Showing papers on "Shock (mechanics) published in 2020"
TL;DR: In this article, the impact of the angle between LSW and the deposited plane on tensile properties of both SLM-LSPed specimens was analyzed, and two kinds of LSW-induced atomic diffusion processes at the interfaces between both adjacent deposited layers were presented.
Abstract: High-performance integrated additive manufacturing with laser shock peening (LSP), is an innovative selective laser melting (SLM) method to improve mechanical properties, and refine microstructure in the surface layer of metallic components. Phase, residual stress distribution, surface micro-hardness, tensile properties and microstructural evolution of SLMed and SLM-LSPed specimens in horizontal and vertical directions were examined. In particular, typical microstructural features in the surface layer were characterized by transmission electron microscopy (TEM) observations. Results indicated that surface micro-hardness subjected to massive LSP treatment had significantly improved, tensile residual stress was transformed into compressive residual stress by LSP-induced plastic deformation, and both SLMed specimens in two directions exhibited a good combination of the ultimate tensile strength (UTS) and ductility. Meanwhile, high-density dislocations and a large number of mechanical twins were generated in the coarse α′ martensites by laser shock wave (LSW), and gradually evolved into refined α′ martensites. Furthermore, according to the included angle between LSW and the deposited plane, two kinds of LSW-induced atomic diffusion processes at the interfaces between both adjacent deposited layers were presented, and the influence mechanisms of the included angle between LSW and the deposited plane on tensile properties of both SLM-LSPed specimens were revealed. The hybrid additive manufacturing technology combined SLM with LSP realizes the high-efficiency and high-quality integrated manufacturing of the formed metallic components for practical applications.
182 citations
TL;DR: In this article, numerical simulations are applied to study the influence of the sinusoidal shock generator on the flow structure of the multi-hydrogen jet at supersonic crossflow.
86 citations
TL;DR: In this article, the authors investigated the effect of turbulence on the explosion process of a methane-air mixture under standard conditions, and the effect on explosion parameters, i.e., pmax, τe, and (dp/dt)max, was investigated by the turbulence produced by three different inert additives.
80 citations
TL;DR: In this article, the effect of massive laser shock peening (MLSP) on surface integrity of cast dumbbell shaped and cylindrical cast specimens of commercially pure titanium (CP-Ti) and to compare with those of untreated CP-Ti was investigated.
78 citations
TL;DR: In this article, a 3D full-sphere supernova simulation of non-rotating low-mass progenitors is presented, covering the entire evolution from core collapse through bounce and shock revival, through shock breakout from the stellar surface, until fallback is completed several days later.
Abstract: We present 3D full-sphere supernova simulations of non-rotating low-mass (∼9 M_⊙) progenitors, covering the entire evolution from core collapse through bounce and shock revival, through shock breakout from the stellar surface, until fallback is completed several days later. We obtain low-energy explosions (∼0.5–1.0 × 10⁵⁰ erg) of iron-core progenitors at the low-mass end of the core-collapse supernova (LMCCSN) domain and compare to a super-AGB (sAGB) progenitor with an oxygen–neon–magnesium core that collapses and explodes as electron-capture supernova (ECSN). The onset of the explosion in the LMCCSN models is modelled self-consistently using the VERTEX-PROMETHEUS code, whereas the ECSN explosion is modelled using parametric neutrino transport in the PROMETHEUS-HOTB code, choosing different explosion energies in the range of previous self-consistent models. The sAGB and LMCCSN progenitors that share structural similarities have almost spherical explosions with little metal mixing into the hydrogen envelope. A LMCCSN with less second dredge-up results in a highly asymmetric explosion. It shows efficient mixing and dramatic shock deceleration in the extended hydrogen envelope. Both properties allow fast nickel plumes to catch up with the shock, leading to extreme shock deformation and aspherical shock breakout. Fallback masses of ≲ 5×10⁻³ M_⊙ have no significant effects on the neutron star (NS) masses and kicks. The anisotropic fallback carries considerable angular momentum, however, and determines the spin of the newly born NS. The LMCCSN model with less second dredge-up results in a hydrodynamic and neutrino-induced NS kick of >40 km s⁻¹ and a NS spin period of ∼30 ms, both not largely different from those of the Crab pulsar at birth.
