The multiphase detonation model of plasma jet ignition is calculated by the two-dimensional viscous CE/SE method. The influence of viscosity on the detonation flow field under the condition of the plasma jet is analyzed through N-S equation and Euler equation. The influences of differentignition temperatures and time of the jet and initial droplet radius on the process of deflagration-to-detonation transition (DDT) are analyzed. The calculated results show that the viscosity has a very small effect on the propagation of detonation wave, while has some effects on the detonation parameters. DDT distance can be significantly shortened by improving the initial jet ignition temperature and time. When the plasma jet has fully ignites explosive mixture, a continual increase in jet time has little effect on the decrease in the distance of DDT. When the droplet radius is less than 50 μm，the peak pressure of detonation wave increases with the increase in droplet radius. When the droplet radius is more than 50 μm, the peak pressure of detonation wave decreases with the increase in droplet radius.

Based on the JWL equation of state of detonation products and Taylor fracture criteria, a model considered the expansion details about energy conversion and fragment initial velocity is derived from conversation of energy. The cylinder tests of three materials, including copper, 45^# steel and 6061 aluminum alloy, driven by TNT explosive are made, and the inflation track and velocity are analyzed. The experimental results show that, by comparing with Gurney formula which is considered only to express the driving ability of the explosion parameter, the proposed model considers the driving factors, inflation process and mechanics function of meta. The result is of pertinence and applicability.

A new energetic ionic salt—triaminoguanidinium 5,5′-bistetrazole-1,1′-diolate salt is synthesized based on glyoxal and guanidine hydrochloride. The structure of triaminoguanidinium 5,5′-bistetrazole-1,1′-diolate salt is characterized by using FT-IR，¹H NMR， ¹³C{¹H} NMR spectra and elemental analyses. Its optimized structure，IR spectrum and thermodynamic parameters are obtained at the DFT-B3LYP/6-31+G^**theoretical level. Its detonation properties and thermal decomposition are also predicted by the formula of Kamlet-Jacobs. The results show that the density， heat of formation， detonation velocity and detonation pressure are 1.78 g/cm³，710 kJ/mol， 9.01 km/s and 34.88 GPa，respectively.

A series of experimental study of continuous rotating detonation engine(CRDE) with orifice-slit injection mode, which utilizes H₂ as fuel and air as oxidant, were carried out to study the influence of oxidant injection area on the propagation characteristics of continuous rotating detonation wave . Based on the high-frequency pressure signal in the combustion chamber and the pressure signal in the oxidant chamber, the influence of oxidant injection area on the propagation, velocity loss, stability and wavefront height of detonation wave is analyzed in detail. The experimental results show that, when the mass flow rate of propellant remains constant, the loss of propagation velocity of detonation wave becomes larger, the stability of propagation velocity of detonation wave becomes worse, and the wavefront height of detonation wave decreases with the increase in oxidant injection area. When the oxidant injection area is 217.1 mm²and the equivalent ratio is 0.9, the average velocity of detonation wave reaches 1 800 m/s,which is 93% of the theoretical Chapman-Jouguet (CJ) velocity, and the stability of detonation wave is also the best. When the oxidant injection area remains constant, the stability of detonation wave first increases and then decreases with the increase in equivalence ratio. Key

A gas-liquid two-phase detonation model with chemical reaction is established in cylindrical coordinates based on the conservation element and solution element method, and the three-dimensional numerical simulation of continuously rotating detonation engine is performed to investigate the propagation characteristics of gas-liquid two-phase continuously rotating detonation wave. The flow field structure and stable propagation of detonation wave at initial formation stage were obtained through the calculation. Meanwhile, the variation of flow field in the radial direction and the thrust performance are analyzed, and the propagation characteristics of two-phase detonation wave are revealed. The simulated results show that the flow field structure in the combustion chamber is consistent with the experimental results in Ref.\[4\]. Because of the convergence of outer wall and the divergence of inner wall, the detonation strength increases along the radial direction of the combustion chamber. The self-sustaining rotating propagation of detonation wave is realized. When the injection pressure and injection temperature are 0.2 MPaand 288.15 K,respectively, and the fuel droplet radius is 25 μm, the average thrust of the gasoline and oxygen-enriched air continuously rotating detonation engine is about 880 N, and the propagation frequency of detonation wave is about 4 390 Hz. Key

