Abstract:In order to determine the composition and content of eluent wastewater from the production of nitroglycerin/1，2，4-butanetriol trinitrate （NG/BTTN） mixed nitrate， a high performance liquid chromatographic （HPLC） gradient elution method was carried out to detect washing wastewater. The chromatographic conditions were determined as follows： the stationary phase was C18 （250 mm×4.6 mm， 5 μm） column， the mobile phase was acetonitrile/water solution， and and the detection wavelength was 200 nm. The results showed that six organic compounds were detected in the scrubber wastewater. By fitting the retention time of the compounds and their linear relationship with the partition coefficient LogD （27 samples were taken within 7 days）， it was determined that in addition to NG and BTTN， the following compounds were present in the scrubber wastewater from the production of mixed NG/BTTN nitrates： 1，2-dinitroglycerol（30.58%-41.20%）， 1，3-dinitroglycerol（110.69%-135.14%）， 1，2，4-butanetriol-1，2-dinitrate（7.90%-10.63%）， and 1，2，4-butanetriol-1，4-dinitrate（22.55%-27.95%）， with the standard deviations lower than 10%， and the method was sampled for 40 times within 10 d. It was proved that the method is accurate， reliable and applicable， and meets the testing needs of industrial production.

Abstract:A new type of cannon barrel with spiral grooves structure has been designed based on the principle of gas-curtain launching to reduce the launch resistance of underwater cannons. The low-resistance and high-speed launch of underwater cannons was achieved by the four spiral grooves opened on the inner wall of the barrel. A transient three-dimensional two-phase flow model of the gas-curtain launching and drainage process of underwater cannons was established， and the rationality of the model was verified. Based on this， numerical simulations of the drainage process of the spiral grooves structure were conducted， and the effects of straight grooves and spiral grooves on the gas-curtain drainage were compared and analyzed. The results show that during the initial expansion stage， the four gas jets rotate circumferentially and rapidly expand radially along the spiral grooves structure. Then， the jets interfere with each other and gradually converge， forming a columnar gas-curtain and starting· the cooperative drainage. During the formation of the gas-curtain， the spiral groove structure has a complex effect on the expansion velocity of the jet head， presenting an initial sharp decrease and subsequent decline with fluctuations. After the formation of the columnar gas-curtain， the velocity of the gas-curtain head increases nonlinearly. When the gas-curtain head expands to the outlet， the gas content of the spiral groove barrel increases by 9.3% compared to the straight groove barrel. Especially， the gas content reaches 100% within the range of 400 mm in front of the projectile.

Abstract:In order to characterize the mechanical response of double-base propellant， the viscoelastic properties and constitutive model of double base propellant were studied. Firstly， the viscoelastic properties of double-base propellant were investigated by tensile， compression and stress relaxation experiments with an observation of fracture surface. Then， a hyperelastic-viscoelastic model of double base propellant was established based on the Reduced Polynomial（N=5） model and Prony series. The parameters of the developed model were obtained by the experimental data. Finally， the hyperelastic-viscoelastic model of double base propellant was verified. The relatively error between the results of the simulation calculated by the hyperelastic model and the experiment for uniaxial tensile stress-strain is less than 5.01%. The relatively error between the results of simulation and experiment for stress relaxation is less than 6.49%. The developed hyperelastic-viscoelastic constitutive model of double-base propellant can well describe the mechanical properties of double base propellant， which provides a significant method for the research of mechanical properties of propellant.

