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Effects ofmodulenumberand firing conditiononchargethermal safetyingunchamber

Defence Technology（防务技术） 2022年第1期18卷 27-37页

作者： Huan-yu Qian yong-gang yu Jing Liu School of Energy and Power Engineering Nanjing University of Science and Technology Narjing 21094 China Acudemny of Opto-Electroric China Electronis Technology Group Corporation(AOE CETC)Tianjin300308China

Thermal safety of modular charge which is fed into and retained in the chamber after gun fires consecutively is first investigated with cook-off method,A two-dimensional cook-off model of modular charge in gun chamber is established and the cook-off process of modular charge in gun chamber is numerically *** the effects of module number and firing condition on charge thermal safety are evaluated by researching the cook-off response characteristics of *** results show that under conditions of different module numbers the cook-off responses all occur on the module closest to the boundary of missile,and the single-base propellants located at the inner surface of cartridge ignite *** the number of loaded module changes from 1 to 6,the cook-off response temperatures vary little,only in a small range of 478.1 K-482.4 *** cook-off response times decrease logarithmically in the range of 211.25-166.7 s with the increasing length of residual air gap in gun *** simulation results are well matched with the experimental ***,different firing conditions have greatinfluence on the cook-off response time,minor influence on the initial response position and little in-fluence on the response *** the three conditions of consecutive 32 launches with 5 rounds/min,43 launches with 1 round/min,and 41 launches with different firing frequencies,the cook off response temperatures are 479.2 K,481.1 K and 479.9 K respectively and the response times are 709.25,211.2 s and 214.4 s *** response position is near the middle area of the inner cartridge surface in the former condition and near the right area in the latter two conditions.

关键词： Thermal safety Modular charge Cook-off Firing condition

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Numerical simulation of cook-off characteristics for AP/HTPB

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Defence Technology（防务技术） 2018年第5期14卷 451-456页

作者： Qing Ye yong-gang yu School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing210094China

The present study is devoted to researching the thermal security problems of large-scale solid rocket motor with Ammonium perchlorate/Hydroxyl-terminated polybutadiene(AP/HTPB). A two-dimensional axisymmetric model for the cook-off of solid rocket motor is established. The reaction kinetics for the cook-off process of AP/HTPB is described by the two-step global chemical mechanism. Numerical predictions of the cook-off behavior for the propellant are conducted at fast heating rate of 1.45-2.45 K/s,and slow heating rate of 0.001-0.003 K/s, respectively. The results show that in the fast cook-off condition. the initial ignition position of AP/HTPB occurs in the annular region of the outer wall of propellant without exception, and the center point in the region is(889.1,149.5). For the region, the axial width is1.8 mm and radial thickness is 0.8 mm. However, in the slow cook-off condition, the ignition center position is shifted along the axial direction toward the right end face of the propellant with the increase of heating rate. Therefore, the influence of heating rate on ignition temperature and ignition delay time is nonnegligible within a certain range.

关键词： Cook-off Numerical simulation AP/HTPB

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Numerical simulation and optimized design of cased telescoped ammunition interior ballistic

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Defence Technology（防务技术） 2018年第2期14卷 119-125页

作者： Jia-gang Wang yong-gang yu Liang-liang Zhou Rui Ye School of Energy and Power Engineering Nanjing University of Science and Technology Chongqing Wangjiang Industry Co. Ltd

In order to achieve the optimized design of a cased telescoped ammunition(CTA) interior ballistic design,a genetic algorithm was introduced into the optimal design of CTA interior ballistics with coupling the CTA interior ballistic model. Aiming at the interior ballistic characteristics of a CTA gun, the goal of CTA interior ballistic design is to obtain a projectile velocity as large as possible. The optimal design of CTA interior ballistic is carried out using a genetic algorithm by setting peak pressure, changing the chamber volume and gun powder charge density. A numerical simulation of interior ballistics based on a 35 mm CTA firing experimental scheme was conducted and then the genetic algorithm was used for numerical optimization. The projectile muzzle velocity of the optimized scheme is increased from 1168 m/s for the initial experimental scheme to 1182 m/s. Then four optimization schemes were obtained with several independent optimization processes. The schemes were compared with each other and the difference between these schemes is small. The peak pressure and muzzle velocity of these schemes are almost the same. The result shows that the genetic algorithm is effective in the optimal design of the CTA interior ballistics. This work will be lay the foundation for further CTA interior ballistic design.