In order to reveal the detonation propagation characteristics of DNAN (2,4-dinitroanisole)-based melt-cast explosives, and speed up the application of the explosives, the critical diameter of DNAN-based aluminized melt-cast explosives is measured by continuous wire method. The measured results demonstrate that the critical diameter of DNAN-based aluminized melt-cast explosives decreases with the increase in wt% of aluminum (0~30wt%) and the decrease in particle sizes of both aluminum (d₅₀:6 μm, 12 μm, 31 μm) and RDX (d₅₀:19 μm, 147 μm, 751 μm), and increases with the decrease in crystal quality of RDX. The investigation can provide a basic reference for both the formulation of DNAN-based aluminized melt-cast explosives and the warhead design.Key

Based on the problems of tantalum materials in the application of multi-mode warhead, the feasibility study on the formation of dual-mode damage element by detonation-driven tantalum liner is conducted. The dynamic properties of tantalum materials were tested by Hopkinson bar test. The effects of tantalum liner structure parameters (cone angle, radius of curvature and wall thickness) on the formation of EFP and JPC are studied by LS-DYNA finite element software. It is found out that the range of each parameters of optimum dual mode damage element for the formation of the cone angle is 140°-150°, the radius of the arc is 0.45-0.55 times of charge diameter, and the wall thickness is 0.02-0.024 times of charge diameter. The optimum structure parameters of the tantalum liner warhead are determined by the orthogonal design, and X-ray imaging test is carried out. The experimental results are in good agreement with the simulation results, the error are controlled in 15%, and the actual penetration depth is raised to 55.4% compared to Cu. It is proved that Ta is suitable for the liner of multi-mode warhead. Key

In order to study the temperature and pressure effects of the detonation wave generated by dust clouds in the surrounding environment and its damage law, the two-phase flow model and space-time conservation element and solution element method are used to simulate the propagation of 3.0 m radius detonation wave in the air, which is formed by uniformly distributing the suspended aluminum dust with the equivalence ratio of 1 and the particle radius of 2 μm. The pressure reaches tomaximum of 2.10 MPa when the detonation wave arrives at 3.0 m from the boundary of cloud, and then the pressure will decrease. The reaction of aluminum dust particles is completed without surplus at 4.7 m from the boundary of cloud. The fireball formed by the dust reaction move outwardsto reach at 10 m from the boundary of cloud. The central area of fireball is a high-temperature and low-density area with temperature of above 3 500 Kand density of 0.120 kg/m³. The overpressure reaches to 0.10 MPa when the propagation distance of shock wave arrives at 24.5 m from the boundary of cloud. The overpressure reaches to 0.09 MPa when the shock wave arrives at 28.0 m from the boundary of cloud, which can cause serious injury to the human body. Key

In order to investigate the gasoline/oxygen-enriched air continuously rotating detonation engines(RDE), the conservation elements and solution elements method (CE/SE method) based on the unstructured triangular meshes is used for the simplified 2D simulation of two-phase continuously RDE. The different propagation modes of rotating detonation waves (RDW) were obtained. The influences of total inlet pressure and equivalent ratio were studied and the operating performance of RDE was analyzed. The results show that the evaporation and stripping of droplets delay the combustion of fuel, which leads to the incomplete coupling of detonation peak pressure and peak temperature. The equivalent ratio has a great influence on the propagation mode of rotating detonation waves. A single-wave RDW is easily generated under low equivalent ratio,and a multiple RDW is generated under higher equivalent ratio. The detonation wave pressure and velocity fluctuations of single-wave mode are the smallest, those of double-wave mode are moderate and those of three-wave mode are the largest, but the thrust fluctuation law of propagation mode is opposite to that of pressure fluctuation. The thrust fluctuation of single-wave mode is the largest, followed by double-wave mode, and the thrust fluctuation of three-wave mode is the smallest. The calculated velocity and flow field of the rotating detonation agree well with the experimental results. The numerical research is meaningful for the development of unstructured-mesh CE/SE method. The calculated results have a guidance effect on the experimental research and engineering application of two-phase RDE. Key

