装药参数对水下机枪密封式膛口流场影响的数值分析
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摘要
为了研究装药参数变化对水下机枪密封式发射膛口流场特性的影响,建立了水下机枪密封式发射的数学物理模型。运用流体力学计算软件Fluent,结合用户自定义函数和动网格技术,针对12.7 mm滑膛式机枪,分别采用15.5 g、13.0 g和11.0 g装药量对其水下密封式发射膛口流场进行了数值模拟。计算结果表明:不同装药量条件下,水下机枪密封式发射时,在弹头飞离膛口截面的过程中,水对弹前初始空气和弹头轴向运动的阻碍较大,导致弹头减速、火药燃气在弹后空间聚集、膛口燃气压力升高,而火药燃气形成射流后的喷射压力衰减遵循指数衰减规律;膛口射流形态受弹头速度和燃气喷射压力的耦合影响,均逐渐由梯形空腔转变为葫芦状空腔,且射流的轴向最大位移遵循指数衰减规律,马赫盘的初步形成时间也基本一致;随着弹头初速和燃气初始喷射压力的降低,火药燃气在射流头部聚集且径向扩展明显,并伴随形成二次射流,而弹底对马赫盘形状的影响时间缩短,激波核心区结构也更快地接近于正激波。因此可见,装药量对膛口流场分布的影响具有一定的规律性。
A mathematical-physical model is established to study the influence of charge parameters on the flow field characteristics for 12.7 mm underwater machine gun.Fluent software,combined with userdefined function and dynamic grid technology,is used to simulate the flow fields around the sealed muzzles of underwater machine guns with the charge quality of 15.5 g,13.0 g and 11.0 g,respectively.The results show that the axial movements of initial air and projectile are impeded by the high-density water,resulting in the slowdown of projectile and the gathering of gunpowder gas at muzzle during the projectile flying through the muzzle.The attenuation of gas jet pressure follows the exponential decay rule after a projectile is fired from the muzzle.When the jet is affected by both the projectile velocity and the gas jet pressure,its shape gradually changes from a trapezoidal cavity to a gourd-like cavity,and the maximum displacement of jet follows the exponential decay rule.The initial formation time of Mach disk is basicallythe same for the three charge conditions.With the reduction in the initial velocity of projectile and the initial injection pressure of gas,the gunpowder gas gathers in the jet head and radially expands to form the secondary jet.Meanwhile,the impact time of projectile base on the shape of Mach disk is shortened,helping the shock core faster approximate to normal shock wave.It can be seen that the influence of charge quality on the distribution of the flow field around the muzzle has a certain regularity.
A mathematical-physical model is established to study the influence of charge parameters on the flow field characteristics for 12.7 mm underwater machine gun.Fluent software,combined with userdefined function and dynamic grid technology,is used to simulate the flow fields around the sealed muzzles of underwater machine guns with the charge quality of 15.5 g,13.0 g and 11.0 g,respectively.The results show that the axial movements of initial air and projectile are impeded by the high-density water,resulting in the slowdown of projectile and the gathering of gunpowder gas at muzzle during the projectile flying through the muzzle.The attenuation of gas jet pressure follows the exponential decay rule after a projectile is fired from the muzzle.When the jet is affected by both the projectile velocity and the gas jet pressure,its shape gradually changes from a trapezoidal cavity to a gourd-like cavity,and the maximum displacement of jet follows the exponential decay rule.The initial formation time of Mach disk is basicallythe same for the three charge conditions.With the reduction in the initial velocity of projectile and the initial injection pressure of gas,the gunpowder gas gathers in the jet head and radially expands to form the secondary jet.Meanwhile,the impact time of projectile base on the shape of Mach disk is shortened,helping the shock core faster approximate to normal shock wave.It can be seen that the influence of charge quality on the distribution of the flow field around the muzzle has a certain regularity.
引文
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[19]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,WANG 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.(in Chinese)
[2]郭则庆,王杨,姜孝海,等.小口径武器膛口流场可视化实验[J].实验流体力学,2012,26(2):46-50.GUO Ze-qing,WANG Yang,JIANG Xiao-hai,et al.Visual experiment on the muzzle flow field of the small caliber gun[J].Journal of Experiments in Fluid Mechanics,2012,26(2):46-50.(in Chinese)
[3]姜孝海,李鸿志,范宝春,等.基于ALE方程及嵌入网格法的膛口流场数值模拟[J].兵工学报,2007,28(12):1512-1515.JIANG Xiao-hai,LI Hong-zhi,FAN Bao-chun,et al.Numerical simulation of muzzle flow field based on ALE equation and chimera grids[J].Acta Armamentarii,2007,28(12):1512-1515.(in Chinese)
[4]Jiang X H,Chen Z H,Fan B C,et al.Numerical simulation of blast flow fields induced by a high-speed projectile[J].Shock Waves,2008,18(3):205-212.
[5]Rehman H,Hwang S H,Fajar B,et al.Analysis and attenuation of impulsive sound pressure in large caliber weapon during muzzle blast[J].Journal of Mechanical Science and Technology,2011,25(10):2601-2606.
[6]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].Acta Armamentarii,2014,35(6):808-813.(in Chinese)
[7]Stace J J,Dean L M,Kirschner I N.Sealing apparatus for exclusion of water from underwater gun barrels:US,US 5687501[P].1996-03-06.
[8]Fu J,Howard R J,Rapp J W,et al.Underwater gun comprising a plate-type barrel seal:US,US 7874091[P].2011-01-25.
[9]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.(in Chinese)
[10]易文俊,熊天红,王中原,等.小空化数下超空泡航行体的阻力特性试验研究[J].水动力学研究与进展A辑,2009,24(1):1-6.YI Wen-jun,XIONG Tian-hong,WANG Zhong-yuan,et al.Experimental researches on drag characteristics of supercavitation bodies at small cavitation number[J].Chinese Journal of Hydrodynamics,2009,24(1):1-6.(in Chinese)
[11]Tang J N,Wang N F,Wei S.Flow structures of gaseous jets injected into water for underwater propulsion[J].Acta Mechanica Sinica,2011,27(4):461-472.
[12]Xue X C,Yu Y G,Zhang Q.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.
[13]Harby K,Chiva S,Mu1oz-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.
[14]Zhou L L,Yu Y G.Experimental study on gas-curtain generation characteristics by multicombustion-gas jets in the cylindrical liquid chamber[J].Ocean Engineering,2015,109:410-417.
[15]周良梁,余永刚,刘东尧,等.水下火炮气幕式发射过程中燃气射流与液体工质相互作用特性研究[J].兵工学报,2016,37(8):1373-1378.ZHOU Liang-liang,YU Yong-gang,LIU Dong-yao,et al.Research on gas-liquid interaction characteristics during the gas curtain launching process of underwater gun[J].Acta Armamentarii,2016,37(8):1373-1378.(in Chinese)
[16]Zhao J J,Yu Y G.The interaction between multiple high pressure combustion gas jets and water in a water-filled vessel[J].Applied Ocean Research,2016,61:175-182.
[17]Hu Z T,Yu Y G.Expansion characteristics of multiple wall jets in cylindrical observation chamber[J].Applied Thermal Engineering,2017,113:1396-1409.
[18]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.(in Chinese)
[19]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,WANG 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.(in Chinese)