Abstract:In response to the serious problems involving large smoke， flame and pungent smell known for a small and medium caliber weapon， the single base seven holes propellants were treated by chemical denitration method to prepare nitro gradiently distributed propellants with different denitration degrees. Their physicochemical， static burning properties， interior ballistic performance and emission hazard phenomenon were investigated. Based on the minimum free energy method， the influence of amount of camphor agent and the denitration degree on the combustion gases （CO， H₂） produced and unoxidized carbon were studied. The results show that with the increase of denitration degree， the explosion heat of propellants decreases from 4001 J·g^-1 to 3517 J·g^-1， the web thickness reduces from 0.92 mm to 0.89 mm， the content of stabilizer declines from 2.60% to 1.95%， the stability remains unchanged， B_m value increases to 0.66， and the progressive burning property enhances gradually； the better progressive burning of propellants， the higher initial velocity of the projectile under the same bore pressure condition was observed， the numerical expression and control method of ballistic performance for this investigated propellant were obtained based on the enantiomorphic coupling relationship established between the mass of charge， bore pressure and initial velocity； in comparison with the camphor-deterred propellants， the nitro gradiently distributed propellants demonstrated the promising characteristics of lower concentration of combustible gas， and less unoxidized carbon； in addition， the small flame， less irritating odour and low emission harmful phenomena are found for nitro gradiently distributed propellants during the firing test.

Abstract:In order to investigate the combustion stability of flake variable burning rate propellant under high and low temperature cycle preservation， based on the morphology of samples and the change of combustion performance， a 20 time thermal cycling treatment was carried out， in which samples were separately stored at 70 ℃ and -50 ℃ for 10 h as one cycle. The surface and section morphology of propellant was observed via optical microscope， and the combustion performance at 50 ℃， 20 ℃， -40 ℃ was tested by closed bomb. Microscopic observation shows that after thermal cycling treatment， the bubbles on the surface increase and the section of propellant becomes lumpy and uneven due to plastic deformation， while the interface between the inner and outer layers remains tight without visible cracks. The combustion performance basically unchanged after thermal cycling treatment， and the dynamic activity curves nearly overlap， for which the maximum ΔL_a is 2.57% at low temperature. After thermal cycling treatment， the temperature coefficient under high-pressure from normal to low temperature is significantly lower than that of the original under the same conditions， and the difference in pressure index of the flake variable burning rate propellant at high temperature and low temperature is smaller than that of the original under the same conditions. Attributed to bound interface and combustion consistency， flake variable burning rate propellant has good storage stability under different temperatures.

Abstract:The flame radiation characteristics of the single-base propellant and double-base propellant during combustion were explored for the guidance in the design of detectors for explosion suppression systems， by which the propellant flame spectroscopy experimental system was designed and constructed. The flame radiation spectra of typical single-base propellant and double-base propellant burning in air under different pressure conditions （-0.05， 0.00， 0.20 MPa） were collected and analyzed. Under atmospheric air， single-base propellant displays a weak continuous radiation only in the range of 550-650 nm. Due to the less interference of the continuous spectrum， the emission peaks of OH*， C₂*， CHO* and other emitting species can be identified in the combustion flame spectrum for the single-base propellant， and these active intermediates may be present in the flame zone during combustion. In contrast， the combustion flame radiation spectrum of double-base propellant shows the strong continuous radiation in the range of 200-1700 nm， which is attributed to that there are a large number of solid particles in its flame zone， that masks part of the emission peak information in the 200-1700 nm band. In the 1000-1700 nm band， the emission peaks of CN*， OH* and other groups were collected during the combustion of the double-base propellant. In addition， there are strong Na， K and Ca emission peaks in the flame spectra of the double-base propellant and single-base propellant， and Na， K and Ca species may come from the residual lignin in nitrocellulose. As the ambient pressure in the combustion chamber increases， the intensity of combustion radiation of both propellants is enhanced. The continuous radiation of double-base propellant in the initial stage of combustion is weak under low pressure conditions， and the characteristic peaks are similar to that of single-base propellant are collected. According to the test results， the detector for the single-base propellant should be designed based on the emission peaks of Na and K， while the detector for the double-base propellant should be designed in accordance to the peak wavelength of the continuous spectrum. The higher the ambient pressure， the lower the detector trigger threshold.