The aluminum/air and hydrogen/air rotating detonation engines (RDEs) are experimentally studied and compared to reveal the specific detonation characteristics and propulsion performance of aluminum powder RDE.The RDE engines work at the equivalence ratio of 1 and the air mass flow rate of 260 g/s. It's found that the thrust of aluminum/air RDE is 35% higher than that of hydrogen/air RDE; the pressure peak of aluminum/air is 11% higher than that of hydrogen/air; the detonation velocity of aluminum/air is 11% lower than that of hydrogen/air; and the detonation propagation mode of auminum/air is the same as that of hydrogen/air, which are single wave mode. The above differences are not only caused by the different properties of fuel，but also caused by the difference between the gas-solid two-phase detonation and the gaseous detonation. The experimental results could provide a feasible solution for the air breathing aluminum powder RDE and establish a foundation for the solid powder RDEs.

In order to reveal the detonation properties of 2,4-dinitroanisole（DNAN）-based melt-cast explosives and promote the application of this kind of explosives, a computer code is used to calculate the detonation properties of three DNAN-based melt-cast explosives. A series of experiments are carried out to characterize the properties of the DNAN-based explosive (DNAN 20/HMX 80) and Octol. Electrometric method is used to test the detonation velocities and pressures of the two explosives. Explosive probability method is used to test the mechanical sensitivities of the two explosives. Laser interferometer velocimetry (VISAR) is used to test the free surface of copper bar drived by the detonation products. The results show that the detonation properties (detonation velocity is 8 436 m/s and pressure is 31.23 GPa) of DNAN-based explosive (DNAN 20/HMX 80) are better than those of Octol. The mechanical sensitivity of DNAN-based explosive (impact sensitivity is 33% and friction sensitivity is 57%) is lower than that of Octol. The speed of the copper bar drived by the detonation products is 3 045 m/s. The comprehensive performance of DNAN-based explosive (DNAN20/HMX80) is better than that of Octol. The DNAN-based explosive could replace Octol for air defense warhead, antimissile warhead, and large-caliber EFP warhead.

Spin detonation of cast charges TNT-DINA and DNT-PETN was studied. Detonation param?eters of the systems are capable of propagation in the form of spin-pulsating detonation at low frequencies. All such systems appear to have a detonation velocity DJ of 7. 3 ?7. 4 km/s and practically the same explo?sion heat Qv=(5.40±0.01) MJ/kg. The calculated velocity and pressure (PJ) of detonation vs. content of sensitizer were analyzed and shock temperatures were calculated by means of the SW computer code. A pressure (P3) and a temperature (T3) in the peripheral zone where damping and reinitiation of detonation take place were estimated. The PJ values for TNT-RDX mixtures are higher than those for TNT-DINA blends with the same content of sensitizer RDX or DINA. Accordingly the temperature T3 for the former system is 60?100 K higher than that for the latter. Experimental data are in good agreement with calculat?ed results.

A rotating detonation engine（RDE） was test to study the initiation and propagation characteristics of kerosene fuel rotating detonation wave. The inner diameter, outer diameter and length of RDE annular combustor are 120 mm, 153 mm and 240 mm, respectively. It is ignited by a hydrogen/oxygen micro-pulse detonation engine with kerosene and oxygen-rich air used as fuel and oxidant, respectively. The initiation process and propagation of gas-liquid two-phase rotating detonation wave, and the operation characteristics of engine are analyzed from high-frequency pressure signals in combustor. The test results indicate that the reactivity of mixtures plays an important role on the initiation of detonation wave. When the content of oxygen in the oxidant is low, the reactivity of the mixture is low, and the rotating detonation wave fails to be initiated. It is until the oxygen content increases to 39.2% that the rotating detonation wave can be formed. The rotating detonation wave always propagates in two-wave collision mode with the wave velocity range of 815-920 m/s after successful initiation. The velocity of detonation wave tends to rise with the increase in equivalence ratio under lean fuel condition. The engine mainly works in a deflagration mode when the mass flow rate of air is more than 822 g/s. Key

