The reflection of a converging cylindrical shock over a double curved wedge was investigated experimentally and numerically. The double curved wedge was specially designed to ensure that the wedge angle only changes at the corner during the cylindrical shock reflection. Seven different reflection processes existing in the planar case were reproduced in the converging case. The sudden variation of the

Primary blast wave impact on military personnel is of major concern, particularly as it relates to traumatic brain injury. To gain insights into the brain’s response to primary blast impact, the current research employed a surrogate head form filled with biogel brain simulant and subjected it to primary blast waves propagating 180 mm from a 1.7-g cyclotrimethylene trinitramine Class 5 (RDX) explosive

Experiments on shock–shock interactions were conducted in a transonic–supersonic wind tunnel with variable free-stream Mach number functionality. Transition between the regular interaction (RI) and the Mach interaction (MI) was induced by variation of the free-steam Mach number for a fixed interaction geometry, as opposed to most previous studies where the shock generator angles are varied at constant

We conducted a series of numerical simulations to understand the effect of the initiation process of cylindrical high explosives on the blast-wave behavior and peak overpressure distribution. The first case involved the explosion of a cylindrical high explosive whose length-to-diameter ratio was equal to 2 and that was vertically placed above the ground surface. The initiation point was at the top

In this paper, the water-exit phenomenon has been studied experimentally and numerically. Based on the volume-of-fluid model and the Schnerr–Sauer cavitation model, the water-exit supercavitation around different shapes of cavitator projectiles is investigated using a dynamic mesh technology and three-dimensional six-degree-of-freedom method. The numerical results are compared with the experimental

A model for predicting shock strength in a shock tube with a partially opened diaphragm using discharge-coefficient theory is presented. The model results are compared to an empirical correlation provided in the literature and numerical simulations. The shock-tube pressure ratio, the driver-gas type, and the Reynolds number are varied in the model and simulations. Simulations are analyzed to assess

The operation of free-piston-driven reflected shock tunnels has largely observed the rule of thumb that the nozzle throat diameter should not exceed one third the shock-tube diameter. This is intended to ensure drainage does not prematurely terminate the test time before wave effects. For successful testing at lower Mach numbers, a higher nozzle throat-to-exit area ratio is required, either resulting

In this study, the detonation diffraction and re-initiation processes around a single cuboid were studied experimentally. Experiments were performed in a 6-m-long duct with a cross section of 112 mm × 112 mm filled with stoichiometric methane–oxygen mixtures at initial pressures between 10 and 30 kPa. A cuboid was placed in the duct to form two perpendicular passages between the cuboid and the walls

The evolution of a particle cloud following its interactions with a blast wave and contact interface resulting from a detonating high-energy explosive is a difficult problem for both numerical simulations and physical experiments. In experiments, it is challenging to accurately characterize both the initial states of the explosive and the surrounding particle bed. There are also limitations in the

In expansion tube and shock tunnel facilities, freestream properties are generally inferred from the measurement of shock speeds using wall-mounted instrumentation. By measuring the shock arrival time at known locations along the facility wall, their spacing can be used to calculate the shock speed. These shock arrival measurements are generally taken using high-frequency pressure transducers. For

The effect of employing four different reactor models, Zeldovich–von Neumann–Döring (ZND), constant volume (CV), constant pressure (CP), and the Shock routine from Chemkin, to perform detonation-relevant chemical modeling was assessed. The simulation results were compared in terms of characteristic length scales and chemical analyses with four representative mixtures: \(\hbox {H}_{2}{-}\hbox {O}_{2}{-}\hbox

Spherical weak blast propagation above a rough periodic surface is investigated by performing numerical simulations of the Euler equations. The study of the reflection pattern shows that waves diffracted by the surface asperities merge to form an effective reflected shock. It is initially detached from the incident shock but gradually catches up with it. If the source energy is sufficient, the reflected

In response to the comment by M.I. Radulescu, the results in the original article publication are corrected and the degree of discrepancy is assessed to re-evaluate the accuracy of the semi-empirical model for predicting the trajectory of the transverse detonation during the re-initiation process of a diffracted cellular detonation wave from a channel. Despite a certain loss of accuracy, the conclusion

Literature regarding hypersonic shock/boundary-layer interaction is mostly restricted to calorically perfect gases, even though this condition is far from reality when temperature rises. High-temperature effects alter physical and transport properties of the fluid, due to vibrational excitation and gas dissociation, and chemical reactions must be considered in order to compute the flow field. In this

An incorrect model exponent derived from Whitham’s characteristic rule was used by Yuan et al. (Shock Waves 30:13–27, 2020) to predict the dynamics of detonation diffraction and re-initiation. In this comment, the correct value is presented and the impact of this error is evaluated.

