In order to investigate the influence of N-butyl-N-nitratoethylnitramine(Bu-NENA)on the energy and combustion properties of NC based propellants, energy properties was theoretically calculated by Russian Real software. The propellant samples were prepared by the method of absorption-extrusion technique. The density, detonation heat, specific volume, ignition delay time, burning rate were tested and the pressure exponent were calculated. The mechanism of the influence of Bu-NENA on the combustion performance of the propellant was analyzed by combustion waves, flame photographs and morphology of flameout surface. The results showed that the replacement of NG by Bu-NENA in NC based propellant reduces energy but increases gas production. The burning rate of propellants can be significantly reduced, with the decrease of more than 75% for 2MPa and the decrease of more than 64% for 20MPa. The pressure exponent was increased. Some catalysts used for NC/NG based propellants may fail in NC/Bu-NENA based system. The propellant ignition delay time is increased. The burning rate of the propellant is greatly reduced because of the volatilization of Bu-NENA during combustion and the decrease of thermal feedback caused by the decrease of combustion temperature.

To study the deflagration to detonation transition(DDT)of 3,4-dinitrofurazanfuroxan(DNTF), DDT experiments under four ignition conditions were carried out by comparing DNTF and Composition B explosive. The propagation process of reaction wave front in DDT tube was measured, and the influence of ignition charge on detonation transition distance and detonation transition time of DNTF was analyzed. The results show that DNTF can be ignited when the ignition charge amount are 2.0, 1.0, 0.5 and 0.25g, and finally transformed into stable detonation. With decreasing the amount of ignition charge, there is no significant change in the detonation transition distance of DNTF, which is in the range of 120—150mm, but the detonation transition time is greatly prolonged. Composition B explosive can only be ignited when the ignition charge amount is 2.0g, and the combustion to detonation process is not completed, showing that for DNTF explosive, different ignition conditions have significant effect on the low-speed heat conduction combustion stage in the DDT process.

Al/DAP-4 composite system was prepared by using ammonium perchlorate perovskite molecular energetic materials(DAP-4)as the main explosive. The thermal decomposition and combustion process of pure DAP-4 and Al/DAP-4 compounds were investigated by differential scanning calorimetry(DSC)and combustion test method. The results showed that with the decrease of the particle size and the increase of the content of Al powder, the decrease of peak temperature of DAP-4 thermal decomposition peak was more obvious. The thermal decomposition peak temperature of DAP-4 was decreased by 19.5℃ when adding 40% Al(100nm), indicating that nanoscale Al could promote the thermal decomposition of DAP-4. According to the results of combustion experiment made in air, the combustion intensity of DAP-4 was improved by using micron and nanoscale Al. With the increase of 500nm and 10μm Al powder content, the time to reach the flame front and sustained combustion of Al/DAP-4 increased obviously. The continuous combustion duration of Al/DAP-4 was 2.55 times than that of pure DAP-4 when adding 40% 100 nm Al particles.

Recent research progress of energetic combustion catalysts distinguished by energetic groups for solid propellant was reviewed. The catalystic combustion and mechanism of energetic combustion catalysts such as azoles, azines, ferrocene, dinitroanthraquinone, grapheme and nitro on the combustion of solid propellants and their main components were summarized. Several compounds of azole and azine had excellent catalytic effect on solid propellant, ferrocene and its derivatives can increase energy and improve migration, new types of energetic catalysts like dinitroanthraquinone also have their own advantages. The higher the nitrogen content, the greater contribution to the capacity of the catalyst system, and the nitrogen content can be increased and the performance of the catalyst can be improved by introducing energetic groups such as nitro on the nitrogen heterocycle. Finally, designing of multi-functional and multi-metal energetic combustion catalysts, exploring catalytic mechanism and strengthening the catalytic effect on the thermal decomposition of other energetic materials and the researches on the application of energetic combustion catalysts in solid propellant were pointed out as the emphasis directions in the future. With 89 references.

The chlorinated 1-dodecyl-3-methylimidazolium chloride([C₁₂C₁Im]Cl)was prepared by N-acylation and compared with sodium dodecyl sulfate(SDS)and mixed acid(concentrated sulfuric acid to concentrated nitric acid in the volume ratio of 3:1 )in terms of carbon nanotubes(CNTs)pretreatment and loading effect of copper oxide(CuO)nanoparticles. The molecular structure of [C₁₂C₁Im]Cl was investigated by ATR-FTIR, the microscopic morphology of the CNTs after different pretreatments was carried out by SEM, and the mechanism of CuO loading on CNTs was analyzed by XPS. The results show that [C₁₂C₁Im]Cl is synthesized successfully, [C₁₂C₁Im]Cl contains a positively charged imidazolium hydrophilic group and SDS contains a negatively charged sulfate hydrophilic group, which can be used as a cationic surfactant and anionic surfactant for surface pretreatment of CNTs, respectively. The CNTs pretreated with [C₁₂C₁Im]Cl have a clear tubular shape, smooth walls, no agglomeration and excellent dispersion. CuO is anchored on the defective sites of the CNTs, making CuO stable on the CNTs surface. After pretreatment with [C₁₂C₁Im]Cl, CuO/CNTs combustion catalysts with a CuO mass fraction of 46.40%, uniform distribution state and high binding strength are obtained.