The JWL EOS parameters of detonation products for high explosives are generally determined by the cylinder test. However, the cylinder test is not suitable for fuel air explosives (FAE), which is cloud-like in a macro state. A method for calculating the EOS parameters based on the experimental data of FAE detonation in external field is established to determine the JWL EOS parameters of FAE detonation products. Aback propagation neural-based genetic algorithm (BPNN-GA) is introduced into the method. The calculated values are compared with the data from the single- and multi-source external field experiments. The research shows that the introduction of BPNN-GA can simplify the EOS parameter optimization process and also improve the speed and accuracy. Based on the obtained JWL EOS parameters of FAE, the single- and multi-source FAE cloud detonation models are established. The profile of shockwave front from the simulation is consistent with the morphology of actual detonation shockwave. The maximum deviations between simulated and experimental values of the ground peak overpressure at the 50 m measuring points from single- and multi-source are 9.0% and 11.1%, respectively.

In order to explore whether the drawn-molded oxygen-free copper tube meets the ductility requirements of standard cylinder test, a standard copper tube for SymbolFA@25 mm cylinder test was made of coarse-grained soft oxygen-free copper without secondary forging by using the drawing process. The high-speed framing camera and scanning camera were used to observe the expansion and fracture processes of copper tube under detonation loading of TNT and JO-159 explosives, and compare the difference of fracture strain and the direction of crack propagation in the typical high strain rate range. The influence of strain energy of copper tube on the characterization parameters of driving performance of explosive was also analyzed. The results show that the cracks of copper tubes are mainly formed and expanded along the busbar and the fragments are mainly strip-like under the detonation loading of TNT explosive. However, under the detonation loading of JO-159 explosive, a more complicated staggered state arises in the fracture zone, and the copper tube expands to form dense small fragments. The main reason for this phenomenonis that the circumferential and axial strain rates of copper tubes under detonation loading of JO-159 explosive are 1.34 and 2 times of those under detonation loading of TNT. Under the detonation loading of these two kinds of explosives, the fracture diameter reaches 3 times of the initial diameter, and the Gurney speed, which characterizes the driving performance of explosives, is not changed significantly. Therefore, the copper tubes can meet the requirements of the general high-energy explosives for cylinder test. Key

The ring-shaped arrangement continuous rotating detonation engine, in which the mixture of gasoline/oxygen-enriched air is injected, is test. The propagation characteristics, time-domain characteristics, frequency-domain characteristics and detonation height of self-sustained detonation wave under two-wave collision mode are analyzed in detail. One-dimensional thrust of the engine model under two-wave collision mode is measured. The experimental results show that the detonation has an average frequency of 2.174 kHz and an average velocity of 1 051 m/s, the detonation wave height is between 55 and 70 mm, the effective thrust is 607.3 N, the thrust per unit area is 8.587×10⁴ N/m², and the fuel specific impulse is 735.1 s under the operating conditions of 0.82 equivalence ratio, 945.3 g/s oxygen-enrichedair (34.3%O₂ and 65.7% N₂) and 84.3 g/s gasoline. It shows that the engine thrust under two-wave collision mode fluctuates obviously, the thrust oscillates around the average thrust, and the vibrationfrequency of engine and the propagation frequency of detonation wave are basically identical at the stable phase in the thrust curve. Key

The arriving time of the metal flyer at some point was measured by two kinds of combined probes for checking their uniformity. Meanwhile, the free-surface velocity and displacement of the metal flyer were measured by double-sensitive VISAR for contrast with combined probes. Experiment results show that the first stage probe of the vertical combined probe coincides well with the horizontal combined probe; the second stage probe has a little difference with the horizontal combined probe; the difference increases along with the stage of vertical combined probe, and the reason is the interference of the probe on the flyer. The maximum differences at the measuring point 1 between two kinds of combination probes and VISAR are 0.71% and 0.67% respectively, and the maximum differences at point 2 are 0.98% and 0.90% respectively. Two kinds of combined probes can be used together to acquire more data in the experiments.