Abstract:The launching device of 105 mm short tube gun was designed to carry out the armor piercing projectile test under dynamic shooting condition. Transient pressure measurement system and high-speed camera were used in the experiment to obtain the chamber pressure and projectile motion parameters during the engraving process. The engraving resistance characteristic curves of projectile were calculated by projectile dynamics equation. Besides， the influence of different pressure rise rate on the process of projectile engraving was analyzed under two conditions. Based on the test conditions， the engraving deformation process of nylon belt of armor piercing projectile was numerically simulated by using the C-S model with elastic-plastic large deformation of belt material. The experimental data indicated that the engraving resistance increases first and then decreases with the engraving displacement in the engraving process. Therefore， when the engraving resistance reaches the maximum， only part of the nylon belt was completely squeezed. The elasticity of the nylon elastic band increases the contact area with the groove. When the average pressure rise rate of projectile bottom increases from 2.92 MPa·ms^-1 to 3.28 MPa·ms^-1， the engraving time shortens by 4.36% and the maximum engraving resistance increases by 5.12%. The nylon belt cross deformation stress cloud diagram was obtained by the numerical calculation to show that the elastic-plastic deformation of the nylon belt occurred. The interior of the elastic belt is mainly in the state of compression shearing and the main failure form of the elastic belt is tensile shearing failure. The displacement curves obtained by simulation and experiment have the same trend and the error is 5.24%.

Abstract:In order to explore the processing parameters for the continuous production of double-based spherical propellants with particle sizes in the range of hundred microns， a Co-axial flowing microfluidic installation was used to process the dispersed phase of a 10 % double-based propellant solution and prepare the double-based spherical propellants with a controllable particle size in the range of 400-700 μm. The effects of two-phase flow ratio（Q_c/Q_d） and chip size on the morphology and particle size of double-based spherical propellants were investigated. Moreover， the morphology， particle size distribution， and constant volume combustion performance of samples were characterized using scanning electron microscopy， optical microscope， and closed bomb test，respectively. Results show that， the median particle size （D₅₀） of the samples prepared into the same type of chip increases first and then decreases with the decrease of two-phase flow ratio. As the internal diameter of the continuous phase or the dispersed phase channel increases， the D₅₀ of the samples obtained at the same two-phase flow ratio increases successively. When the internal diameter of the continuous phase and the dispersed phase channels are 2 and 0.85 mm， and the two-phase flow ratio is 200.00， the resultant sample displays high monodispersity， smooth surfaces， dense inside， regular spherical shapes （average sphericity φ_K=0.949） and narrow size distribution （span=0.09）. Its D₅₀ is 539.94 μm， and the average particle density is 1.601 g·cm^-3. In the closed bomb test， the pressure-time curve shows that the samples with two varied packing densities （Δ₁=0.12 g·cm^-3， Δ₂=0.20 g·cm^-3） can burn stably， and the dynamic vivacity-relative pressure curve follows the regressive burning law of the dense spherical propellants.

Abstract:The research on low-sensitivity gun propellants has a vital impact on the survivability and safety performance of weapon system. Gun propellant （IM） with nitrocellulose （NC） and glycidyl azide polymer （GAP） as binder was prepared. N-butyl-N- nitramine （Bu-NENA） was used as low sensitive energetic plasticizer， hexogen （RDX） was used as high-energy filler and graphite as additive of thermal conductive. The physicochemical， combustion， mechanical， and sensitivity properties of the IM gun propellant were studied， and the insensitivity properties were further studied by slow cook-off， fast cook-off， bullet impact， fragment impact and sympathetic detonation tests. Results showed that the gun propellant had stable combustion performance， and the impetus was1050 kJ·kg^-1. Theoretical explosion temperature was 2677 K. The impact strength and the compressive strength were 8.2 kJ·m^-2 and 131.5 MPa at -40 ℃， respectively. The sensitivity of the gun propellant （H₅₀=62.62 cm，P=28%，V₅₀=1.95 kV） was greatly reduced compared with TEGN gun propellants（H₅₀=16.33 cm，P=100%，V₅₀=2.02 kV）. Moreover， only combustion reactions were observed in slow cook-off， fast cook-off， bullet impact， fragment impact and sympathetic detonation tests. It demonstrated that the prepared gun propellants possessed good low vulnerability characteristics.