In order to investigate the complex combustion process of metal particles, a 25kHz high-speed digital off-axis holographic imaging system was built to study the time-resolved three-dimensional visualization of typical phenomena of particles during Al/AP/HTPB propellant combustion. The typical combustion phenomena of Al particles in propellant combustion were analyzed by 3D visualization, including the flaking of particles on the combustion surface of propellant, the micro-explosion of particle clusters, and the existence of wake flame surface of burning particles. Time-resolved three-dimensional reconstruction of the observed aluminum particles is performed by high-speed off-axis holography as well. The results show that off-axis holography technique eliminates the interference of twin images and can obtain clear reconstructed images of particles. Its independently configured reference light largely eliminates the influence of flame on light propagation and effectively suppresses the aberration caused by the sharp change of refractive index around the particles. The high-speed off-axis holography has strong practicality and broad application prospects in the visualization and diagnosis of solid propellant combustion.

In order to explore the influence of pressure and oxygen concentration on the ignition and combustion characteristics of aluminum particles, a self-built visual pressurized flow-carrier reactor combined with high-speed micrograph method, based on a flat flame burner, is used to investigate the microscopic combustion process of the 79μm discrete single aluminum particle over the pressure range of 0.1—0.7MPa and 20% or 30% oxygen concentration of O₂/CO₂ atmosphere. The results indicate that the combustion process of aluminum particles can be roughly divided into four stages: the preheating and slow oxidation stage, the intense combustion stage of aluminum vapor diffusion stage, the acceleration stage of crushing and bursting rotation, and the burnout stage. When the pressure increases by 0.2MPa, the ignition delay time of aluminum powder reduces by about 4ms and the combustion duration increases by about 2ms. When the oxygen concentration increases by 10%, the ignition delay time of aluminum powder at different pressures decreases by about 1.5ms, and the combustion duration increases by about 0.2ms. With the increase of pressure and oxygen concentration, the oxygen partial pressure and oxygen concentration on the surface of aluminum particles increase, and the combustion is more intense, which shortens the total time of aluminum particles, and the effect of pressure is more obvious than that of oxygen concentration.

To solve the problem of difficult ignition and poor combustion performance of boron particles, the effects of different particles and blending ratios on ignition and combustion characteristics of boron-based composite metal fuel were explored using a single particle experiment. The main combustion products were detected and analyzed by the energy dispersive spectrometer(EDS)and scanning electron microscopy(SEM). The combustion temperature distributions were measured by the two-color pyrometry method. The results show that the combustion process of boron and boron-based composite metal particles is mainly divided into two stages including ignition and combustion stage. The addition of aluminum, carbon nanotubes, and graphene reduces the ignition delay time and combustion time. The influence of ignition delay time is increased with the increase of blending ratios. Moreover, the addition of nano-aluminum has the greatest effect on the ignition delay time of the composite fuel. The addition of carbon nanotubes and graphene has the greatest effect on the combustion time. The temperatures of the boron nanoparticles are measured and mostly distributed at 1772K. The addition of nano-aluminum increases the combustion temperature of single particle to 1830K, while the addition of nano-iron decreases the combustion temperature of single particle to 1680K. The addition of graphene and carbon nanotubes has little effect on the combustion temperature.

To explore the ignition and combustion characteristics of tetramethylammonium octadecahydro-eicosaborate((Me₄N)₂B₂₀H₁₈), the compound was obtained by the oxidation of decahydrodecaborate anion, and its combustion heat was measured using an oxybomb calorimeter, and a high-speed camera and infrared thermal imager were used to record the flame phenomenon and the surface temperature on the combustion process of the sample. In combination with the pyrolysis behaviors of the compound in nitrogen and air atmospheres, the combustion process of the(Me₄N)₂B₂₀H₁₈ was evaluated. The results show that the actual density of the(Me₄N)₂B₂₀H₁₈ was measured at 0.96g/cm³, and the(Me₄N)₂B₂₀H₁₈ exhibits high thermal stability, which decomposes at above 250℃ in the nitrogen atmosphere. While in the air atmosphere, an evident mass increment was present at 300℃ after a mass loss at 240—300℃. The combustion heat of the(Me₄N)₂B₂₀H₁₈ is 55.5MJ/kg. This compound presents good ignition combustion performance, and it burns in air with a green characteristic flame. Its surface temperature can reach 1100℃ during the combustion process.

To study the flow field evolution mechanism for the whole process of ignition, quenching, reinitiation, and stabilization in a continuous detonation engine, the in-house solver BYRFoam based on the open-source computational fluid dynamics platform OpenFOAM is adopted. The array of injection holes and the geometry of the hollow combustor with a Laval nozzle are used. The process of ignition and quenching and the cause of reinitiation are analyzed. The flow field evolution mechanism for the whole process of ignition, quenching, reinitiation, and stabilization is summarized by the spatio-temporal distribution method. The results show that the oblique shock wave at the initial stage of ignition will be reflected in the contraction section of the tail nozzle to form a reflected shock wave, which enters the fresh gas and forms a new detonation wave opposite to the initial detonation wave, causing the detonation wave to quench. Following quenching, the high pressure at the head of the combustor will hinder the entry of fresh gas, then the gas is gradually discharged from the combustor through the tail nozzle, and the pressure at the head of the combustor is reduced. The gradual introduction of fresh gas into the combustor creates the conditions for reinitiation. There are two possible reasons for the resumption of continuous detonation waves. One is that the reflected shock wave at the contraction section of the tail nozzle enters the fresh gas layer and evolves into a detonation wave. The other is that the formed detonation wave interacts with the array of injection holes to form reversed shock waves, which enters the fresh gas and evolves into detonation waves. Detonation waves finally propagate stably after the reinitiation due to the interaction and evolution of detonation waves, shock waves, and fresh gas.