Flame propagation experiments in stoichiometric H\(_2\)–air are conducted in a smooth 482-mm-long, 10-mm \(\times \) 10-mm square-cross-section channel, closed at the ignition end and open at the opposite end. Direct observation is used to track the flame acceleration dynamics. The effect of facility specific parameters (i.e., ignition energy, boundary conditions near the ignition end, window material

Rotating detonation engines (RDEs) have been observed to exhibit several operating modes and instabilities under different operation conditions (reactant mixture, injection pressure, engine geometry, injection mass flow rate, etc.). We develop the simplest model possible describing the operation of an RDE. This model takes into account the dependence of detonation properties on engine conditions, the

Research on the application of liquid fuels to continuously rotating detonation was conducted. A new method of mixture preparation was proposed. A special system of liquid fuel injection was designed and tested which is based on injecting into the detonation chamber a preheated liquid fuel partially mixed with hot air at conditions higher than the rich flammability limit. The specially selected conditions

This paper examines blast mitigation based on geometric means, namely a perforated plate or a chain mail, with or without a water film cover. This method may be used for the protection of structures, and its effectiveness and limitations were assessed. First, a shock tube was used to visualize the interaction of a blast wave profile with a metallic grid or with a metallic grid covered by a layer of

Nitrogen is proposed as a suitable driver gas candidate for the operation of free-piston-driven shock tunnels at low total enthalpies. When compressed adiabatically, nitrogen has a lower speed of sound than the commonly used driver gases, e.g., argon and helium, thus providing the ability to achieve tailored conditions and longer test durations at lower enthalpies. This paper describes the methodology

A new scaling is developed for both air and underwater blast waves based on dimensional analysis. The new length, time, velocity, and pressure scales are based on three control parameters: the energy release of the explosive \(E_{_\mathrm {HE}}\), the density of the undisturbed ambient medium \(\rho _{_0}\), and the speed of sound in the undisturbed ambient medium \(C_{_0}\). The shock wave propagation

The present study aims at providing insights into shock wave interference patterns in gas flows when a mixture different than air is considered. High-energy non-equilibrium flows of air and \(\hbox {CO}_2\)–\(\hbox {N}_2\) over a double-wedge geometry are studied numerically. The impact of freestream temperature on the non-equilibrium shock interaction patterns is investigated by simulating two different

Experiments are carried out to determine the effects of particle size and mass loading on the free-field blast wave from spherical, constant volume metalized explosive charges. The charges are comprised of gelled nitromethane with uniformly embedded aluminum, magnesium, or glass particles. Particle sizes are varied over an order of magnitude with particle mass fractions up to 50%. Peak blast overpressures

Current methods for testing blast pressures produced by fireworks are ad hoc and differ substantially from established methods for assessing injury risks from explosives. In this experimental study, pressure-versus-time waveforms were measured as a function of distance from the source for four consumer firecrackers and one consumer bottle rocket. Pressure-versus-time data were collected at 10 MHz using

The flow of high-speed air in ducts may result in the occurrence of multiple shock-wave/boundary-layer interactions. Understanding the consequences of such interactions, which may include distortion of the velocity field, enhanced turbulence production, and flow separation, is of great importance in understanding the operating limits and performance of a number of systems, for example, the high-speed

Wave rotors are unsteady flow machines that exchange energy through pressure waves. This has the potential for enhancing efficiency over a wide spectrum of applications, ranging from gas turbine topping cycles to pressure-gain combustors. This paper introduces an aerodynamic shape optimisation of a power generating non-axial micro-wave rotor turbine and seeks to enhance the shaft power output while

In this study, the characteristics of side-projected planar shock waves propagating through grid turbulence were investigated using a counter-driver shock tube. At the location of visualization of the shock–turbulence interactions, the range of the shock Mach numbers was \(M_{\mathrm {s}} = 1.01{-}1.15\) and the representative values of the turbulent Mach numbers \(\widetilde{M_{\mathrm {t}}}\) were