Abstract:In order to obtain the gun propellant with progressive combustion characteristics and corresponding control methods at multi-dimensions， according to the principle of internal ballistics， the concept of the pre-grooved gun propellant was proposed. The physical and mathematical models of the combustion process were established， and the Г-Ψ relationship was deduced. The principle of progressive combustion and multi-dimensional control methods were demonstrated. The method used for the preparation of the pre-grooved gun propellant was described. The pre-grooved gun propellant structured with a center opening was designed， and propellants having different groove numbers and various length/outside diameter ratios were prepared. In order to compare with the seven-hole propellants with and without coating ， the combustion performance of the pre-grooved gun propellant was characterized by the closed bomb test. The experimental results show that the pre-grooved gun propellant has the progressive combustion behavior as theoretically designed. Compared with the seven-hole propellant， the combustion enhancement value（ΔL） value obtained by using this method is increased by 2 folds， the progressive combustion characteristic（L_m/L₀） value is increased by 24.4%， and the relative pressure at the split point（B_m） value is increased by 32.4%. The progressive combustion feature exhibited by pre-grooved gun propellants outperforms that of the seven-hole propellant， and was comparable to that of the coated seven-hole propellant.

Abstract:In order to evaluate the output energy characteristics of the ignition cap， it was proposed to conduct the ignition cap firing test in an open burster container and use a high-speed mid-wave infrared thermal imager to capture the whole process of the ignition cap firing. Since it was difficult to measure the output flame temperature of ignition cap， the drop weight instrument was used to give the corresponding initial firing energy of ignition cap. At the same time， the infrared thermal imager was triggered to collect flame information. The experimental data and infrared images of ignition cap under three test conditions of normal（25 ℃）， heated（50 ℃） and frozen（-49 ℃） temperature were processed. The results show that the output flame maximum temperature can reach up to 1204 ℃， and the flame duration is about 3-4 ms. The whole process of the flame with time can be divided into four stages： firing， diffusion， forming and dissipation， and the temperature in the top and bottom area of flame is much higher than in other areas. Through calculation and software correction， the measurement error of this test is below 6.6%， which can prove the reliability of the method and provide a new way for evaluating the output energy characteristics of ignition cap.

Abstract:In order to prepare gun propellants with complex geometries， the extrusion 3D printing process of double base gun propellants was proposed. Square-shaped， wheel-shaped， star hole-shaped and lace seven hole double base gun propellants were printed by screw extrusion gun propellants 3D printer. The surface structure， size uniformity， density and mechanical property of the printed gun propellants were characterized. The results show that the surface of the printed gun propellants is smooth without obvious defects. The size uniformity of lace seven hole gun propellants reaches the standard of traditional gun propellant preparation process， and the size uniformity of arc thickness for wheel-shaped gun propellant is good， with a standard deviation of 0.026 mm and a relative standard deviation of 0.92%. The density of square-shaped gun propellant is higher （1.567 g·cm^-3） than those of other gun propellants （1.549-1.559 g·cm^-3）. The tensile strength of gun propellant samples with concentric filling path （the filling line direction is parallel to the tensile direction） and straight line （the filling line direction is perpendicular to the tensile direction） are 14.467 MPa and 10.789 MPa， respectively， the former is equivalent to that of gun propellants prepared by traditional extrusion process. The good printing of multi geometry gun propellants with radians and angles provides a basis for the preparation of complex geometry gun propellants.