The features of five levitation technologies in normal gravity environment, namely pneumatic levitation, electric levitation, magnetic levitation, optical levitation and acoustic levitation, were summarized and compared. The research progress of combustion of levitated solid fuel particles and liquid fuel droplets in recent years were well reviewed. It is pointed out that levitation eliminates the heat conduction between the sample and the carrier during combustion, which is desired to capture the relatively accurate information about the evolution of substances and the release of energy at the microscopic scale, and obtain the intrinsic combustion characteristics of substances. Among the above-mentioned levitation technologies, optical levitation has the advantages of wide application range of substance, precise control of the levitation position of particles/droplets, good levitation stability and easy integration with other diagnostic devices, and is the most promising one in a variety of levitation techniques in the field of combustion of energetic materials. In future work, it is proposed to strengthen the characterization of the chemical composition of the products of the single-particle/droplet combustion process, expand the research scope of levitation combustion technology in the field of energetic materials, and carry out research on the combustion characteristics and interaction mechanism of multi-particle and multi-droplet energetic materials. 44 References were attached.

To more efficiently develop the single-atom catalysts, it is essential to deeply characterize the single-atom catalysts structure and study their catalytic mechanisms at the molecular and atomic scale. Herein, this paper reviews the advanced techniques for charactering the structure of single-atom combustion catalysts, including synchrotron-radiation based X-ray absorption spectroscopy(XAS)and spherical aberration-corrected transmission electron microscopy. Meanwhile, synchrotron-radiation based operando and in-situ techniques are introduced, including XAS, Fourier transform infrared(FTIR)and synchrotron vacuum ultraviolet radiation photoionization mass spectrometry(SVUV-PIMS), which could play vital roles in unravelling the reaction mechanisms. These advanced structural characterizations to investigate the existence of single-atom catalysts and their catalytic mechanisms would significantly provide a new vision for the design and synthesis of single-atom combustion catalysts. Furthermore, current challenges and future research directions of these characterization techniques in single-atom combustion catalysis are presented. 38 References are included.

To increase the burning progressivity and internal ballistic performance of small arms gun propellants, multi-hole gun propellants with 4-perforations are deployed, and the static & dynamic combustion performance are investigated. A closed-bomb is used to test the static combustion performance, and 5.8mm testing guns are used to test the dynamic combustion performance. The results show that, without deterring, the progressivity of 4-perforated gun propellant is better than that of oblate ball and 1-perforated gun propellants. The muzzle velocity of oblate ball and 1-perforated gun propellants are 17m/s and 40m/s lower than that of 4-perforated gun propellant, respectively. The light transmittance of oblate ball and 1-perforated gun propellants are 18% and 15% lower than that of 4-perforated gun propellant, respectively. The static and dynamic results show that 4-perforated gun propellants have better progressivity and internal ballistic performance than those of oblate ball and 1-perforated gun propellants.

To investigate the effect of the rupture form of end cap of the modular cartridge on the dispersion characteristics of propellant grains during the ignition and flame spreading processes, a 3D unsteady state gas-solid two-phase flow model was established based on computational fluid dynamics-discrete element method(CFD-DEM), and the dispersion characteristics of propellant grains was numerically simulated under different perforation modes of end cap of the modular cartridge. The simulation results show that the propellant grains presents a combined accumulation form with gentle slope section, plain section and steep slope section with different accumulation parameters from the primer side to the pressure control diaphragm side. With the circular sector increased from 60° to 120°, the axial length of gentle slope and horizontal accumulation increases from 269mm to 320mm, the average particle thickness of horizontal accumulation increases from 18.1mm to 22.8mm, and the proportion of steep slope particle accumulation decreases from 70.3% to 65.1%. The broken of the end cap at the under part contributes to more distribution of grains at gentle slope section and plain section along the axial direction, and less accumulation at steep slope section. The broken of end cap at left side and right side leads to almost the same distribution of grains along the axial direction in terms of axial length, thickness and proportion of accumulation at steep slope section. While the proportion of accumulation of propellant grains at steep slope is slightly lower when the cap broken on one side.

In order to investigate the propagation characteristics of detonation wave of coaxial binary charge, two kinds of coaxial binary charges with typical structures were prepared by using two aluminized explosives with C-J detonation velocity difference of 1.81mm/μs. The evolution of detonation waveform and sliding detonation velocity were obtained by high-speed scanning method and electrical measurement method respectively, and the distribution of waveform characteristics and normal detonation velocity were analyzed. The results show that the evolution of detonation waveform mainly occurs in the slower explosive, and when the waveform becomes stable, the axial velocity of the slower explosive(DNAN-based aluminized explosive DRLU)is equal to that of the faster explosive(DNTF-based aluminized explosive DOL). When the slower explosive is located in the inner layer, its waveform is converging, and according to the trend of increasing normal detonation velocity, it can be divided into initial region, overdriven region and convergent region. The normal detonation velocity of the initial region is lower than the C-J detonation velocity, and its mass ratio is about 36%. The mass of the convergent region is the lowest of 5%, but its detonation intensity is the highest. When the slower explosive is located in the outer layer, its waveform is divergent, and it can only be divided into the initial region and overdriven region. The mass ratio of its initial region is about 77%, and the normal detonation velocity of the overdriven region is only slightly higher than its C-J detonation velocity.