The detonation parameters of RDX-based aluminized explosive were measured by test, and the test result was verified by KHT code. The influence law of Al/O ratio on detonation pressure, detonation velocity and heat was analyzed. Underwater explosion experiments were carried out on shock wave propagation and bubble pulse of 1kg cylindrical RDXbased aluminized explosive under water 4.7m.The coefficients of similitude equation for peak pressure and attenuation time constant were fitted. The study indicates that the detonation pressure and velocity reduce linearly with the increasing of Al/O ratio and the detonation heat achieves a maximum value when Al/O ratio equals to 0.997. When Al/O ratio equals to 0.366, the peak pressure and shock wave energy reach the maximum value, but the shock wave impulse and flux density reach the maximum value when Al/O ratio equals to 0.633, and the first bubble pulsation period and radius reach the maximum values when Al/O ratio equals to 0.997.

In order to improve the thrust of air-breathing pulse detonation engine, the air-breathing pulse detonation engines with central cone-scales valve (CCSV) and central cone-blunt valve (CCBV) are investigated, and the force condition of multi-cycle air-breathing pulse detonation engine during working is analyzed. The results show that the average thrust of multi-cycle air-breathing pulse detonation engine can be accurately measured by using the piezoelectric force sensor. Furthermore, the average thrust of air-breathing pulse detonation engine with CCSV is 2.05 times as high as that of the engine with CCBV at 10 Hz. For this point of view, the results are significant to the direct measurement of the thrust of multi-cycle air-breathing pulse detonation engine and the improvement of the propulsion performance of air-breathing pulse detonation engine.

Different types of dependent uncertainties exist in detonation system since the random vibration of physical parameters in measurement technique, and the equation of state (EOS) and the reaction rate equation are empirical modeling. And these random variables are not independent and identically distributed. Assessing the impact of these input uncertainties on the output result of system has important theoretical significance and practical value. The corner effect in detonation diffraction is studied. The non-intrusive polynomial chaos based on regression method is used for uncertainty quantification. Rosenblatt transformation is used to transform the dependent random variables into independent random variables satisfying standard uniform distribution. Under-determined linear equations are derived from the sampling method. Optimization method is chosen to solve the regression equation. The basis pursuit is applied to change the optimization problem into linear programming. The expectation and confidence interval of velocity components, horizontal positions, and pressures of two Lagrangian reference points near the corner are given by using the method mentioned. The results show that the trajectories of two Lagrangian reference points are dramatically different although they are not far from each other. It is difficult to judge the long time dynamical behavior since the uncertainty is becoming large over time. The method can also be applied to other detonation problems. Key

The expansion fracture process and intrinsic physical mechanism of metal cylinder driven by detonation are researched for calculating the initial velocity of fragments. In the experiments, 50SiMnVB steel and 45 steel cylindrical shells with different thickness were driven by TNT explosive detonation. The image information of expansion and the history of velocity were obtained by using a high-speed framing camera and the arrayed photonic Doppler velocimetry. Experiments reveal that the oscillation of expansion velocity is due to shock wave loading, and the expansion velocities of metal cylindrical shells continue to increase after shell rupture. The experimental results show that, for the shells with the same density, the oscillation amplitudes and pulsation times of expansion velocities of the shells increase with the increase in thickness，and the rupture mode changes from pure shear to tension-shear mixing. Because of the different load coefficients caused by different thicknesses of shells, the rupture time of 45 steel shell is later than that of 50SiMnVB steel shell, and with the increase in shell thickness, the difference between rupture time and rupture radius is larger. However, due to the acceleration of detonation products after rupture, the final expansion states of the two steel shells with the same wall thickness are almost the same. Key

Numerical simulation was carried out to investigate the structures and instabilities of deflagration and detonation waves induced by an incoming flow of stoichiometric H₂/air premixed gas with Mach Number 6.5 over a cone with half cone angle 32°,based on the multi-component Euler equations with chemical reactions. The reliabilities of numerical model and computational grid were verified using the experimental results in Literature［7］. The numerical results show that the combustion induced by conical shock wave includes both detonation and deflagration modes. Both the modes, which can alternately appear, show the regularly spatial instability and the temporally periodic oscillation instability. The regularly spatial unstable detonation is regarded as a coalescence of the basic triple wave structures, while the unstable deflagration shows a zigzag reaction front. In an oscillation combustion period, the evolution of detonation and deflagration modes is affected by triple wave structure, thermodynamics of unburned gas in the reaction induction region and disturbance of reflected waves from wall, and shows the distinct phenomena ofwhich the chemical reaction induction length increases along the cone wall during the deflagration process and decreases during the detonation process. The results are significant for the combustion chamber design of scramjet or standing detonation engine.