70 citations
TL;DR: In this article, the formation of turbulent collisionless shocks in conditions relevant to young supernova remnants is investigated. And the authors show that electrons can be effectively accelerated in a first-order Fermi process by small-scale turbulence produced within the shock transition to relativistic non-thermal energies, helping overcome the injection problem.
Abstract: Astrophysical collisionless shocks are among the most powerful particle accelerators in the Universe. Generated by violent interactions of supersonic plasma flows with the interstellar medium, supernova remnant shocks are observed to amplify magnetic fields1 and accelerate electrons and protons to highly relativistic speeds2–4. In the well-established model of diffusive shock acceleration5, relativistic particles are accelerated by repeated shock crossings. However, this requires a separate mechanism that pre-accelerates particles to enable shock crossing. This is known as the ‘injection problem’, which is particularly relevant for electrons, and remains one of the most important puzzles in shock acceleration6. In most astrophysical shocks, the details of the shock structure cannot be directly resolved, making it challenging to identify the injection mechanism. Here we report results from laser-driven plasma flow experiments, and related simulations, that probe the formation of turbulent collisionless shocks in conditions relevant to young supernova remnants. We show that electrons can be effectively accelerated in a first-order Fermi process by small-scale turbulence produced within the shock transition to relativistic non-thermal energies, helping overcome the injection problem. Our observations provide new insight into electron injection at shocks and open the way for controlled laboratory studies of the physics underlying cosmic accelerators. In laser–plasma experiments complemented by simulations, electron acceleration is observed in turbulent collisionless shocks. This work clarifies the pre-acceleration to relativistic energies required for the onset of diffusive shock acceleration.
58 citations
TL;DR: In general, the blast-induced ground shock excites the foundation of the structure prior to the air-blast pressure because of the obvious reasons of difference in wave propagation velocities as mentioned in this paper.
Abstract: In general, the blast-induced ground shock excites the foundation of the structure prior to the air-blast pressure because of the obvious reasons of difference in wave propagation velocities. Howev...
48 citations
TL;DR: A comprehensive survey on the field of forebody shock control devices is presented in this article, where the authors categorize the various forebody shocks control devices in a physics-based manner, explains the underlying physics for each device, and surveys the key studies and state-of-the-art knowledge.
46 citations
Posted Content•
TL;DR: In this paper, the main physical processes at the heart of the production of a nonthermal distribution in both Newtonian and relativistic astrophysical flows, namely the first and second order Fermi acceleration processes, are reviewed.
Abstract: This review aims at providing an up-to-date status and a general introduction to the subject of the numerical study of energetic particle acceleration and transport in turbulent astrophysical flows. The subject is also complemented by a short overview of recent progresses obtained in the domain of laser plasma experiments. We review the main physical processes at the heart of the production of a non-thermal distribution in both Newtonian and relativistic astrophysical flows, namely the first and second order Fermi acceleration processes. We also discuss shock drift and surfing acceleration, two processes important in the context of particle injection in shock acceleration. We analyze with some details the particle-in-cell (PIC) approach used to describe particle kinetics. We review the main results obtained with PIC simulations in the recent years concerning particle acceleration at shocks and in reconnection events. The review discusses the solution of Fokker-Planck problems with application to the study of particle acceleration at shocks but also in hot coronal plasmas surrounding compact objects. We continue by considering large scale physics. We describe recent developments in magnetohydrodynamic (MHD) simulations. We give a special emphasize on the way energetic particle dynamics can be coupled to MHD solutions either using a multi-fluid calculation or directly coupling kinetic and fluid calculations. This aspect is mandatory to investigate the acceleration of particles in the deep relativistic regimes to explain the highest Cosmic Ray energies.
45 citations
23 Mar 2020
TL;DR: In this paper, the main physical processes at the heart of the production of a nonthermal distribution in both Newtonian and relativistic astrophysical flows, namely the first and second order Fermi acceleration processes, are reviewed.
Abstract: This review aims at providing an up-to-date status and a general introduction to the subject of the numerical study of energetic particle acceleration and transport in turbulent astrophysical flows. The subject is also complemented by a short overview of recent progresses obtained in the domain of laser plasma experiments. We review the main physical processes at the heart of the production of a non-thermal distribution in both Newtonian and relativistic astrophysical flows, namely the first and second order Fermi acceleration processes. We also discuss shock drift and surfing acceleration, two processes important in the context of particle injection in shock acceleration. We analyze with some details the particle-in-cell (PIC) approach used to describe particle kinetics. We review the main results obtained with PIC simulations in the recent years concerning particle acceleration at shocks and in reconnection events. The review discusses the solution of Fokker-Planck problems with application to the study of particle acceleration at shocks but also in hot coronal plasmas surrounding compact objects. We continue by considering large scale physics. We describe recent developments in magnetohydrodynamic (MHD) simulations. We give a special emphasis on the way energetic particle dynamics can be coupled to MHD solutions either using a multi-fluid calculation or directly coupling kinetic and fluid calculations. This aspect is mandatory to investigate the acceleration of particles in the deep relativistic regimes to explain the highest cosmic ray energies.