In order to analyze the competitive reaction of different metal phases in the combustion process of aluminum alloy, thermogravimetric differential scanning calorimetry(TG-DSC)was used to analyze the oxidation performance of Mg-Al binary alloy, and an X-ray diffractometer(XRD)was used to analyze the phase composition of the samples before and after reaction, and scanning electron microscope(SEM)was used to observe the morphology of the samples, and self-made combustion system was used to study the combustion process of Mg-Al alloy powder in the air. The results show that Mg in the alloy is oxidized faster than Al when the alloy powder is heated slowly with a rate of 10℃/min in air, and the preferential reaction of Mg couldn't block the oxidation of Al, and their products further react to form MgAl₂O₄. The formation of MgAl₂O₄ becomes more obvious when the temperature is higher than 800 ℃. When Mg-Al alloy is burned in air, the micro-explosion phenomenon can be observed, and only nitrogen can reach the reaction zone of liquid Al due to the preferential combustion of Mg with oxygen, and it leads to that the Al in the alloy matrix only reacts with nitrogen to form AlN. Therefore, the different reaction processes indicate that the reaction heat of Al has a great difference. When Al is converted into AlN in the combustion process of Mg-Al alloy, the reaction heat decreases greatly(about 12kJ/g), which is only 40% of the value when Al is oxidized to Al₂O₃.

In order to study the process and mechanism of deflagration to detonation transition(DDT)of propellants, explosives and their charges, a real-time measurement method of wave velocity during DDT process, microwave phase-shifting velocity measurement method, is explored. Its basic principle is to accurately measure the shifting of microwave frequency and phase caused by the movement of wave front during DDT process, and further the movement velocity of wave front in real time is obtained. The composition, calibration method, test design and program of the measurement system are described. The method was applied for the DDT process of high energy nitramine gun propellant, and important rules during the DDT process were obtained. The causes of DDT of high-energy gun propellant were discussed. The results show that the microwave phase-shifting velocimetry has strong anti-interference ability, high sampling frequency and large amount of information, which makes up for the shortcomings of traditional measurement technologies(such as ionization probe technology). By using this method, the information of wave velocity and displacement during the DDT process of a high-energy nitramine gun propellant were obtained, and the main stages, characteristic data and variation law of the DDT process before sample tube burst were accurately clarified, which could provide important technical support for the DDT control research of high porosity propellant charge.

To analyze the fracture behavior of steel #45 rods under the effects of detonation wave interaction, a detonation wave interaction effect experiment was carried out. Force distribution on the rods and fracture process were analyzed through numerical simulation. The initiation effect of mode, initiation distance and charge height on the fracture characteristics of the rod fracture process was analyzed. The numerical simulation results were verified by experiment. The results show that a superimposed detonation wave produces a narrow pressure-enhancement zone, which results in a 1mm-depth notch on the experiment target. The initiation mode affects the force distribution on the rods. When the initiation point is at one end of the booster,the peak pressure on the rod near the initiation point is obviously lower than that on the other rods,and when the initiation point is at the center of the booster,the time of the rod subjected to the detonation wave is more concentrated and the pressure is similar. When the ratio of charge height and initiation distance is between 0.75 and 1.25, under the interaction of the superimposed detonation wave, the pressure on the rod increases with the increase of the charge height or the detonation distance.The effect of initiation distance on the detonation wave superimposed pressure is more obvious than that of initiation position and charge height.

To study the fracture behavior of tungsten alloy fragments driven by detonation, 93W-Ni-Fe was taken as the research object and the static crushing properties, dynamic mechanical properties and fracture properties after the detonation of tungsten alloy fragments prepared by two different processes were tested. The scanning electron microscope was applied to metallographic study. Combining the original fragments and the recovered fragments after detonation loading, the integrity prediction of fragments after detonation loading was realized. The results show that the dynamic stress-strain curve and the crushing rate after detonation loading are obviously different even though the static crushing properties of the two kinds of fragments are equivalent. Therefore, the static crushing test is not enough to characterize the detonation driving integrity of fragments. However, it is found that the fragments with no obvious strain hardening behavior in dynamic stress-strain curve are more likely to be broken. Meanwhile, there are a lot of pores and uneven grain distribution in the micro morphology of fragments. The results show that the dynamic mechanical property analysis can effectively predict the detonation driven fracture behavior of tungsten alloy fragments.

The physical mechanisms of shock initiation, developments of macro-/mesoscopic reaction flow models, numerical simulations at meso-/trans-scale and continuum scale for heterogeneous solid explosives, and shock initiation experiments and measuring technologies were reviewed, some new findings and opinions from authors and team coworkers were summarized, and the future development trend was pointed out to deepen the understanding of the physical mechanism of shock initiation in heterogeneous solid explosives, and provide methods and technical means for charge safety design. As a typical complex dynamic process, the onset of shock initiation of heterogeneous solid explosive is the result of multiple hot-spot formation mechanisms. However, the existing chemical reactive rate models, generally considering some one single hot-spot formation mechanism, are unsuited to the high-fidelity calculation of shock initiation process. Although the pressure-dependent reaction rate model adapts to the changes of mesostructure within certain range, it fails to physically correctly describe the desensitization or sensitization, the corner effected dead-zone phenomenon of explosives under complicated loadings such as the multiple shock-wave loading and ramp-shock combined loading, while the entropy- or temperature-dependent models are suitable for complex loadings, but don’t consider the accurate prediction of structural response at meso-scale. Developing the multi-mechanism coupling hot-spot ignition model and the wide-ranging reaction rate model with high accuracy has been an important direction of the reaction flow model. The mesoscopic experimental diagnosis technology with high resolution and fast response has long been a technical difficulty in detonation field, thus the mesoscale modeling is the main method to investigate the shock initiated hot-spot formation mechanisms. The trans-scale modeling of shock initiation from mesocale to macroscale has been preliminarily realized, which is an important trend in the simulation of the shock initiation and detonation of heterogeneous solid explosive. With 151 references.