A fixed-interface Level Set method is proposed for the deviation of interface position caused by reinitialization. The basic idea of the fixed-interface Level Set method is to construct a condition that keeps the interface immobile in the process of reinitializing the two adjacent iterations, thus deducing the calculation formula for the smooth parameters. The proposed method is used to correct the fixed smooth parameters to the changed smooth parameters. The numerically simulated results show that, compared with the traditional Level Set method, the fixed-interface Level Set method can fix the interface position well in the process of reinitialization, and the mass conservation is improved. The fixed-interface Level Set method effectively avoides the deviation of detonation wavefront caused by error accumulation. It is suitable for solving the propagation problem of detonation wavefront. Key

In the numerical simulation of gaseous detonation process with the detailed chemical reaction mechanism, the computation of chemical source term takes a large amount of CPU times due to the stiffness and nonlinearity of the term. To improve the computational efficiency without the loss of the computational accuracy for chemistry computation, two algorithms of in situ adaptive tabulation (ISAT) based on multi-threaded parallel integration (MPI) are proposed to replace the original direct integration (DI) method, and then applied in the computation of two-dimensional gaseous detonation process for H₂/O₂ medium with detailed chemical mechanism. In the parallel algorithms, two types of tabulation, namely the local tabulation for each processor and the global tabulation for all processors, are proposed, and the effect of the tabulation mode on the computational efficiency is investigated. Further, the influences of error criterions and numerical schemes on the computational efficiency of the algorithms are also examined. The results show that both the proposed algorithms can provide satisfactory computational accuracy compared with the results of DI, and the computational efficiency of the local tabulation for each processor with the chemical speedup ratio of 2.17~2.43 is higher than that of the global tabulation for all processors. The proposed parallel accelerated algorithms can not only accurately describe the propagation process of two-dimensional gaseous detonation wave, but also improve the parallel computational efficiency of of chemically reactive flows.Key

As an effective approach to improve the thrust performance, the nozzle plays an important role in the control of formation and propagation of pulse detonation engine noise. The experimental system of pulse detonation engine is set up to investigate the formation and control method of detonation noise. The detonation noise characteristic of pulse detonation engine with three nozzles is studied. The results show that the convergent-divergent nozzle has the most significant influence on pulse detonation engine noise to reduce the noise amplitude by 77.13% in 0 ° direction and at 3 000 mm. Large convergence angle would lead to obvious directivity for convergent nozzles. The obvious directivity would be also obtained by divergent and convergent-divergent nozzles with small exit area. The convergent-divergent nozzle with 48 mm throat diameter and the divergent nozzles with 280 and 320 mm exit diameters have the significant impact on reference radius which is reduced from 1 600 mm to 800 mm . The results are of great significance for studying the mechanism of detonation noise and expediting the process of the engineering application.

In order to study the moving and combustion conditions of powder, and the firing and flame propagation characteristics of the charge structure which has overload protection with ignition by detonation, an axial symmetry two dimension-two phase flow model of the layered charge structure using the ignition by detonation was set up based on the experimental study. The main parameters of ignition process were calculated using programming language, and some typical computed results were listed, such as pressure distribution pattern and solid phase void ratio distribution pattern. From the analysis of firing and flame propagation characteristics of the ignition process, it is concluded that the layered charge structure has nicer flame propagation characteristic.

To the glancing detonation wave propagating along a charge covered with a cover plate, an analytical model for the parameters of the shock wave going along the cover and charge is presented. Combined with the critical power of the shock initiation, the cover critical depth is obtained. Some test tesults are given.

The rotating detonation in a circular combustion chamber was numerically simulated by using a simplified 9-species, 19-step reaction model based on the three-dimensional Euler equations with chemical reaction. The numerical calculation method used is based on a second-order spatially wave propagation algorithm and a two-step Runge-Kutta time marching algorithm. The calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera. The three dimensional flowfields induced by a continuous rotating detonation and the distinctive features of the rotating detonations were described in detail. The calculated result shows that the detonation wave can rotationally propagate along the combustible mixture layer, and the lateral rarefaction waves from the air and the previous detonation product lead to the detonation deficit.