42 citations
TL;DR: Direct evidence is presented for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale observations at the Earth's bow shock, which may provide a solution to the long-standing issue of electron injection.
Abstract: The first-order Fermi acceleration of electrons requires an injection of electrons into a mildly relativistic energy range. However, the mechanism of injection has remained a puzzle both in theory and observation. We present direct evidence for a novel stochastic shock drift acceleration theory for the injection obtained with Magnetospheric Multiscale observations at the Earth's bow shock. The theoretical model can explain electron acceleration to mildly relativistic energies at high-speed astrophysical shocks, which may provide a solution to the long-standing issue of electron injection.
TL;DR: Within a scramjet, the location of the shock train will change as the backpressure changes as discussed by the authors, and the engine usually goes in when the leading edge moves out from the entrance of the isolator.
Abstract: Within a scramjet, the location of the shock train will change as the backpressure changes When the shock train leading edge moves out from the entrance of the isolator, the engine usually goes in
TL;DR: In this article, the authors proposed a liquid carbon dioxide tube breaking technology and designed the relative device, which can meet the requirement of mainstream blasting safety criteria better than that of explosive blasting.
01 Dec 2020
TL;DR: In this article, a new manually operated pressure driven shock tube is proposed and demonstrated using acoustic method, which is used to measure both pressure and time lag of shock wave between the sensors.
Abstract: A new manually operated pressure driven shock tube is proposed and demonstrated. Shock wave-associated parameters like velocity, Mach number, pressure, and temperature are computed using acoustic method. Experiment involves manually loading train of pressure pulses into a driver tube using a bicycle pump. The high pressure buildup in driver tube ruptures the diaphragm at critical pressure and generates a propagating shock wave in the driven section coupled with sensor section in which a couple of microphones are separated by a fixed distance. The propagating shock wave acoustical profile is recorded and its arrival time lag is measured using sound recording software. In a conventional method, piezo-electric pressure sensors are utilized to measure both pressure and time lag of shock wave between the sensors. In the proposed method, microphones are utilized to measure time lag of shock wave with sampling frequency of 768 KHz using computer supporting audio software. Utilizing time data, the said shock wave parameters are evaluated and reported. The performance of the proposed shock tube is compared with manually operated piston-driven Reddy tube.
TL;DR: In this article, the authors performed large scale particle-in-cell simulations and magnetohydrodynamic-particle-incell (MHD-PIC) simulations to study electron acceleration in oblique shocks for larger transverse size and longer time scale.
Abstract: The origin of nonthermal emission observed from a variety of astrophysical objects is still a major unresolved issue in plasma astrophysics. Shocks at SNRs, with the help of a universal acceleration mechanism (i.e., diffusive shock acceleration; DSA), are widely believed to be the most probable acceleration sites of galactic cosmic rays (CRs). The underlying assumption of DSA is that only particles with Larmor radius much larger than the shock width can cross the shock and enter the acceleration process. This is especially challenging for thermal electrons due to their small Larmor radii. In non-relativistic quasi-perpendicular shocks without significant proton acceleration, whether electrons can be injected into DSA by self-driven upstream turbulence is not well-addressed in the literature. In this thesis, I try to answer this question by performing large scale particle-in-cell (PIC) simulations and magnetohydrodynamic-particle-in-cell (MHD-PIC) simulations. 1D PIC simulations show that electrons are injected into DSA through repeated cycles of shock drift acceleration (SDA) and the scattering of self-driven upstream waves. Multi-dimensional PIC simulations show different electron acceleration efficiencies with different background magnetic field geometries. 2D out-of-plane shocks are much more efficient in electron acceleration compared to in-plane shocks and the acceleration efficiency in 3D shocks lies in between 2D in-plane and out-of-plane shocks. I demonstrate that both the pre-acceleration at the shock leading edge and the corrugations at the shock ramp affect the electron acceleration efficiency. For the second half of my thesis, I apply MHD-PIC method to study electron acceleration in oblique shocks for larger transverse size and longer time scale. I develop a simple but more realistic electron injection prescription motivated by PIC simulations. The MHD-PIC simulations reproduce the most essential features of the shock structure and electron acceleration process. Quasi-perpendicular shocks can self-regulate how many particles they can take in response to different injection fractions by creating shock corrugations, making MHD-PIC model more robust for studying long term particle acceleration process without a detailed understanding of microphysics. By combing the results from both PIC simulations and MHD-PIC simulations, we can gain more insights into the physics of electron acceleration at different scales in astrophysical systems.