In order to investigate the effect of different particle sizes of ammonium perchlorate (AP) on the thermal stability of RDX and the effect of AP on the energy release rule of RDX-based composite explosives, AP/RDX composite explosives with different AP content and particle sizes were designed, and their heat of explosion and detonation velocity were tested. The results show that the AP with particle sizes of 100-150 μm, 10-13 μm and 2 μm all have acceleration on the decompostion of RDX, and the decomposition peak temperature of RDX decreases from 433℃ to 368℃, 417℃ to 365℃ and 375℃ to 321℃, respectively with the decrease of particle size of AP. As the addition of AP particle and its size decreases, the apparent activation energy of RDX in the mixtures decreases from 206 kJ/mol to 188, 170 and 157 kJ/mol, respectively. With the mass fraction of AP increases from 0 to 60%, the detonation velocity and heat of explosion increase from 5 390 m/s to 8 315 m/s and from 1 610 kJ/kg to 5 396 kJ/kg, respectively. As the particle size of AP decreases, the detonation velocity increases to 5 863, 5 902 and 5 931 m/s, respectively, while there is no significant impact on the heat of explosion.

A kind of coaxial binary composite charge was prepared by means of DNTF based explosive with high detonation velocity to wrap aluminized explosive with high heat of detonation. Its detonation waveform characteristics were studied by high-speed scanning method and the difference in driving characteristics of the composite charge and single charge was compared through cylinder test. Results show that because the difference of steady detonation velocity of the two kinds of explosives is 1.8 mm/μs, it makes the detonation waveform of the inner layer charge appear obvious convergence effect, boost its wave front propagation velocity, also cause the detonation reaction zone width decrease and reduce the energy released by the composite charge. The specific kinetic energy at beginning of the expansion of the product is 0.095 kJ/g lower than that of the single explosive charge, then in the middle and late stage of product expansion, it is still 0.06 kJ/g lower. However, after the relative molar volume of the product increases to 1.95, the product pressure exceeds the single charge with high detonation velocity, and when the relative molar volume increases to 3.07, the product pressure is only slightly lower than the single charge with low detonation velocity.

To improve the explosion power and the pressure resistant properties of emulsifying seismic bomb, and reduce the environmental pollution and safety hazards, a kind of hydrogen storage type emulsifying seismic bomb was designed using emulsion explosive sensitized compositely by TiH₂-glass microsphere as the initiating explosive grain, and emulsion explosive sensitized chemically by MgH₂ as the main charge. The explosion power of TiH₂-glass microsphere sensitized emulsion explosive and the explosion power and the pressure resistant properties of MgH₂ sensitized emulsion explosive were studied by compression experiments, detonation velocity tests, underwater explosion experiments, and shock wave pressure experiments, respectively. The results show that compared with the traditional emulsifying seismic bomb, TiH₂-glass microspheres sensitized emulsion explosive in hydrogen storage type emulsifying seismic bomb has high explosion power, the compression amount of lead column is 23.80 mm, reaching military explosives brisance and at the same time the detonation velocity is 4 659 m/s, it is suitable to be used as initiating explosive grain instead of TNT explosive grain. MgH₂ sensitized emulsion explosive has high explosive power and good compressive resistance, the peak pressure, specific impulse and shock wave total energy were respectively increased by 8.7%, 12.4% and 33.0% compared with the traditional glass microsphere sensitized emulsion explosive, which is suitable for main charge instead of the main charge of emulsion explosive. The use of hydrogen storage type emulsifying seismic bomb instead of the traditional seismic bomb has a good application prospect.

By analyzing the stress state of double-layered cubical/spherical prefabricated fragments under the typical arrangement and combining the release law of detonation driving energy, the acceleration process of double-layered fragments was divided into two stages, namely, shock acceleration stage and expansion acceleration stage of gas product. The acceleration process of fragment in the shock acceleration stage was measured by flash X-ray photography, the acceleration effect of gas product expansion was calculated by classical Gurney formula. The experimental and theoretical analysis of the double-layered cubical/spherical fragments of typical tungsten and steel materials were carried out. The results show that the initial velocity of the outer layer fragments is higher than that of the inner layer fragments, wherein, the ratio of the initial velocity of the inner and outer layered cubical steel fragments is the largest, which is about 1.48, and the outer layered cubical steel fragments is obviously damaged due to the strong tensile wave action. The ratio of the initial velocity of the inner and outer layered spherical tungsten fragments is the smallest, which is only 1.08. Moreover, the spherical fragments are mainly subjected to the symmetrical force from the inclined sides, so that it is difficult to form a stronger and more concentrated tensile wave, resulting in better integrity of the outer fragments.

A novel emulsion explosive is developed using clay particles as an inert additive. Its detonation velocity and brisance were measured by probe method and lead cylinder compression method, respectively. The mechanism of clay particles to reduce the detonation velocity of the emulsion explosive was analyzed. The underwater detonation parameters of different formulas were tested by underwater explosion experiments. The results show that when the mass fraction of clay particles is 0-20% and the mass fraction of grass microspheres is 5%-15%, the detonation velocity of the novel emulsion explosive is 2 815-4 420 m/s and the brisance is 7.9-18.9 mm. The empirical formulas of detonation velocity and brisance of the novel emulsion explosive obtained by fitting experimental results are D=4 923.1-9 930a-2 980b(m/s) and Δh=23.3-74a-20b(mm) respectively, of which, a and b are the mass fraction of clay particles and grass microspheres, respectively. The results of the underwater explosion experiments reveal that the clay particle content has a significant influence on the results of underwater detonation parameters. When the mass fraction reaches 20%, the peak over pressure, shock wave impulse, specific shock wave energy, specific bubble energy and specific total energy of novel emulsion explosive decrease by 33.34%, 13.19%, 67.67%, 71.73% and 70.96%, respectively, compared with traditional emulsion explosives.