关键词： Cased telescoped ammunition Interior ballistics Gunpowder Optimization genetic algorithm

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Numerical investigation of a muzzle multiphase flow field using two underwater launch methods

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Defence Technology（防务技术） 2022年第8期18卷 1454-1469页

作者： Jing-hui Zhang yong-gang yu Xin-wei Zhang School of Energy and Power Engineering Nanjing University of Science&TechnologyNanjing210094China

A two-dimensional axisymmetric model, employing a dynamic mesh and user-defined functions, is used to numerically simulate the transient multiphase flow field produced by an underwater gun. Furthermore, a visualized shooting experiment platform with a high-speed camera is built to observe the evolution process of such a multiphase flow field. The simulated phase distribution diagram is agreed well with the shadow photo of the experiment, indicating that the numerical model is reasonable. Further examinations of the multiphase flow fields by using the submerged and sealed launch methods show that use of the sealed launch can significantly improve the interior ballistic performance of an underwater gun. In the cases by using these two types of underwater launch methods, the displacement of the projectile within the range of the muzzle flow field meets the exponential law over time. Moreover, a not fully developed bottle-shaped shock wave is formed when t = 0.4 ms, but this bottle-shaped shock wave expands more rapidly for the sealed launch. In addition, the amplitude of pressure oscillation for the sealed launch is larger than that of the submerged launch, but the pressure oscillation of the sealed launch lasts shorter.

关键词： Underwater launch Multiphase flow Muzzle flow field Numerical simulation Mach disk

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Effects of Mg/PTFE pyrotechnic compositions on reignition characteristics of base bleed propellants and heating mechanism

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Defence Technology（防务技术） 2022年第1期18卷 94-108页

作者： Xiao-chun Xue Long-ze Ma yong-gang yu Schooi of Enerey and Power Engineering Nanjing Universiry of Science and Techmology Narine lianesu 210094 China BYD Compary Liruied ShenzheL Guanedong 518118 Chna

The effects of magnesium/polytetrafluoroethylene(Mg/PTFE)pyrotechnic compositions on the coupled flow field and reignition mechanism are important aspects governing the perfommance and range of base bleed projectiles(BBPs).Owing to a decrease in pressure and temperature when the BBP leaves the muzzle,rapid depressurization occurs,which extinguishes the base bleed *** Mg/PTFE py-rotechnic composition pressed in the igniter of the base bleed unit(BBU)provides additional energy to the BBU via a chemical ***,the extinguished base bleed propellant is reignited under the effect of high-temperature combustion gas jets from the *** this study,a numerical analysis is conducted to evaluate the effects of PTFE and Mg granularity as well as Mg/PTFE pyrotechnic *** to the rapid depressurization,the temperature and pressure was found to decrease fordifferent Mg/PIFE pyrotechnic ***,the depressurization time increased as the PTFE granularity increased,the Mg granularity decreased,and the Mg content *** the pressure in the combustion chamber of the BBU decreased to the atmospheric pressure,the combustion gas jets from the igniter expand upstream(rather than downstream).However,these combustion gas jets exhibit different axial and radial expansion characteristics depending on the pyrotechnic compositions used,The results show that the reignition delay time,ta,of the base bleed propellant was 377.608,94.27,387.243,523.966,and 221.094 ms for cases A-E,***,it was concluded that the Mg/PTFE pyrotechnic composition of case B was the most beneficial for the reignition of the base bleed propellant,with the earliest addition of energy and mass to the BBP.

关键词： Thermal effect High-temperature combustion gas Mg/PTFE pyrotechnic Compositions Reignition

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The influence of nozzle diameters on the interaction characteristic of combustion-gas jets and liquid

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Defence Technology（防务技术） 2017年第4期13卷 257-262页

作者： Xiao-chun Xue yong-gang yu Jin-ming Xie School of Energy and Power Engineering Nanjing University of Science and Technology Nanjing China Luzhou North Chemical Industry Corporation Luzhou China

To investigate the controlling method of interior ballistic stability of bulk-loaded propellant guns,the combustion-gas generator and cylindrical stepped-wall chamber are designed aiming at the injection processes of combustion-gases in *** expansion courses of Taylor cavities and the turbulent mixing characteristic of gaseliquid are recorded by means of high speed photographic *** on the experiment,three-dimensional unsteady model on the interaction of gas and liquid is established to simulate expansion characteristics of twin combustion-gas jets in liquid under different nozzle *** distribution regularities of characteristic parameter in jet field are obtained and *** results show the pressure,velocity and temperature distributions under different nozzle diameters are basically the same at the initial *** time goes on,these characteristic parameters under different nozzle diameters have large differences.