TL;DR: Caprioli et al. as mentioned in this paper used hybrid simulations to examine the non-linear feedback of the self-generated energetic particles (cosmic rays, CRs) on the shock hydrodynamics.
Abstract: Collisionless plasma shocks are efficient sources of non-thermal particle acceleration in space and astrophysical systems. We use hybrid (kinetic ions -- fluid electrons) simulations to examine the non-linear feedback of the self-generated energetic particles (cosmic rays, CRs) on the shock hydrodynamics. When CR acceleration is efficient, we find evidence of both an upstream precursor, where the inflowing plasma is compressed and heated, and a downstream postcursor, where the energy flux in CRs and amplified magnetic fields play a dynamical role. For the first time, we assess how non-linear magnetic fluctuations in the postcursor preferentially travel away from the shock at roughly the local Alfven speed with respect to the downstream plasma. The drift of both magnetic and CR energy with respect to the thermal plasma substantially increases the shock compression ratio with respect to the standard prediction, in particular exceeding 4 for strong shocks. Such modifications also have implications for the spectrum of the particles accelerated via diffusive shock acceleration, a significant result detailed in a companion paper, Caprioli, Haggerty & Blasi 2020, arXiv:2009.00007 [astro-ph.HE].
TL;DR: In this paper, the deformation response of polycrystalline Al microstructures at the atomic scale was investigated for various grain sizes and impact velocities (18-nm-100-nm) and simulations suggest an increase in shock front width and a decay in the velocity and the amplitude of the elastic precursor wave (Hugoniot elastic limit) as the wave travels through the microstructure.
TL;DR: In this article, the ignition probability of octahydro1,3,5,7,7-tetranitro-1,2,3-5,5-5tetrazocine-based polymer-bonded explosives was investigated.
Abstract: We investigate stochastic microcracks of a heterogeneous microstructure as the primary mechanism determining the non-shock ignition probability of octahydro1,3,5,7-tetranitro-1,2,3,5-tetrazocine-based polymer-bonded explosives. To quantify the ignition probability, we modify the viscoelastic cracking constitutive model by considering randomly distributed microcracks and combine this model with the hot-spot model and the Monte Carlo method. This method is validated by using a standard Steven test simulation, and we quantify how the microcrack stochasticity affects the ignition probability. The high-temperature region clearly changes compared with the case of single microcrack size. The discrepancy in the mechanical response of each element due to the heterogeneous microcracks causes a shear deformation, which increases the temperature. The difference between a uniform distribution and a normal distribution in microcrack size is also discussed. For a given impact velocity, the ignition probability for the normal microcrack size distribution exceeds that for the uniform microcrack size distribution. Although the two distributions have the same mean and variance, the real range in microcrack size corresponding to the normal distribution exceeds that for the uniform distribution. The results show that the sample radius does not significantly affect the ignition probability, whereas the opposite is true for the sample thickness. The ignition-probability curve is obtained in these cases. For sample dimensions of φ70 mm × 13 mm, φ98 mm × 13 mm, φ140 mm × 13 mm, and φ98 mm × 26 mm, the impact velocity thresholds corresponding to ignition probabilities in the range 0 %–99 % are 41.0–43.7, 41.0–44.3, 40.0–44.6, and 62.0–67.2 m/s, respectively, which is consistent with experimental results.
TL;DR: In this paper, a reusable composite negative stiffness (NS) structure composed of two-material systems is proposed and investigated, which is potential to be used in shock isolation, vibration control and deployable structure.