To estimate the deflagration to detonation transition (DDT) process of explosives composed of common components,three kinds of composite explosives,P1(40% TNT/60% RDX),P2(40% DNTF/40% HMX/10% TATB/5% Al/5% additives) and P3(25% DNTF/40% AP/30% Al/5% additives) were prepared by melting-casting technology,and explosive P4(30% RDX/30% AP/30% Al/10% additives) was prepared by casting technology.The DDT test for the four kinds of explosives were carried out by the coaxial ionization probe test technology,and the DDT response characteristics of four kinds of explosives were analyzed by the broken status of DDT tube,wave front propagation velocity in the DDT process and detonation transition distance.The results show that the DDT of explosives P1,P2 and P3 takes place and the detonation transition distance is 750-825 mm,375-450 mm and 675-750 mm,respectively,while the DDT of explosive P4 does not take place.For the brokenness of DDT tube,explosive P2 is the most violent,explosive P3 is second and explosive P1 is the smallest,indicating that the broken extent of DDT tube is positive correlation to the detonation pressure of explosive and if the formulation contains the ingredients that the thermal decomposition temperature is approaching,the thermal decomposition energy can be added quickly,and causes the combustion to be unstable,then increases DDT.The casting technology can decrease the possibility of DDT due to the presence of inert additives on the isolation coating and absorption action of explosive components.

To study the influence of micro-/nano-scaled aluminum/RDX paticle gradation on the wave front curvature effect of aluminized explosives,the steady wave shapes and the corresponding detonation velocities of the RDX-based aluminized explosives with different micro-/nano-scaled aluminum/RDX particle gradation under normal temperature environment were measured by optical waveform scanning and electrical probe measuring velocity method,and based on the experimental results,the function relation between the normal velocity (D_n) and the local curvature (κ) of the detonation wave front of explosives was analyzed.The results show that using micro-/nano-scaled Al/RDX paticle gradation,the bending degree of wave front is significantly reduced and the normal detonation velocity affected by the curvature is weakened,in which,the waveform of micro-/nano-scaled RDX with mass ratio of 50:25 or micro-/nano-scaled Al with mass ratio of 15:5 is flat,their maximum curvatures are about 0.013、0.014 mm^-1,respectively,and the maximum decrease of the normal detormation velocity compared with steady detonation velovity are 0.03 and 0.04 mm/μs,which is equivalent to 56% and 61% of the conventional micrometer samples,reflecting that the loss of the wave front energy is smaller due to the lateral flow.

To explore the application of B/Al compound powder in thermosetting plastic bonded explosive, six kinds of HMX based explosives containing boron (B) and aluminum (Al) were designed and prepared by adding oxidizer ammonium perchlorate (AP), B/Al compound powder and binder hydroxyl-terminated polybutadiene (HTPB). Three kinds of Φ50mm explosive cylinders containing B/Al with shell and without shell were prepared respectively. The spring electric pin method was applied to measure detonation velocities of explosive cylinders with shell and without shell respectively. The detonation pressures were calculated by the experienced formula and relative dent depth method respectively, the influence of B/Al compound powder content on detonation property was discussed. The results show that the explosives GH-4, GH-5, GH-6 are solidified by manual casting, the densities of Φ50 mm explosive cylinders are between 1.530-1.570 g/cm³, the detonation velocities are between 6.900-7.400 mm/μs, and the detonation pressures are about 19 GPa, the manual casting is suitable for screening of explosive formulas; While the explosives PF-1, PF-2 and PF-3 are solidified by void vibration casting, the densities of Φ50 mm explosive cylinders are about 1.693 g/cm³, the detonation velocities are between 7.800-8.000 mm/μs, and the detonation pressures are about 24 GPa. The explosive PF-3 with B/Al compound powder mass ratio of 1:1 and mass fraction of 20%, the combination effect of metalized explosive leads a little of B/Al compound powder to take reaction in reaction area, comparing to other formulas, the detonation velocity and detonation pressure of explosive are higher. It indicates that the spring electric pin method can be an additional method for detonation velocity measurement, and it can be adopted if copper foil electric pin method can’t be taken.

The curvature effect experiments were carried out for the insensitive JBO-9021 explosive grain with different radius (5.0,7.5 and 15mm) and different initial densities (1.894g/cm³-1.901g/cm³) at ambient temperature by using the high-speed streak camera and electric probes, and the steady-state detonation front shape and wave velocity were obtained and the change with density and radius of explosive grain was analyzed. Results show that, with increasing the initial density of JBO-9021 explosive from 1.894g/cm³ to 1.901g/cm³, the steady-state wave velocities of detonation wave for three kinds of JBO-9021 explosive grains with different radius increase, the steady-state front shape becomes flatter and the difference of the wave arriving time between the center point and edge point of front becomes smaller. In the range of small curvature (κ<0.2mm^-1), the relationship between the normal wave velocity D_n and the local curvature, (D_n(κ)),for detonation wave front of JBO-9021 explosive is not affected by the radius and density of the explosive grain. For larger curvature of κ>0.2mm^-1, the D_n(κ) relationship reveals a discrete trend with the radius and density of the explosive grain. The initial density and radius of JBO-9021 explosive grain affect the D_n(κ) relationship of great curvature for detonation wave front of explosive together.