Abstract:In order to solve the dilemma of traditional technology to prepare gun propellants with complex structure and explore a new way to improve incremental combustion surface of gun propellants， 3D direct ink-writing was used to design and print nitrocellulose-based gun propellants embedded with multi-cubic pores. The 3D printed nitrocellulose-based gun propellants embedded with multi-cubic pores were characterized by constant volume combustion and internal ballistic properties. The results show that the printed nitrocellulose-based gun propellants embedded with multi-cubic pores， prepared by nitrocellulose， energetic plasticizer， and solvent as printing materials， are in accordance with the expected design of incremental combustion surface. Due to the influence of the diameter of printing needle， the ratio of dissolved cotton， the ratio of alcohol/acetone， and the speed of solvent volatilization， there is a certain deviation between design size and actual size of printed gun propellants. The preliminary ballistic test of 12.7 mm machine gun shows that when the mixed charge of NC-120 and D-4/7 is 16 g and the charge ratio is 1∶1， the bore pressure is 314.2 MPa and the muzzle velocity is 854.1 m·s^-1. The stable and normal combustion of the direct ink-writing printed gun propellants embedded with multi-cubic pores in the chamber is realized. However， for the sake of practical application of printed gun propellants embedded with multi-cubic pores， several parameters need to be further optimized such as shape， web size， and the web size matching between inner and outer layer.

Abstract:In order to explore the characteristics of ignition and flame-propagation process of the modular charge， a small metal modular cartridge was designed and the ignition test was carried out. On this basis， the internal ballistic two-dimensional gas-solid two-phase flow model of the test was established， the model was solved by using CE/SE method. The variation characteristics of flow field parameters in the chamber are obtained， and the numerical results are in good agreement with the experimental results. The numerical results reveal the changing process of the pressure distribution of the ignition tube and main charge area during the flame-propagation process， the flow law of the gas phase and the influence of its radial propagation effect on the combustion of the propellant in main charge area； The rupture of the cartridge’s end cap will lead to the formation of a shock wave in free space of the chamber， the reason for the formation of the shock wave are discussed. In addition， the numerical simulation of the gas jet of the vent hole breaking-progress under the hypothetical working condition is carried out， the gas phase flow law and the pressure-boosting law of the main charge area are studied. The comprehensive results show that under the condition of modular charge， the radial effect of the gas phase in the ignition tube is obvious during the entire ignition and flame-propagation process， and the particularity of the charge structure can easily lead to the formation of shock waves.

Abstract:To alleviate the aggregates of n-Al particles and improve its combustion performance， high-energy low-sensitivity nitrochitosan （NCh） with a honeycomb network structure was used as coating agent to prepare a binary nanocomposite with uniform structure through an acoustic resonance method. The morphology， structure and combustion performance of NCh/n-Al were investigated by XRD， SEM， TEM and laser ignition， and compared with that of NC/n-Al composite. The results show that the prepared NCh/n-Al has uniform morphology and good dispersion. Compared with pure n-Al and NC/n-Al， the ignition delay time of NCh/n-Al is shortened by 6 ms and 20 ms， respectively. The combustion of NCh/n-Al is more complete， the condensed combustion products are mainly Al₂O₃， a very small amount of unburned Al and carbon residue， and the particle size is significantly smaller.

Abstract:Mechanically mixed and electrostatic sprayed RDX/NC/AP/Al composite explosive using nitrocellulost （NC） as binder， ammonium perchlorate （AP） as oxidant， cyclotrimethyltrnitramine （RDX） and nano aluminum powder （Al） as combustion agent were prepared based on zero oxygen balance. The morphology， structure， thermal properties， combustion process and mechanical sensitivity of the different samples were analyzed by the scanning electron microscopy （SEM）， the Fourier transform infrared spectroscopy（FT-IR）， thermogravimetric differential scanning calorimeter （TG-DSC）， mechanical sensitivity and high-speed photography. The component（NC， RDX， AP and Al） in RDX/NC/AP/Al composite explosives obtained by both method are physical composite. However， the microstructure of mechanically mixed RDX/NC/AP/Al demonstrated in spheres and the electrostatic sprayed samples are microspheres. The mass loss process of RDX/NC/AP/Al composite explosive obtained by two methods contained two stages （200-210 ℃ and 250-350 ℃）. The first stage is the decomposition of part of RDX and AP， while the second stage is the decomposition of the remaining RDX and NC. Compared with the mechanical mixed samples， the activation energy and the critical temperature of thermal explosion of electrostatic sprayed RDX/NC/AP/Al increased by 41.25 kJ·mol^-1 and 4.09 K， respectively. Besides， the mechanical sensitivity is reduced， and the combustion rate is also improved.

