水下发射对机枪膛口温度场影响的数值分析
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摘要
为了解不同发射环境下机枪的膛口温度场分布特性,对12.7 mm机枪在空气和水中射击所形成的膛口温度场进行了数值模拟和对比分析。数值计算借助Fluent软件,并利用User Defined Function(UDF)和动网格技术。计算结果表明,机枪水下密封式发射时,弹丸出枪口就开始减速,火药燃气在弹后减速、聚集而温度升高,使得燃气初始喷射温度达到2653 K,比空气中发射时(2236 K)高417 K。受弹丸运动和气液界面的共同影响,在弹丸出膛70μs时形成马赫盘,而空气中发射时弹丸出膛200μs才初步形成马赫盘。与空气中发射相比,水下发射时形成的激波核心区较小,但核心区温度更高;其中压缩波中最高温度接近3200 K,比空气中发射时相应区域约高1500 K。通过拟合水下密封式发射时膛口形成的马赫盘位置随时间变化曲线,发现其位置与时间在弹丸出膛200μs内满足指数变化规律。
In order to understand the distribution characteristics of the muzzle temperature field for gun launched in different environments,numerical simulation and contrast analysis for 12.7 mm gun launched in air and underwater were carried out. W ith the FLUENT software, the numerical simulation was performed using User Defined Function(UDF) and dynamic grid technology. The numerical results show that when the gun is sealed and launched underwater, the velocity of projectile slows down just when it contacts water. At this time,the gunpowder gas after the projectile is slowed up and its temperature is raised,so that the initial injection temperature of the gas reaches 2653 K, which is 417 K higher than that in air(2236 K). Influenced by both the projectile movement and the gas-liquid interface,the Mach disk was formed at 70 μs after the projectile shot out. However,the Mach disk was initially formed at 200 μs after the projectile shot out for gun launched in air. Compared with the situation of gun launched in air,the shock core area formed by the underwater launch is significantly smaller, while the temperature of the core region is higher. Especially,the maximum temperature in the compressed wave is up to 3200 K, which is 1500 K higher than that in air. By fitting the curve of the Mach disk position with the time for the underwater launch, it is found that the variation of the Mach disk position follows the law of exponential change within 200μs after the projectile shot out.
In order to understand the distribution characteristics of the muzzle temperature field for gun launched in different environments,numerical simulation and contrast analysis for 12.7 mm gun launched in air and underwater were carried out. W ith the FLUENT software, the numerical simulation was performed using User Defined Function(UDF) and dynamic grid technology. The numerical results show that when the gun is sealed and launched underwater, the velocity of projectile slows down just when it contacts water. At this time,the gunpowder gas after the projectile is slowed up and its temperature is raised,so that the initial injection temperature of the gas reaches 2653 K, which is 417 K higher than that in air(2236 K). Influenced by both the projectile movement and the gas-liquid interface,the Mach disk was formed at 70 μs after the projectile shot out. However,the Mach disk was initially formed at 200 μs after the projectile shot out for gun launched in air. Compared with the situation of gun launched in air,the shock core area formed by the underwater launch is significantly smaller, while the temperature of the core region is higher. Especially,the maximum temperature in the compressed wave is up to 3200 K, which is 1500 K higher than that in air. By fitting the curve of the Mach disk position with the time for the underwater launch, it is found that the variation of the Mach disk position follows the law of exponential change within 200μs after the projectile shot out.
引文
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[2]朱冠南,王争论,马佳佳,等.低压环境下膛口冲击波实验研究[J].兵工学报,2014,35(6):808-813.ZHU Guan-nan,WANG Zheng-lun,MA Jia-jia,et al.Research on muzzle shock wave in low pressure environment[J].Ada Armamentarii,2014,35(6):808-813.
[3]ZHUO Chen-fei,FENG Feng,WU Xiao-song.Development process of muzzle flows including a gun-launched missile[J].Chinese Journal of Aeronautics,2015,28(2):385-393.