To reduce the difficulty of predicting the detonation products and solving detonation parameters, the equilibrium compositions of detonation products were achieved by linear combination of the basic feasible solutions, which were obtained from the mass conservation equations; and the detonation parameters were further obtained based on equilibrium compositions. The major process was executed as follows:the basic feasible solutions were selected out by the principle of minimum free energy, and the initial solution was given by the principle of largest heat release. The equilibrium compositions of detonation products were linearly searched by uniting the initial solution with the basic feasible solutions, and the above-mentioned operation steps were completed by using self-made program. The parameters of the BKW equation of state were adjusted applying the linear support vector machine (SVM), and its main steps were introduced in detail. The detonation products and parameters of PETN, CL-20 and aluminized explosives were predicted with this method, and after parameter adjustment, it is found that the predicted results and the experimental ones are in better agreement. In comparison with the detonation experiment data of single compound, it is found out that when the BKW equation parameters are adjusted, the energetic materials with more similar percentage of gas fraction in detonation mass to the explosives predicted should be used as the training set of the LS-SVM model. If the detonation parameters of aluminized explosives are predicted, it should use the Al/O ratio close to measured explosive to train the SVM model.

The effects of contents of main componens  RDX and AP for p(BAMO-AMMO) thermoplastic high energy propellants, AP sizes and gradation on the response law of deflagration to detonation transition (DDT) were investigated by DDT tube method. The results show that under the same experimental conditions, the DDT response takes place in propellants containing 65%(mass fraction)  AP ,while the popellants containing equal amount of RDX only occur combustion reaction. When the mass fraction of RDX increases from 65% to 85%, the sample occurs transfortion from combustion reaction to DDT reaction. The trendency of DDT occurrence for propellant containing equal amount of fine AP with d₅₀=1.0[KG-*9]μm is lower than that of propellant containing coarse AP with d₅₀=105μm. When the mass ratio of coarse and fine AP gradation is 10∶3, the DDT reaction of p(BAMO-AMMO) propellant does not happen.

The molecular geometries, electronic structures，theoretical density and heat of formation of nitro derivatives of pyrido-dicycloureas were obtained by Gaussian 03 program at DFT-B3LYP/6-31G** level. The values of detonation velocity and detonation pressure were obtained using KamletJacobs equations. Results show that the compounds 1,3,5,7-tetranitro-5,7-dihydrodiimidazo-［4,5-b:4′,5′-e］pyridine-2,6(1H,3H)dione and 8-amino-1,3,5,7-tetranitro-5,7-dihydrodiimidazo［4,5-b:4′,5′-e］-pyridine-2,6(1H,3H)-dione have good detonation properties, but the structures of compounds 1,3,5,7-tetranitro-2,6-dioxo-1,2,3,5,6,7-hexahydrodiimidazo［4,5-b:4′,5′-e］pyridine-4-oxide,1,3,5,7,8-pentanitro-2,6dioxo-1,2,3,5,6,7-hexahydrodiimidazo［4,5-b:4′,5′-e］pyridine-4-oxide and 8-amino-1,3,5,7-tetranitro-2,6-dioxo-1,2,3,5,6,7-hexahydro diimidazo［4,5-b:4′,5′-e］pyridine-4-oxide are unstable. The molecular symmetry, steric hindrance and hydrogen bonds are three main factors affecting their molecular stability.

The steady state wave shapes and detonation velocities of CL-20based and RDX-based aluminized explosives with same Al content were measured by a high speed scanning camera and electrical probe measuring velocity method. The function relationship between the normal velocity (Dn) and curvature (κ) of the detonation wave front of explosives was analyzed. Results show that the detonation wave front of CL-20based aluminized explosive is flat than that of RDXbased aluminized explosive. The effect of curvature effect on normal detonation velocity of CL-20based aluminized explosive is smaller than that of RDX-based aluminized explosive. When κ>0.005mm^-1, the reduced rate of Dn of CL-20based aluminized explosive is obviously less than that of RDXbased aluminizedexplosive. When κ<0.005mm^-1, the reduced rate of Dn of CL-20based aluminized explosive is slightly higher than that of RDX-based aluminized explosive.

The propagation velocity of the shock wave in the JO-9159 explosive sample and the aluminum sample was detected by a high-speed scanning camera. Hugoniot relations of the overdriven detonation product of JO-9159 explosive were obtained by the antitheses method. The overdriven detonation state of explosive was described by a combination equation of JWL and γ. The parameter values of equation of state (EOS) of overdriven detonation products for JO-9159 explosive were determined based on the experiment results. The results indicate that the p-V curve of the EOS is well consistent with the experimental results. The overdriven detonation state of explosive may be more accurately described by the combination equation of JWL and γ.

The effect of particle injection velocity on the two-phase flow field of a rotating detonation engine fueled by aluminum powder and air is studied. The two-dimensional rotating detonation combustion for the aluminum particles with the injection temperature of 300 K and the high temperature air with the total inflow temperature of 900 K is simulated by using the discrete phase model, one-step surface reaction including kinetic/diffusion-limited rate surface combustion model and multiple-step gas phase decomposition reaction model and considering the devolatilization of incompletely unburned particles. Results show that the particle injection velocity near the inlet is lower than that of air, which results in an incomplete overlap between the air triangle and the particle triangle. As the particle injection velocity increases from 1 m/s to 100 m/s, the detonation velocity and temperature first decreases and then increases. There is a significant temperature difference between particles and air injected into the combustion chamber, which leads to unstable detonation wave propagation. The detonation wave has the best stability when the particle injection velocity is 70 m/s.