Angled and tapered injectors have been subjected to detonation fronts at high-pressure conditions and analyzed using high-speed videos. A total of 846 tests were conducted to characterize refill times and back-flow distances of nine different injector geometries. Water was used as the working fluid, and ethylene–oxygen was utilized to produce the detonation wave. Experiments were performed at two different

The blast waves from a series of explosions of stoichiometric, rich, and lean propane/oxygen mixtures have been analysed. The explosive mixtures were contained in hemispherical soap bubbles, 0.05 m in radius, with total masses in the order of 1 g. The blast waves were measured with a series of piezoelectric transducers, flush mounted in the horizontal surface supporting the charges, at various distances

This paper explores the ability of the Kurganov, Noelle, and Petrova numerical scheme included in the rhoCentralFoam solver of the OpenFOAM™software to model strong explosion processes, using typical gas dynamics concepts. The main objective of this study was to obtain a numerical tool to simulate strong explosions. Once the generated blast waves and their propagation were simulated, the numerical

A computational study has been carried out to assess the effectiveness of a porous medium as a passive control device suitable for reducing the drag in a normal-shock-wave/boundary-layer interaction at transonic speeds with a view toward application in aircraft wings. Reduction in overall drag is achieved via recirculation inside the porous medium, which primarily weakens the shock structure and hence

The diffraction of a shock wave over a stationary body is a problem of interest associated with the starting of shock tubes and expansion tubes which are well suited to studies of hypersonic flows. However, these facilities are characterized by very short test times. The transient parameters during the establishment of the detached bow shock in such impulsive facilities are important for both data

A computer modeling study is reported about the constant-piston-velocity compaction response of a 50% porous fine particle and air mixture. It is established that for the 10-\(\upmu \hbox {m}\) average particle diameter powder chosen (sugar), over the piston velocity range 100–1000 \(\hbox {m}\,\hbox {s}^{-1}\), a self-similar shock is formed in 12–14 particle diameters of motion (\({\approx }\,140~\upmu

An 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

For rotating detonation engines, the high-pressure region behind the detonation causes backflow into the plenum, making it difficult to properly design injectors to achieve the target pressure balance due to blockage of a part of the injector area during engine operation. In this paper, we present the pressure and thrust measurement of a rotating detonation engine with two different triplet injectors

In this paper, a series of experiments were performed to study the energy output characteristics of CL-20-based aluminized explosives in an explosion vessel. The influences of different aluminum mass contents on the shock wave pressure and the explosion power were systematically investigated. The results showed that the peak overpressure and the positive impulse of the initial shock wave decreased

A thermogravimetric study of oxidation of sulfide ore powders subjected to slow quasi-steady heating from 20 to 1000 °C is performed. Experiments on rapid shock wave and explosive heating of air suspensions of ore powders are carried out for modeling conditions of ore extraction in mines. Propagation of incident and reflected shock waves in air suspensions of fine-grained sulfide ores with particle

We solve the Euler equations to compute the interaction of a Mach 1.22 shock wave with a helium bubble contaminated by 28% air by mass. A ninth-order upwind scheme is used to calculate the left and the right states of the primitive variables as required by the AUSMD algorithm. The low numerical dissipation of the AUSMD algorithm makes it an ideal choice for computing long-time behavior of the bubble

Detonation propagation, re-initiation, and flame propagation in acetylene–air mixtures were investigated in a channel with a transverse dimension that is comparable with the width of the detonation cell. Experiments were carried out in a channel with a square cross-section of 5 mm \(\times \) 5 mm. The detonation wave passed from the driver section into the transparent test section. The trajectories

Understanding the physical mechanisms by which blast waves interact with their surroundings is paramount to protecting the safety of armed service personnel and equipment. This study evaluates and discusses modern technology used in blast pressure measurement as it relates to primary blast injuries such as traumatic brain injury. Factors influencing primary blast injury were established as peak overpressure

An experimental investigation was conducted to compare the blast mitigation performances of water layers, whose mass ratios to an explosive were \( m_{{\text{W}}} /m_{{\text{E}}} = 12.2,44.5,\;{\text{and}}\;107.2 \), with water droplets surrounding the explosive. The blast waveforms were measured using pressure transducers, and the motion of the water layer was recorded using a high-speed camera. When

Changing the flow rate of reactants being injected into a rotating detonation combustor (RDC) results in interesting behavior of the system. Prior studies have found that an increase in mass flow rate gradually increases the detonation wave speed before splitting the wave into multiple fronts. The focus of this study is in understanding the physics of such behavior through a combination of experiments