[4]吴伟,许厚谦,王亮,等.含化学反应膛口流场的无网格数值模拟[J].爆炸与冲击,2015,35(5):625-632.WU Wei,XU Hou-qian,W AN G Liang,et al.Numerical simulation of a muzzle flow field involving chemical reactions based on gridless method[J].Explosion and Shock Waves,2015,35(5):625-632.
[5]Mizukaki T.Visualization and force measurement of high-temperature,supersonic impulse jet impinging on baffle plate[J].Journal of Visualization,2007,10(2):227-235.
[6]李子杰,王浩.膛口初始流场对火药燃气射流的影响[J].含能材料,2017,25(4):282-290.LI Zi-jie,WANG Hao.Effect of precursor flow field of muzzle on the combustion gas jet flow of gun propellant[J].Chinese Journal of Energetic Materials(Hanneng Cailiao),2017,25(4):282-290.
[7]Harby K,Chiva Munoz-Cobo J L.An experimental investigation on the characteristics of submerged horizontal gas jets in liquid ambient[J].Experimental Thermal and Fluid Science,2014,53(2):26-39.
[8]莽珊珊,余永刚.高压燃气射流在整装液体中扩展过程的实验和数值模拟[J].爆炸与冲击,2011,31(3):300-305.MANG Shan-shan,YU Yong-gang.Experiment and numerical simulation for high pressure combustible gas jet expansion process in a bulk-loaded liquid[J].Explosion and Shock Waves,2011,31(3):300-305.
[9]赵嘉俊,余永刚.锥形多股火药燃气射流与液体工质相互作用的实验研究[J].含能材料,2015,23(11):1055-1060.ZHAO Jia-jun,YU Yong-gang.Interaction between cone-shaped multiple combustion gas jets and liquid[J].Chinese Journal of Energetic Materials(Hanneng Cailiao),2015,23(11):1055-1060.
[10]周良梁,余永刚,曹永杰.喷射结构对充液圆管内气幕特性影响的数值分析[J].含能材料,2016,24(7):657-663.ZHOU Liang-liang,YU Yong-gang,CAO Yong-jie.Influence of injection structure on gas-curtain generation characteristics in liquid tube by numerical analysis[J].Chinese Journal Energetic Materials(Hanneng Cailiao),2016,24(7):657-663.
[11]XUE Xiao-chun,YU Yong-gang,ZHANG Qi.Expansion characteristics of twin combustion gas jets with high pressure in cylindrical filling liquid chamber[J].Journal of Hydrodynamics,Ser.B,2013,25(5):763-771.
[12]XUE Xiao-chun,YU Yong-gang,ZHANG Qi.Study on the effect of distance between the two nozzle holes on interaction of high pressure combustion-gas jets with liquid[J].Energy Conversion and Management,2014,85:675-686.
[13]孔德仁,王昌明,柳光辽,等.水下枪械内弹道分析及其理论建模[J].弹道学报,1998(3):56-60.KONG De-ren,WANG Chang-ming,LIU Guang-liao,et al.Analysis of interior ballistic characteristics of underwater gun and theoretical model's establishment[J].Journal of Ballistics,1998(3):56-60.
[14]陈舟,王昌明,狄长安,等.水深变化时水下发射装置的内弹道计算[J].兵工学报,2002,23(4):462-464.CHEN Zhou,WANG Chang-ming,DI Chang-an,et al.Interior ballistic calculations of an under water gun at various depths[J].Acta Armamentarii,2002,23(4):462-464.
[15]Stace J J,Dean L M,Kirschner I N.Sealing apparatus for exclusion of water from underwater gun barrels[P].11/18/1997:US5687501 A[P].
[16]刘育平,李金新,杨臻,等.水下炮内弹道分析与数值仿真[J].火炮发射与控制学报,2007,28(4):30-33.LIU Yu-ping,LI Jin-xin,YANG Zhen,et al.Interior ballistics analysis and numerical simulation of underwater gun[J].Journal of Gun Launch&Control,2007,28(4):30-33.