In order to study the characteristics of rotating detonation flow field in annular combustor and the effects of boundary layer, viscosity and turbulence simulation methods on the flow field structure, the open source computational fluid dynamics software OpenFOAM is used to simulate the three-dimensional model of rotating detonation engine （RDE） with hydrogen as fuel and air as oxidant. The characteristics of rotating detonation flow field obtained by Euler equation, large eddy simulation (LES) method and Reynolds-averaged Navier-Stokes (RANS) method are compared and analyzed. The flow field structure from LES simulation is emphatically discussed. The results show that the temperatures of flow fields in the inner, middle and outer sections exhibit no appreciable difference when the slip boundary is applied. However, when the no-slip boundary is utilized, the temperatures of the inner and outer walls are higher than that of the middle section, and the boundary layer will affect the flow velocity of gas in a region close to the wall. As a result, the height of detonation wave on the inner and outer walls is lower than that in the middle section. The boundary layer also affects the flow state of the combustion products, leading to the deformation of wave front on the axial section. The rotating detonation flow field structures obtained by different turbulence simulation methods are similar, indicating that the viscosity is the main factor affecting the rotating detonation flow field structure. The findings are highly significant in terms of elucidating the mechanism by which the viscosity and the boundary layer affect the rotating detonation process.

To explore a technical way to effectively suppress the propagation of high-power detonation noise generated by a pulse detonation engine to the key parts of the engine head, the external flow field of pulse detonation engine equipped with three kinds of reflectors,which are ellipsoidal reflector,parabolic reflector and conical reflector,are numerically simulated by using the space-time conservation element and solution element method.The results show that the three types of reflectors have varying effects on the detonation noise due to their distinct reflection characteristics onthe rotating surface.The ellipsoidal reflector converges the reflected wave towards the axis of the reflector.The parabolic reflector approximately parallelizes the reflected waves downstream, whilethe conical reflector does not produce the reflected wave lagging behind the direct wave,which strengthens the direct wave and propagates downstream together.

To study the phase transformation mechanism of carbon nanotubes during detonation, synthesis experiments were carried out using direct detonation method with carbon nanotubes as the additional carbon source. The detonation product was chemically purified. X-ray diffraction (XRD) was used to characterize the purified product, and it was found that the product consisted of diamond. The purified product was characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and after in-depth analysis, it was found that the carbon nanotubes transformed into diamond through solid in situ phase change during the detonation process. Multiple cores were observed on a carbon nanotube to form crystals at the same time. When adjacent crystals came into contact, crystal boundaries were formed, limiting growth in specific directions to form polycrystals. Depending on the circumferential, radial and axial dimensions of the formed diamond crystals, as well as the number and position of the crystals in the formed polycrystals, polycrystalline diamond particles of different shapes such as tubes, flakes, and blocks were obtained.

The inhomogeneity of the medium in front of the waves has a significant effect on the propagation of gaseous detonation waves, but the interaction mechanism remains unclear. The two-step induction-exothermic reaction model is used to study the propagation characteristics of one-dimensional hydrogen/air detonation waves in a non-uniform medium, and the influence of perturbation wavelength on detonation waves under different oscillation modes is analyzed. The results show that as the perturbation frequency get closer to the inherent oscillation frequency of detonation waves, the inherent instability is more easily triggered, resulting in more irregular oscillations. There are two dominant mechanisms of detonation waves propagating in a non-uniform medium. Pressure oscillation of weakly unstable detonation waves are dominated by density perturbation, and the main frequency of detonation pressure oscillation is consistent with the perturbation frequency; the pressure oscillation of strong detonation waves are dominated by inherent instability, and the oscillation frequency is distributed in the low frequency region without obvious dominant frequency, where perturbation only enhances the oscillation amplitude. When the perturbation is applied, the detonation waves under atmospheric pressure and at high altitudes has the above oscillation characteristics, which further confirms the feasibility of regulating detonation waves by artificial perturbation.

To effectively promote the intermetallic reaction between Al and Ti, two types of core-shell structured nanocomposite fuels have been prepared by using the high-energy ball milling method, namely Al/Ti@AP/NC and Al/Ti@PVDF/CL-20. The quality of the coating layers of AP/NC and PVDF/CL-20 on the surface of Al/Ti is inspected by scanning electron microscopy (SEM). The thermal reactivity, heat of reaction and combustion performances of Al/Ti-based composite fuels are evaluated by DSC/TG thermal analyses, a bomb calorimeter, and a customized combustion diagnostic system. The morphologies and compositions of the condensed combustion products (CCPs) are characterized by SEM and X-ray diffraction (XRD) techniques, respectively. Results show that the core-shell structured Al/Ti@AP/NC and Al/Ti@PVDF/CL-20 could be obtained by high-energy ball milling method. The thermal decomposition of the energetic composites is enhanced with the introduction of Al/Ti. Furthermore, the intermetallic reaction between Al and Ti, burning rate, and the combustion wave temperature could be enhanced with the inclusions of AP/NC or PVDF/CL-20. In particular, for the composite fuel coated with AP/NC, the burning rate (246.6mm·s^-1) is increased by 9.5 times and the combustion wave temperature (1703.2℃) is 59.3% higher compared to that of pure Al/Ti (the burning rate and combustion wave temperature are 23.5mm·s^-1 and 1069.3℃, respectively). The compositions of the CCPs depend on the types of energetic coating layers, which are dominated with AlTi₂C and Ti(O_0.19C_0.53N_0.32), indicating that chemical reactions occur between Al/Ti and energetic composites during the combustion process.