多脉冲飞秒激光切割加工炸药装药过程的热响应

doi:10.12382/bgxb.2023.0795

摘要/Abstract

摘要：

为分析多脉冲飞秒激光切割加工炸药过程的安全性,建立多脉冲飞秒激光切割加工炸药装药的二维数值计算模型,对飞秒激光切割加工HMX、TATB、RDX和TNT 4种炸药装药的情况进行数值计算,获得不同加工状况下炸药装药的热响应规律。实验结果表明:飞秒激光切割加工炸药装药过程中,当激光光斑的移动速度为80~300mm/min时,4种炸药均未发生点火,反应光斑移动速度越慢,热累积效应越明显,且HMX相比其他3种炸药,动态分析区内HMX的热累积效应最明显;当激光重复频率和能量分别为0.1~200kHz和50~200μJ/pulse时,提高飞秒激光的重复频率和能量对切割速率提升效果呈先上升后降低趋势;飞秒激光对炸药装药的切割加工速率和安全性,会受到炸药的性能参数的影响,切割速率与炸药的激光吸收系数呈正相关,切割安全性与炸药的热感度呈负相关。

关键词: 炸药装药, 飞秒激光, 激光加工, 热响应

Abstract:

In order to analyze the safety of multi-pulse femtosecond laser cutting of explosive charge, a two-dimensional numerical calculation model is established for the numerical calculation of femtosecond laser cutting HMX, TATB, RDX and TNT charges. The thermal response rules of explosive charge under different processing conditions were obtained through experiment. The results show that all the four kinds of explosives above are not ignited when the moving speed of laser spot is 80-300mm/min. The slower moving speed of reactive spot led to the more obvious heat accumulation effect. The heat accumulation effect of HMX is the most obvious in the dynamic analysis area as compared with those of other three kinds of explosives. When the repetition frequency and energy of femtosecond laser are in the range of 0.1-200kHz and 50-200μJ/pulse, respectively, the cutting rate increases first and then decreases by increasing the repetition frequency and energy of femtosecond laser. In addition, cutting rate and safety of femtosecond laser on explosive charge are affected by the performance parameters of explosive. Cutting rate is positively correlated with the laser absorption coefficient of explosive while cutting safety is negatively correlated with the thermal sensitivity of explosive.

Key words: explosive charge, femtosecond laser, laser processing, thermal response

中图分类号:

TN249

伍俊英, 姚雨乐, 郑富德, 刘嘉锡, 李钧剑, 王健宇, 陈朗. 多脉冲飞秒激光切割加工炸药装药过程的热响应[J]. 兵工学报, 2024, 45(10): 3462-3473.

WU Junying, YAO Yule, ZHENG Fude, LIU Jiaxi, LI Junjian, WANG Jianyu, CHEN Lang. Thermal Response of Explosive Charge Cutted by Multi-pulse Femtosecond Laser[J]. Acta Armamentarii, 2024, 45(10): 3462-3473.

图/表 23

图1 飞秒激光切割加工炸药装药过程的物理模型示意图

Fig.1 Schematic diagram of physical model of femtosecond laser cutting explosive charge

图2 飞秒激光切割加工炸药装药的计算模型示意图

Fig.2 Schematic diagram of calculation model of femtosecond laser cutting explosive charge

图3 激光光斑重过程的示意图

Fig.3 Schematic diagram of overlapped laser spots

图4 飞秒激光打孔加工炸药装药的计算步骤

Fig.4 Schematic diagram of calculational step of femtosecond laser drilling explosive charge

图5 计算中网格标记示意图

Fig.5 Schematic diagram of grid marking in calculation

表1 4种单质炸药对飞秒激光的吸收系数和反射系数[21]

Table 1 Absorption and reflection coefficients of four kinds of elemental explosives for femtosecond laser[21]