Abstract:To investigate the influence of the loading density of main propellant charge on the propagation characteristics of ignition charge gas in the granular propellant bed， the test platform for ignition and propagation of a large-diameter dense propellant bed was established， and the flame sequence diagram and the pressure changes of partial pressure gauges were recorded in tests. The porous medium model was used to simulate the granular propellant bed in the charge chamber， and the ignition and propagation model corresponding to the test device was established to numerically simulate the flow process of ignition charge gas in the granular propellant bed. The simulation results were compared with the test results to verify the reliability of the model， and then the propagation characteristics of temperature and pressure fields of gas in the propellant bed with different loading densities were calculated. The results show that the calculated results are in good agreement with the experimental flame propagation sequence process and the experimental pressure histories， which verifies the reliability of the model. Under the condition of any porosity， the axial displacement of flame front develops rapidly and the axial velocity decreases from 25-30 m·s^-1 to 10 m·s^-1 during 0-10 ms， ， and the axial velocity decreases to 2-3 m·s^-1 during 10-40 ms. Similarly， under the condition of any porosity， the development of radial displacement of flame front is concentrated during 2.2-3 ms， and the radial velocity decreases to 20-22 m·s^-1 at 3 ms. However， the radial velocity at the initial time is large for large porosity. When the porosity increases from 0.3 to 0.5， the pressure difference at different positions in the chamber decreases 16.7% from 0.24 MPa to 0.20 MPa， and the uniformity and instantaneity of ignition are improved. With the increase of porosity， the axial and radial resistances of the flame front in propagation process decrease， the axial expansion displacement of the flame front and the initial velocity of flame propagation in the axial and radial directions increase， but the final velocity tends to be the same. The smaller the pressure in the chamber， the smaller the pressure difference in the chamber.

Abstract:The pyrotechnic formulation， that emitting purple light by using the synergetic effect of multi flame colorants， was designed and optimized theoretically. Based on the principle of additive color mixing， one purple-light-emitting pyrotechnic formulation containing flame colorants that generating red and blue colors was proposed. The types and contents of different colored light emitters were determined by REAL program. The color coordinates， wavelengths， color purities and chromaticity diagrams of different formulations were calculated by MATLAB program， and then the optimized pyrotechnic composition with purple light was determined. The theoretical results showed that the optimal formulation of purple-light-emitting pyrotechnics was Sr（NO₃）₂/2CuCO₃·Cu（OH）₂/Al/C₆H_9.6O_1.6 with the ratio of 48/32/12/8. The oxygen balance of the formulation was -0.11 g·g^-1 and the colored light emitters were Sr， SrO， SrOH， CuO， CuOH， and CuH， respectively. The purple chromaticity coordinate point was （0.2449，0.1497）. The virtual dominant wavelength of purple light was 446 nm， and the color purity was 0.40. The experimental measurements of the above formulation showed that the chromaticity coordinate point was （0.2425，0.1588）， the virtual dominant wavelength of purple light was 439 nm， and the color purity was 0.44. The purple light was actually produced by the mixing of red light （766 nm） and blue light （418 nm）， with good purple effect. The simulation results are in good agreement with the experimental results. This design method can provide a theoretical basis for the formulation optimization of other colored-light-emitting pyrotechnic compositions with multi flame colorants and the study of related problems.