关键词： Fluid mechanics Combustion-gases Taylor cavities Jet shape Bulk-loaded propellant

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Softening of C-H Symmetric Stretching Vibrational Modes for CH2 and CH3 Radicals Adsorbed on Cun （n=1-6） Clusters

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Chinese Journal of Chemical Physics 2012年第6期25卷 649-653,I0003页

作者： Xi-hui Chenga Da-jun Ding yong-gang yu Ming-xing Jin School of Energy and Power Engineering Nanjing University of Science and Technolo~ Nanjing210094 China Institute of Atomic and Molecular Physics Jilin University ChanEchun 130012 China

The properties of C-H vibration softening for CH2 and CHa radicals absorbed on Cun（n=1-6） clusters have been investigated, using the density functional theory with hybrid functional. The results indicate that the absorption of CH2 on Cu clusters is stronger than the case of CH3. The vibrational frequencies of C-H bonding agree with the experimental results obtained for CH2 and CH3 absorbed on Cu（111）. With the increase of cluster size, the softening （Einstein shift） of C-H vibrational modes become stronger.

关键词： Radical CH2 Radical CH3 Cu cluster C-H vibrational mode softening(Einstein shift)

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Analysis of Micro-scale Flame Structure of AP/HTPB Base Bleed Propellant Combustion

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Defence Technology（防务技术） 2013年第4期9卷 217-223页

作者： Rui YE yong-gang yu yong-jie CAO School of Energy and Power Engineering Nanjing University of Science and Technology

A complex multiple flame structure is formed during the combustion of AP/HTPB base bleed *** AP monopropellant flame is concentrated in a thin zone above the burning surface of AP crystal to maintain self-sustained *** to the low temperature near the burning surface,the diffusion between the decomposition products of AP and the pyrolysis products of HTPB occurs,and a partly pre-mixed diffusion flame structure-leading edge flame(LEF)is *** effects of pressure,chemical reaction rate and AP particle size on diffusion flame structure in the range from 20 atm to 100 atm are *** Peclet number increases from 6.64 at 20 atm to 21.91 at 100 atm when AP particle size is 140 *** high temperature zone is blown away from the burning surface because the convective transport rate increases with the increase in Peclet *** chemical reaction rate is enhanced and the diffusion mixing is inhibited as Damkohler number *** chemical heat release is more concentrated and the chemical reaction zone becomes narrow when Damkohler number changes from 330 at20 atm to 4700 at 100 *** AP particle diameter is decreased to 60 mm,the diffusion time scale is reduced due to the reduced diffusion length *** the diffusion mixing is enhanced and a more pre-mixed flame is *** burning rate increases because the more pre-mixed heat release increases the heat feedback to the HTPB binder.

关键词：推进剂燃烧火焰结构 HTPB 结构分析 AP 底排化学反应速率 Peclet数

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Geometrical Structures and Electronic Properties of Copper-Doped Aluminum Clusters

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Chinese Journal of Chemical Physics 2012年第2期25卷 169-176,I0003页

作者： Xi-hui Cheng Da-jun Ding yong-gang yu Ming-xing Jin School of Energy and Power Engineering NanJing University Of Science and TechnologyNanjing 210094China Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China

Using density function theory （DFT）, the Cu-doped Aln （n=1-15） clusters have been stud- ied. The electron affinity, ionization potential, Mulliken population analysis of Cu, mean polarizability, polarizability anisotropy, dipole moments and HOMO-LUMO gaps have also been calculated on the basis of optimized geometries. The results indicate that there is magic numbers in copper-doped aluminum clusters and electronic characteristic depended on the size of clusters. As n=13, the electron affinity and ionization potential of cluster changed more than 0.3 and 0.6 eV respectively, compared with neighborhood clusters.

关键词： Density function theory electronic properties Cu doped A1 clusters

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Numerical simulation of base flow with hot base bleed for two jet models

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Defence Technology（防务技术） 2014年第3期10卷 279-284页

作者： Wen-jie yu yong-gang yu Bin NI School of Energy and Power Engineering Nanjing University of Science & Technology North Information Control Group Ltd

In order to improve the benefits of base bleed in base flow field,the base flow with hot base bleed for two jet models is *** axisymmetric Navier-Stokes equations are computed by using a finite volume *** base flow of a cylinder afterbody with base bleed is *** simulation results are validated with the experimental data,and the experimental results are well *** this basis,the base flow fields with base bleed for a circular jet model and an annulus jet model are investigated by selecting the injection temperature from 830 K to 2200 *** results show that the base pressure of the annular jet model is higher than that of the circular jet model with the changes of the injection parameter and the injection *** the circular jet model,the hot gases are concentrated in the vicinity of the *** the annular jet model,the bleed gases flow into the shear layer directly so that the hot gases are concentrated in the shear *** latter temperature distribution is better for the increase of base pressure.

关键词： Fluid mechanics Base bleed Base flow Numerical simulation Annulus jet

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