The regular oblique reflection and Mach reflection of detonation waves in condensed explosive after their interaction are investigated using the three-wave theory and the Whitham's method on the basis of Jones-Wilkins-Lee (JWL) equation of state (EOS). The JWL EOS-based calculation model of regular oblique reflection, reflection pressure and Mach stem height is derived. A theoretical calculation method is proposed for the slowly changed function k(ξ) in the modified Whitham's method. The calculation model was verified with the experimental data of PBX 9501 and JH-2 explosives. The calculated results are in good agreement with the experimental results, which means that the calculation model based on JWL EOS can be used accurately to predict the detonation parameters distribution and propagation process of regular oblique reflection and Mach reflection. Key

In order to study the impact of different air inlets on detonation process and operating frequency of pulse detonation rocket engine (PDRE) which uses fuel/air as a propellant, three kinds of air inlets, i.e. tangential inlet, tangential/radial mixing inlet and tangential/radial/axial inlet combination, were designed and test on a 80 mm diameter detonation tube, and the multi-cycle work of PDRE was successfully implemented. The results show that the operating frequency and detonation wave of PDRE can be improved by increasing the number of air intakes and setting a reasonable inlet way; the flow speed can be enhanced and the explosive mixture can be evenly distributed in space by using the tangential/radial inlets which achieve the detonation stability at a frequency of 15 Hz. The results have an important reference value to the overall design of optimized PDRE.

A simplified virial equation of state based on Lennard-Jones 6—12 potential called VLW EOS is proposed for detonation products. The detonation properties of explosives composed of CHN〇，CN〇，HNO, N〇，HN， CHNOF，and CHNF have been calculated with this equation，and the results are compared with experimental data, and with results computed with BKW EOS and LJD EOS. The principal feature of this approach is that the third and the fourth virial coefficients can be conveniently obtained from the well known second one. It is shown that the agreement between the predicted detonation parameters and the experimental data is reasonably satisfactory.

Experimental results of Deflagration to Detonation transition (DDT) in high packed energetic granular bed are presented in this paper. According to the observed phenomena，a mathematical model describing DDT is established based on the two-phase flow theory，and some constitutional relations in the model are improved. The physical process accompanied with strong shock wave are numerically solved by using MacCormack scheme and self-adaptive grid technique. The predicted convective flame front，predetonation length，and detonation velocity coincide basically with our experimental data，and its results are in agreement with our mechanism analysis of DDT published in reference I.

A method for the study of non-steady detonation behaviours for the explosives in the reaction zone—the wedge PMMA technique is proposed in this paper. It has been used successfully for such purposes. Its advantages are： true description of detonation behaviours for the explosives，simple experimental technique and better precision (about 2-3%). The determination of behaviours in tke reaction zone for the explosive requires only one trial. The detonation bekaviotirs as measured by the wedge PMMA technique for explosives of Tariotis thicknesses show that there exists nonsteady detonation in tke PBX-HMX-A explosive, but the build up of the detonation pressure is aot so marked .The detonation pressure for explosive 10 mm in tkicksress is 31. 55 GPa. When the thickness is incresed to 45 mm，the build up of d^tcmation pressure is not obvious within the measurement precision range, the pressure reached merely 35.54 GPa and the velocity of detonation wave is 8.68 km/s. The detonation pressure does not vary appreciably under the plane wave lens initiation system or the plane wave lens, PMMA attenuator of 10 mm thickness.

Based on experimental data, reactivity and temperature at various points of time in the TNT detonation reaction zone and Taylor zone are calculated. The nucleation and the growth of diamond from free carbon as is formed in the TNT detonation reactive zone have been estimated by classical homogeneous crystal nucleation and growth theory. The estimated yield of ultrafine diamond is in agree?ment with that from the experimental data.