Abstract:In order to extract the effect characteristic parameters （smoke screen width， smoke screen height， smoke screen coverage area， masking time） and motion characteristic parameters （vertical and horizontal diffusion speed） from measured infrared smoke screens and， the layout of the test site for field measurement of infrared smoke screens was designed. The infrared thermal imager was used to collect the video data of the explosion and diffusion process of the infrared smoke bomb in 112 secs， and the five-frame difference method was used to segment and extract the infrared smoke screen from the video sequence of the infrared thermal imager， then the effect characteristic parameter area and motion characteristic parameter area of the infrared smoke screen were obtained. According to the geometric relationship of the site layout， the test results have been corrected for wind direction. The pixel points of the infrared smoke screen image were used as the basic unit that the actual smoke screen height and width values represented by each pixel in each frame of the video sequence were solved， and then the effect characteristic parameters and motion characteristic parameters of the infrared smoke screen were obtained. It was verified by the analysis of actually measured infrared smoke screen videos that this method can quickly extract the characteristic parameters of infrared smoke screen. At the moment of explosion， the width， height， and area of the smoke screen rapidly increase to 4.7 m， 5.2 m， and 24.2 m²， respectively， and the front diffusion speeds along the wind direction reached 126 m∙s^-1 horizontally and 146.3 m∙s^-1 vertically.， It has highly practical application value for the research on infrared smoke screens， including the correction of diffusion simulation equation， the combat effectiveness evaluation， and on the combat operation.

Abstract:In this work， the auto-ignition behaviors of FOX-7/NC/NG powder were investigated by using rapid compression machine （RCM） under a high temperature environment. High speed images and pressure evolutions were used to record the responses of FOX-7/NC/NG samples under high temperature and pressure conditions. Results show that the samples were not able to ignite at 3.0 MPa and 598.1 K， with the heating rate of about 1.2×10⁴ K·s^-1. With the temperature increasing to 913.1 K （the heating rate is about 2.5×10⁴ K·s^-1）， the auto-ignition was observed. In addition， the validated tests of FOX-7/NC/NG samples were conducted. Results show that the experiment has a good repeatability. The uncertainties of ignition delay times （IDT_I） and burning duration are less than 20% and 5%， respectively. Lastly， the auto-ignition behaviors of FOX-7/NC/NG samples were studied at different thermal loading rates. It was found that the higher thermal loading rate， the faster ignition and the shorter burning duration.

Abstract:In order to study the aging migration process and influencing factors of deterred DB propellants， a theoretical model on the deterrent distribution and the change of combustion performance caused by aging migration was established based on the normal distribution characteristics of deterrent and the inference of Fickian second diffusion law. Six kinds of propellants with different contents of nitroglycerin（NG） and dibutyl phthalate（DBP） were treated by accelerated aging experiments at different temperatures and times， and the combustion performances of propellants were tested by closed bomb vessel. The kinetic process and thermodynamic influence of aging migration for propellants were analyzed. Theoretical analysis shows that the integral value growth rate of the dynamic vivacity for deterred spherical propellants presents a good linear growth relationship with aging time. The results of the closed bomb vessel show that the percentage increase of the maximum dynamic activity for the six propellants after accelerated aging also gives a good linear relationship with aging time， which is consistent with the theoretical research results. The established thermodynamic equation of aging migration for deterred propellants is basically consistent with the experimental results， and the logarithm of migration driving factor and the reciprocal of temperature present an obvious linear negative correlation. When the total content of NG and DBP in propellants is greater than 15%， the migration driving factor is more susceptible to the influence of temperature， leading to migration invalidation. When the total content of NG and DBP is less than 15%， the invalidation rate caused by deterrent migration is relatively slow， which is more conducive to the use and shooting safety after the storage of propellants.

Abstract:The effects of four typical stabilizers （DPA， C2， AKⅡ， MNA） on the thermal decomposition behavior of nitrocellulose， the thermal decomposition parameters of nitrocellulose samples under different conditions are obtained by DTA， DSC and ARC. The results of non-isothermal calorimetry show that the critical temperature of thermal explosion of nitrocellulose increases by 0.06， 0.82， 1.00 and 1.56 K， respectively， after adding four typical stabilizers. The adiabatic thermal test show that the stabilizers have limited effect on the initial temperature rise rate and pressure of nitrocellulose at the initial stage， but reduces the maximum temperature rise rate of nitrocellulose by 0.39， 0.64， 0.70 and 0.65 K·min^-1. The effects of thermal history on the thermal decomposition of nitrocellulose samples are investigated by DSC interruption and re-scanning method. The results show that four typical stabilizers have good thermal stability. Although the initial thermal decomposition of nitrocellulose is less affected by stabilizers， but with the progress of thermal decomposition reaction， the severe autocatalytic decomposition caused by nitrocellulose thermal decomposition products could be alleviated by rapid reaction with stabilizers， and the influence of thermal history on the thermal decomposition of nitrocellulose could be reduced. N-methyl-4-nitroaniline has the most obvious inhibition effect on the autocatalytic decomposition of nitrocellulose.

