuel oil. Additionally, measurements of free surface velocity of flyers in contact with detonating Bullseye are presented and results are compared to those of hydrocode calculations using a Jones–Wilkins–Lee

Experimental investigations and numerical simulations of normal shock waves of different strengths propagating inside ducts with roughness are presented. The roughness is added in the form of grooves. Straight and branching ducts are considered in order to better explore the mechanisms causing attenuation of the shock and the physics behind the evolution of the complex wave patterns resulting from

A brief introduction of the time-filtered Navier–Stokes (TFNS) equations for very large eddy simulation (VLES) and its distinct features is presented. A set of nonlinear subscale models and their advantages over the linear subscale eddy viscosity models are described. A guideline for conducting a TFNS/VLES simulation is also provided. In this paper, we present simulations for three turbulent flows

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

A novel, adaptive discontinuity fitting technique has been further developed on unstructured dynamic grids to fit both shock waves and contact discontinuities in steady flows. Moreover, in order to efficiently obtain shock-fitting solutions, two strategies, direct-fitting and indirect-fitting, have been proposed to, respectively, deal with simple and complex flows. More specifically, without first

The HLLC (Harten–Lax–van Leer contact) approximate Riemann solver for computing solutions to hyperbolic systems by means of finite volume and discontinuous Galerkin methods is reviewed. HLLC was designed, as early as 1992, as an improvement to the classical HLL (Harten–Lax–van Leer) Riemann solver of Harten, Lax, and van Leer to solve systems with three or more characteristic fields, in order to avoid

Presented are results from a parametric investigation of wind-tunnel test-section configurations with a goal of stabilization of normal-shock-wave structure. The test section includes a two-flow-passage arrangement, where each passage is separated by a shock-wave-holding plate. The top wall for the top passage is contoured relative to the streamwise-flow direction, and a choking flap is located at

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