Experimental studies are performed for the near- and far-field characteristics of a plug nozzle jet with the objective to see the effect of truncation of the plug on mean flow characteristics of the jet and its control using vortex generators (VGs). To this end, the plug is truncated at 50%, 40%, and 30% of the axial length from the throat, and mean flow characteristics are studied by the schlieren

On 4 August 2020, an estimated 2.75 kt of ammonium nitrate exploded in the Port of Beirut, Lebanon. Rigby et al. (Shock Waves 30:671–675, 2020) used observations from numerous video recordings of the explosion to estimate the time-of-arrival of the primary shock at 38 positions, the distances of which from the centre of the explosion were determined from Google maps. These data were analysed to make

Deflagration-to-detonation transition (DDT) in a macroscale tube is investigated experimentally for stoichiometric ethylene–oxygen with O3 (ozone) addition. The effect of O3 addition on the DDT process is studied, including its dependence on initial pressure. This kinetic effect of ozone addition was investigated by examining the influence of ozone self-decomposition and ethylene ozonolysis on ignition

Experimental determination of test gas caloric quantities in high-enthalpy ground testing is impeded by excessive pressure and temperature levels as well as minimum test timescales of short-duration facilities. Yet, accurate knowledge of test gas conditions and stagnation enthalpy prior to nozzle expansion is crucial for a valid comparison of experimental data with numerical results. To contribute

We consider a three-dimensional unsteady flow with one, two, or four rotating detonation waves arising in an annular gap of an axially symmetric device between two parallel planes perpendicular to its symmetry axis. The corresponding problem is formulated and studied. It is assumed that there is a reservoir with quiescent homogeneous propane–air combustible mixture with given stagnation parameters;

Compressible mixtures in supersonic flows are subject to significant temperature changes via shock waves and expansions, which affect several properties of the flow. Besides the widely studied variable transport effects such as temperature-dependent viscosity and conductivity, vibrational and rotational molecular energy storage is also modified through the variation of the heat capacity $$c_p$$ c p

A series of experiments were performed to provide validation data for explosively driven multiphase flows at moderate-to-high volume fractions. A $$13 \times 6$$ 13 × 6 mm cylindrical packet of 115- $$\upmu $$ μ m steel particles was dispersed explosively. In contrast to shock tube studies, the particles were subjected to a high-Mach-number shock, in the presence of an ambient fluid, and a contact

Numerical simulations of two-dimensional inviscid detonations for a stoichiometric propane/oxygen gas mixture are performed using a detailed chemical reaction model. The UC San Diego model which includes 57 chemical species and 268 elementary reactions is mainly used in the present study. It is shown that a grid size of 3 µm can capture important features such as the unburned gas pocket behind the

This paper investigates the structure of normal shock waves for a planar steady flow of non-ideal dilute gases under variable viscosity and thermal conductivity using the Navier–Stokes–Fourier approach to the continuum model. The gas is assumed to follow the simplified van der Waals equation of state along with the power-law temperature-dependent coefficients of shear viscosity, bulk viscosity, and

A rotating detonation combustor (RDC) is a novel approach to achieving pressure gain combustion. Due to the steady propagation of the detonation wave around the perimeter of the annular combustion chamber, the RDC dynamic behavior is well suited to analysis with reduced-order techniques. For flow fields with such coherent aspects, the dynamic mode decomposition (DMD) has been shown to capture well

The effects of hydrogen peroxide ( $$\hbox {H}_{2}\hbox {O}_{2}$$ ) and tert-butyl hydroperoxide (TBHP), both hydroxyl radical precursors, on the characteristic length-scales of low-temperature-chemistry-affected (LTC-affected) detonation propagating in dimethyl-ether–oxygen–carbon-dioxide (DME– $$\hbox {O} _{2}$$ – $$\hbox {CO}_{2}$$ ) mixtures were investigated using the Zeldovich–von Neumann–Doring

One-dimensional, unsteady gaseous detonation propagation in a non-homogeneous medium is investigated numerically using the reactive, compressible Navier–Stokes equations with detailed chemistry. The effect of concentration inhomogeneity on the pulsating mode is modeled by a sinusoidal distribution of H2 mole fraction in a H2–O2 mixture. The mixture inhomogeneity, varied by changing the disturbance

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

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

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