Abstract: Negative stiffness (NS) structures, as hopeful metamaterials, are potential in the energy absorption (EA) field. However, low specific energy absorption (SEA) limits its engineering application. In this paper, a novel reusable composite NS structure composed of Two-material systems is proposed and investigated. It is potential to be used in shock isolation, vibration control and deployable structure. Specimen was fabricated by additive manufacturing technology. Mechanical properties of this structure are studied with a combination of compression tests and simulations. Repeatability of the structure is then verified through cyclic compression. Besides, plate-impact tests were also carried out to study the cushion performance of this structure. The results of the impact tests reveal that the composite NS structure has good cushion performance by adjusting the threshold of acceleration response amplitude and completely reusable when the snap-through behavior occurs.
TL;DR: In this paper, the impact of interfaces on the spallation behavior of semi-coherent {111} Cu-Al multilayer is investigated by molecular dynamics simulations, and it is found that the resistance for dislocations to transmit through interfaces is determined by the coherency stresses, Koehler stresses and misfit dislocation at the interface.
TL;DR: Many energetic materials are unsuitable for practical purposes due to unacceptable sensitivity toward heat, impact, shock, or friction as discussed by the authors. In addition, chemical reactivity can also be of concern from...
Abstract: Many energetic materials are unsuitable for practical purposes due to unacceptable sensitivity toward heat, impact, shock, or friction. In addition, chemical reactivity can also be of concern from ...
17 Jun 2020
Abstract: This review paper discusses the recent progress in laser shock peening (LSP) of additively manufactured (AM) parts. LSP is an advanced post-processing technique that optimizes the service lives of critical components for various applications by inducing severe plastic deformation accompanied by the enhancement of surface properties in treatedmaterials.Material improvement is enabled through the generation of high-density dislocations, grain refinement, and beneficial phase transformations. Thesemechanisms produce highmagnitude compressive residual stresses which harden treated regions to depths exceeding 1mm.However, amajor roadblock for AMparts stems from the various fabrication processes themselves where detrimental tensile residual stresses are introduced during partmanufacturing, alongwith near-surface voids and cracks, all of which severely limit their applications. In addition to post-fabrication heat treatment that is typically required to homogenize themicrostructure and relieve the residual stresses of AMparts, post-processing surface treatments have also been developed tomanipulate the residual stresses of AMmaterials. Tensile residual stresses generated duringmanufacturing affect the fatigue life of AMmaterial negatively and could potentially surpass thematerial’s yield strength, resulting in acute geometric distortion. Recent studies have shown the potential of LSP tomitigate these stresses,modify themechanical properties of theAMparts, and to close near-surface voids and cracks. Furthermore, the thermal stability of favorablemicrostructuralmodifications in laser peenedAMparts, which allows for its use in high temperature environments, is not well understood and is currently limiting its effective utilization in these scenarios. Themain goal of this review is to provide the detailed insight needed for widespread acceptance of this technique as a post-processingmethod for AMmaterials.
TL;DR: The technical theory of LSP was summarized, which consists of the fundamental principle of L SP and the laser-induced plasma shock wave and the new technologies developed from LSP are introduced in detail.
Abstract: Laser shock processing (LSP) is an advanced material surface hardening technology that can significantly improve mechanical properties and extend service life by using the stress effect generated by laser-induced plasma shock waves, which has been increasingly applied in the processing fields of metallic materials and alloys. With the rapidly development of modern industry, many new technologies developed from LSP have emerged, which broadens the application of LSP and enriches its technical theory. In this work, the technical theory of LSP was summarized, which consists of the fundamental principle of LSP and the laser-induced plasma shock wave. The new technologies, developed from LSP, are introduced in detail from the aspect of laser shock forming (LSF), warm laser shock processing (WLSP), laser shock marking (LSM) and laser shock imprinting (LSI). The common feature of LSP and these new technologies developed from LSP is the utilization of the laser-generated stress effects rather than the laser thermal effect. LSF is utilized to modify the curvature of metal sheet through the laser-induced high dynamic loading. The material strength and the stability of residual stress and micro-structures by WLSP treatment are higher than that by LSP treatment, due to WLSP combining the advantages of LSP, dynamic strain aging (DSA) and dynamic precipitation (DP). LSM is an effective method to obtain the visualized marks on the surface of metallic materials or alloys, and its critical aspect is the preparation of the absorbing layer with a designed shape and suitable thickness. At the high strain rates induced by LSP, LSI has the ability to complete the direct imprinting over the large-scale ultrasmooth complex 3D nanostructures arrays on the surface of crystalline metals. This work has important reference value and guiding significance for researchers to further understand the LSP theory and the new technologies developed from LSP.