An experimental system is established to observe and analyze the micro-detonation arc machining（MDAM） process. By means of high speed photography and current signal acquisition, the relationship between the external shape of micro-detonation arc and the working current is studied. The formations of ablation pit in Si₃N₄ and Al₂O₃ are observed by using high speed photography and the surface and cross-section topography are observed by using scanning electron microscape (SEM). The experimental results show that the diameter of micro-detonation arc increases with the working current and the diameter of ablation pit expands with the machining time; Si₃N₄ ceramic can decompose in machining, the surface structure is loosen, and some transverse cracks at subsurface are produced by thermal shock; Al₂O₃ ceramic can directly melt in machining, lots of micro-cracks distribute on the surface, and the main composition of deteriorative layer in grass phase.

By using electric probe array with different lengths each other, just in the shape of hedgepig, the free surface （inner surface) velocity history of cylindrical metal tube was measured which was driven by sliding inward detonation. The relation of free surface velocity v and radius of metal tube R was obtained elementarily, and some discussions were also given. The analysis elemen?tarily reveals the influence of explosive thickness on free surface velocity, and the detonation pressure increasing phenomenon under thicker nitromethane (40 mm) condition may be the cause of Digger ini-tial free surface velocity v0 than computed value based on C-J detonation theory. The result above lays a good foundation for further quantitative measurement of the free surface velocity of axial symmetric structure under inward detonation.

Twenty-one nitrotriazole compounds and its derivatives were calculated by density functional theory. Their optimized geometries and electronic structures were computed at the B3LYP/6-31+G (d, p) level. The optimized geometries of these compounds show that they have no imaginary frequencies, and they are stable on the potential energy surface. The heat capacity and enthalpy of some representative compounds at different temperatures were obtained by statistic thermodynamics. In order to calculate the standard enthalpies of formation for the derivatives of nitrotriazole, the isodesmic reactions were designed. The average molar volume and theoretical density were estimated using the Monte-Carlo method based on 0.001 e·bohr^-3 density space. Furthermore, the detonation velocity and pressure of the derivatives were estimated using the Kamlet-Jacbos equation. The results show that the ring of triazole has some aromaticity and the detonation velocities of these compounds are between 7.08 and 9.53 km/s. Detonation performance shows that these compounds are very good candidates for energetic material.

By means of an explicit nonlinear dynamic finite element computer code Ls-dyna, the spalla?tion in a cylindrical steel tube loaded by sliding-implosion was studied, and with a Tuler-Buctcher dam?age model, the physical process of spallation was reproduced. The simulation results show that I) the refraction angle of shock wave increases with the increase of propagative distance at the interface of ex?plosive and the cylindrical steel tube; 2) the oscillations of inner free surface velocity become weaker, but the periods get longer due to the interaction between the oblique incident wave and the reflection wave; 3) a critical value exists in the thickness of explosive leading to the spallation inside the cylindri?cal steel tube, and the initial spall thickness increases with the increase of the explosive thickness.

The flame propagation characteristics of the center core igniter with Iow- velocity-detonation tube (LVD tube) and that of the typical center core igniter have been compared by numerical simulation and experiments. The results demostrate that the LVD center core igniter has good igniting ability along the axis of the igniter.

The composite structure composed of SiC ceramic board and ultra-high molecular weight polyethylene (UHMWPE) fiberboard is studied. In order to understand the influence of component thickness on the penetration resistance of the anti-ballistic body， the test of 12.7 mm armor-piercing incendiary projectile penetrating into the composite structure was made to obtain the penetration effect at different impact velocities. A finite element model of a projectile penetrating into the composite structure is established， and the reliability of the model is verified by tests. The proposed finite element model is used to simulate the composite structure of 12.7 mm armor piercing incendiary projectile penetrating into different thickness components， and the failure mechanism and anti-ballistic performance of composite structure subjected to projectile penetration are analyzed. The results show that the proposed finite element model can be used to reliably calculate the effect of 12.7 mm armor piercing incendiary projectile penetrating into the composite structure. The ballistic performance of the composite structure increases linearly with the increase in the component thickness， and the influence of SiC ceramics on the ballistic performance is greater than that of UHMWPE fiberboard. With the increase in the thickness ratio of SiC ceramic and UHMWPE fiberboard， the ballistic performance of composite structure first increases and then decreases. When the thickness ratio is between 0.2 and 0.4， the ballistic performance of composite structure is the best.