Abstract:With extrusion deposition technology as the core， based on the features of high viscosity and no-resistant to high temperature for propellant， the extrusion deposition rapid prototyping system for propellant was designed and a complete prototype was built. Using a certain ZY propellant as raw material， different materials with concentrations of 27.3%， 33.3%， 38.5%， 42.9%， 46.7% and 50% were prepared. Through 3D printing extrusion experiments， it is found that there is a polynomial function relationship between the inner diameter of the needle and the material concentration. The filling speed range is 2-4 mm·s^-1， the filling rate range is 70%-90%， and the temperature range of the bottom plate is 25-45 ℃. On this basis， the propellant 3D printer was used to print the propellant， and the compression test was carried out. The results showed that the compression strength of the propellant could reach up to 230 MPa.

Abstract:In order to investigate the mechanical response process of porous propellant under impact loading and the effect of geometric parameter changes on the mechanical properties of the particles， ANSYS/LS-DYNA was used to establish the numerical models of seven-hole and nineteen-hole propellants to simulate the force of the particles under impact loading. Then， the models of single-hole propellant， seven-hole and nineteen-hole propellants with aspect ratios of 1∶1 and 2∶1， and lace-shaped seven-hole and nineteen-hole propellants were established to study the influence of the number of holes， aspect ratios and shape on propellant stress. The results show that the particles rebound after being compressed， the stress on the surface in contact with the drop hammer increased gradually from the center to the boundary， and the middle of the particles expanded. The increase of the number of holes will change the continuity of the stress distribution on the end surface due to the stress concentration at the hole. Compared with the single-hole propellant， the duration under stress and the maximum compressive displacement of the seven-hole propellant are increased by 3.39% and 3.76%， respectively， whereas the duration under stress and the maximum compressive displacement of the nineteen-hole propellant are increased by 10.17% and 15.05%， respectively. When the number of holes remains constant and the aspect ratio increases from 1∶1 to 2∶1， the peak stress decreases and the peak compressive displacement increases. The lace-shaped particles were more prone to cause stress concentration in the concave of lace than the cylindrical ones. The study of the stress response process of the propellant and its influencing factors provides fundamental data to study the mechanical properties of the propellant.

Abstract:The accommodation of liquid propellant in current-used weapons and equipment makes it important for expanding its application field in various existing weapon systems in the form of general solid propellant. In the current paper， a nitrocellulose-based energetic hollow spherical shell that can be used to encapsulate the liquid propellant is designed. The preparation method is based on the spherical propellant prepared by the internal solution method and on the principle of double emulsification， using W/O type Pickering emulsifier active calcium phosphate and O/W type emulsifier sodium carboxymethyl cellulose to make the emulsion containing nitrocellulose emulsify into a monodisperse W/O/W type emulsion， then evaporate the solvent to obtain the shell. The feasibility of activated calcium phosphate on the W/O type emulsifier has been examined through triple contact angle technique using a contact angle meter. Besides， the basic morphology and particle size， as well as packing density have been characterized using a ultra-depth-of-field electron microscopy system and mass-volume method， respectively. Results show that the three-phase contact angle of activated calcium phosphate is 121.80°. The shell has a large cavity structure with a particle size of 0.7-1.1 mm and a bulk density of 0.1-0.2 g·mL^-1. The microstructure demonstrated a majority of white fiber structure. In addition， embedded white particles in the fiber could also been observed. The optimized ratio of sodium carboxymethyl cellulose to active calcium phosphate， and active calcium phosphate to nitrocellulose should be 1∶1-1.25∶1 and 0.16∶1-0.24∶1， respectively.