05 Aug 2020-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a post-treatment method combining heat treatment and laser shock peening was employed to alter the microstructure and mechanical properties of AM-processed Inconel 625 alloy (IN625).
Abstract: Although additive manufacturing (AM) has developed significantly due to its numerous process advantages, some adverse effects include large columnar grains and detrimental tensile residual stress, which can weaken the performance of the final part. In this study, a new post-treatment method combining heat treatment and laser shock peening was employed to alter the microstructure and mechanical properties of AM-processed Inconel 625 alloy (IN625). The microstructural evolution of IN625 after different treatments was studied. Results showed that many γ′' precipitates were formed after heat treatment. After heat treatment followed by laser shock peening treatment, gradient microstructure along depth direction was generated. High-density dislocation structures and refined grains were produced in the subsurface layer after heat treatment followed by laser shock peening treatment. Moreover, the precipitates interacted with dislocations. High levels of compressive residual stress could be generated after heat treatment followed by laser shock peening treatment, resulting in high ultimate tensile strength and large elongation. This combined heat treatment and laser shock peening method is helpful in enhancing the mechanical performance of AM parts through changing their microstructure and residual stress distribution.
TL;DR: In this article, the effect of cooling shock on the physical and mechanical properties of high-temperature granite samples was investigated, and the results showed that the higher the temperature of granite, the more significant change in wave velocity and apparent resistivity.
Abstract: Cooling shock has a significant thermal deterioration (TD) on the physical and mechanical properties of rocks in high-temperature conditions, which is a critical concern for the engineering application of the cyclic hydraulic fracturing technique in an enhanced geothermal system (EGS). In this work, cooling shock tests were carried out on granite samples to evaluate the actual TD of high-temperature rocks by cooling shocks, and multiple test methods were used to explore the effect of TD on the corresponding physical and mechanical properties of high-temperature granite. Some core conclusions from the study are as follows: (1) The wave velocity and apparent resistivity (AR) can reflect the thermal damage effect of cooling shocks on high-temperature granite. Notably, the higher the temperature of granite, the more significant change in wave velocity and AR. (2) The stress-strain curve tends to be smooth with the granite temperature increases and the cooling shocks intensify, the quiet period of acoustic emission (AE) events is lengthened, and the number is gradually reduced. (3) The TD effect of the cooling shock tends to be more significant for the samples at temperatures above 550 °C, and the peak stress continues to decrease with cooling shock strengthen. Furthermore, thermal stress is the main cause of TD to high-temperature granite. This study has the potential to guide the use of the cooling shock effect in extraction applications of geothermal engineering.
TL;DR: In this article, a successful implementation of fast-responding pressure and temperature-sensitive paints for study of hypersonic shock-body interaction between stage separation bodies was presented, and the complex flow structures due to shock body interaction were clearly visualized by PSP and TSP, which allowed detailed analysis on the effects of separation distance and inclined angle.
Abstract: This work presents a successful implementation of fast-responding pressure- and temperature-sensitive paints for study of hypersonic shock–body interaction between stage separation bodies. Fast PSP and TSP were applied symmetrically on two adjacent surfaces with a minimum separation of 5 mm, and the time-resolved pressure and temperature fields were obtained in a Ma = 6 flow using the intensity-based approach. The technical barrier of limited optical access was overcome through the development of translucent paints that allowed back-illumination and imaging through a glass wall. The in situ calibration was generally sufficient to remove the temperature-induced error for cases with weak/mild shock impingement on the surface. For cases with strong shock impingement and large temperature gradient, temperature correction was applied on the PSP data based on the TSP results prior to the in situ calibration. The PSP results with temperature correction showed good agreement with the transducer data. The complex flow structures due to shock–body interaction were clearly visualized by PSP and TSP, which allowed detailed analysis on the effects of separation distance and inclined angle.
TL;DR: In this article, a 2D underwater explosion (UNDEX) model is proposed to study cavitation characteristics near the water wave, where the effects of Stokes wave pressure are introduced into the cavitation model, and the influences of the water-wave profile on UNDEX loading characteristics are included in the present model.
TL;DR: In this paper, a series of experiments were conducted to investigate the influence of bifurcation structure in tubes on the spontaneous ignition of high-pressure hydrogen, and the results showed that the T-shaped structure has a significant influence on the occurrence of spontaneous ignition.