炸药	α/10⁶m^-1	r
TATB	2.264	0.146
HMX	1.434	0.090
TNT	1.724	0.110
RDX	1.626	0.106

表2 4种单质炸药的物性参数

Table 2 Physical property parameters of four kinds of elemental explosives

炸药	密度/ (kg·m^-3)	热容/ (J·kg^-1·K^-1)	热导率/ (W·m^-1·K^-1)	热扩散系数/ (m²·s^-1)	点火温度/ K
HMX	1905	1050	0.345	1.72×10^-7	573
TATB	1937	1170	0.544	2.40×10^-7	632
RDX	1820	1250	0.213	9.36×10^-8	486
TNT	1580	1380	0.500	2.29×10^-7	513

表3 4种单质炸药的爆热值[29]

Table 3 Explosion heat values of four kinds of elemental explosives[29]

炸药	TATB	HMX	TNT	RDX
爆热/(kJ·mol^-1)	1165.7	1828.0	1233.1	1635.6

表4 4种单质炸药的多步热分解反应动力学参数

Table 4 Kinetic parameters of multi-step thermal decomposition reaction of four kinds of elemental explosives

炸药	反应步	活化能 E/(kJ·mol^-1)	指前因子 Z/s^-1	反应热 Q/(kJ·kg^-1)
	1	204	7.99×10²⁰	-42
HMX	2	221	1.41×10²¹	-251
	3	186	2.61×10¹⁶	558
	4	143	1.60×10¹²	5602
	1	252	7.02×10²⁰	-210
TATB	2	176	8.75×10¹²	-210
	3	142	4.36×10¹¹	2933
	1	184	1.58×10¹⁵	-126
TNT	2	144	1.96×10¹¹	3767
	3	140	2.39×10¹¹	3896
	1	197	5.75×10¹⁹	-419
RDX	2	184	4.74×10¹⁷	1257
	3	143	1.58×10¹⁵	5028

图6 0.25s时刻HMX中加工表面的温度分布

Fig.6 Temperature distribution of HMX processing surface at 0.25s

图7 59s时刻HMX装药的切割加工形貌

Fig.7 Cutting morphology of HMX charge at 59s

图8 动态分析区域位置示意图

Fig.8 Location diagram of dynamic analysis area

图9 10s内动态分析区域HMX的温度和放热量随时间变化

Fig.9 Temperature and heat release curves of HMX in the dynamic analysis area within 10s

图10 直至点火前动态分析区域内HMX的温度和放热量随时间变化

Fig.10 Temperature and heat release curves of HMX in the dynamic analysis area before ignition

图11 不同光斑移动速度下动态分析区内HMX的放热量随时间变化

Fig.11 Heat release curves of HMX in the dynamic analysis area under different spot moving speeds

表5 不同光斑移动速度下光斑的重叠率(1kHz)

Table 5 Overlap rates of light spots at different moving speeds (1kHz)

光斑移动速度/(mm·min^-1)	80	120	300
重叠率	0.9661	0.9491	0.8729

图12 10s内不同光斑移动速度下激光光斑在HMX加工表面移动位置示意图

Fig.12 Schematic diagram of laser spot moving on HMX processing surface at different spot moving speeds within 10s

表6 不同光斑移动速度下飞秒激光对HMX的切割速率(100μJ/pulse, 1kHz)

Table 6 Cutting rates of femtosecond laser on HMX at different spot moving speeds (100μJ/pulse, 1kHz)

光斑移动速度/(mm·min^-1)	80	120	300
切割速率/(μm·s^-1)	12.55	14.11	16.36

图13 不同重复频率下动态分析区内HMX的温度随时间变化

Fig.13 Temperature curves of HMX in the dynamic analysis area under different repetition frequencies

图14 不同能量下动态分析区内HMX的温度随时间变化

Fig.14 Temperature curves of HMX in the dynamic analysis area under different energies

图15 飞秒激光对HMX装药的切割速率

Fig.15 Scatter diagram of cutting rate of femtosecond laser on HMX charge

图16 动态分析区内4种炸药的温度随时间变化

Fig.16 Temperature curves of four kinds of explosives in dynamic analysis area

表7 飞秒激光对4种炸药的切割速率(100μJ/pulse, 1kHz, 300min/mm)

Table 7 Cutting rates of femtosecond laser on four kinds of explosives (100μJ/pulse, 1kHz, 300min/mm)

炸药	HMX	TATB	RDX	TNT
切割速率/(μm·s^-1)	16.36	17.29	16.51	16.83

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