Research on Thermal Safety of Warhead Charge Based on Cook-off Experimental and Numerical Simulation

doi:10.12382/bgxb.2023.0917

Abstract

Abstract:

In order to study the thermal safety of the warhead charge, a method is proposed for calculating and analyzing the thermal safety of warhead charge and determining the parameters of the reaction modelbased on the temperature of explosive cook-off, the speed of driving piston and the reaction pressureof cook-off. Taking RDX/Al/Binder explosives as an example, the thermal reaction temperature of charge before ignition and the moving speed of piston and the combustion pressure after ignition are measured using the cook-off experiments designed of multi-point temperature measurement and the speed and combustion pressure of driving piston measurement. The thermal decomposition reaction kinetics and combustion reaction model parameters of explosives are calibrated for the quantitative description of the reaction severity through numerical simulation calculation. The cracking of warhead shell is calculated by using the grid node separation calculation method, and the whole cook-off process of warhead charge is numerically simulated. The results show that, for the warhead RDX/Al/Binder explosive charge, the slower the heating rate is, the longer the charge ignition time is, the closer the ignition area is to the center of charge, the more serious the shell rupture is, the greater the kinetic energy of shell is, the greater the kinetic energy of charge is, and the stronger the charge reaction is.

Key words: warhead charge, cook-off experimental, thermal safety, numerical simulation

CLC Number:

O643.2
TJ5

KOU Yongfeng, YANG Kun, ZHANG Bin, XIAO Yiwen, LU Jianying, CHEN Lang. Research on Thermal Safety of Warhead Charge Based on Cook-off Experimental and Numerical Simulation[J]. Acta Armamentarii, 2023, 44(S1): 41-49.

Figures/Tables 13

Fig.1 Layout diagram of experimental system

Fig.2 Shematic diagram of experimental device

Table 1 Material physical parameters

材料	密度/ (kg·m^-3)	比热容/ (J·kg^-1·K^-1)	导热系数/ (w·m^-1·K^-1)
RDX/Al/Binder	-	1900	0.213
钢	8030	502.48	16.27
空气	1.225	1006.43	0.02

Table 2 Thermal decomposition reaction kinetics model parameters of explosives

炸药	活化能/(kJ·mol^-1)	指前因子/(s^-1)
RDX/Al/Binder	147.5	9.01×10¹⁰

Fig.3 Structural diagram of warhead charge

Fig.4 Combustion reaction calculation model of warhead charge

Fig.5 Temperature distribution of RDX/Al/Binder explosive charge profile at different times at 3.0K/min

Fig.6 Experimental and calculated curves of combustion pressures after ignition of RDX/Al/Binder explosive charge at 3.0K/min

Fig.7 Experimental and calculated curves of the speed of driving the piston after ignition of RDX/Al/Binder explosive charge at 3.0K/min

Table 3 Combustion reaction model parameters of RDX/Al/Binder explosive

未反应物状态方程	产物状态方程	燃烧速率方程
R₁=4.85×10⁴GPa	A=0.1GPa	a=0.08GPa^-1·μs^-1
R₂=-3.91GPa	B=0.1GPa	b=0.003GPa^-1·μs^-1
R₃=2.22× 10^-3GPa/K	G=4.0× 10^-5GPa	c=0.667,d=0.366, y=0.8
R₅=11.3	R₇=8.0	e=0.667, g=0.366, z=0.8
R₆=1.13	R₈=5.0	F_i=0.005
T₀=298K	D_p=0	p_i=0.01GPa
		F_amax=0.20
D_u=0		F_bmin=0.15

Fig.8 Profile temperature distribution at ignition time and temperature/heat-time curves in ignition area of RDX/Al/Binder explosive charge at two differnet heating rates

Fig.9 Pressure-time curves for different monitoring positions inside warhead RDX/Al/Binder explosive charge under two different heating rates

Fig.10 Shell deformations at different times after ignition of warhead RDX/Al/Binder explosive charge at two different heating rates

References 19

[1]	TARVER C M, TRAN T D. Thermal decomposition models for HMX-based plastic bonded explosives[J]. Combustion and Flame, 2004, 137(1/2): 50-62. doi: 10.1016/j.combustflame.2004.01.002 URL
[2]	PAKULAK Jr J M, CRAGIN S E. Super small-scale cookoff bomb[R]. Washington, D.C., US: Department of the Navy Washington D.C., 1986.
[3]	JONES D A, PARKER R P. Heat flow calculations for the small-scale cook-off bomb test[R]. AD-A236829.US:DTIC, 1991.
[4]	JONES D A, PARKER R P. Simulation of cook off results in a small scale test[R]. Defence Science and Technology Organization Canberra(Australia), 1994.
[5]	DICKSON P M, ASAY B W, HENSON B F, et al. Measurement of phase change and thermal decomposition kinetics during cook off of PBX 9501[C]// Proceedings of AIP Conference Proceedings. AIP, 2000, 505(1): 837-840.
[6]	AYDEMIR E, ULAS A. A numerical study on the thermal initiation of a confined explosive in 2-D geometry[J]. Journal of Hazardous Materials, 2011, 186(1): 396-400. doi: 10.1016/j.jhazmat.2010.11.015 pmid: 21130568
[7]	CHEN L, MA X, LU F, et al. Investigation of the cook-off processes of HMX-based mixed explosives[J]. Central European Journal of Energetic Materials, 2014, 11(2):199-218.
[8]	PERRY W L, ZUCKER J, DICKSON P M, et al. Interplay of explosive thermal reaction dynamics and structuralconfinement[J]. Journal of Applied Physics, 2007, 101(7):074901-1-074901-5. doi: 10.1063/1.2713090 URL
[9]	PERRY W L, DICKSON P M, PARKER G R, et al. Quantification of reaction violence and combustion enthalpy of plastic bonded explosive 9501 under strong confinement[J]. Journal of Applied Physics, 2005, 97(2):023528. doi: 10.1063/1.1828220 URL
[10]	RAE P J, BAUER C L, STENNETT C. Small scale thermal violence experiments for combined insensitive highexplosive and boostermaterials[EB/OL]. http://www.osti.gov/scitech/biblio/1000930.2010.
[11]	SORBER S, STENNET C, GOLDSMITH M. Developments in a small scale test of violence[C]// Proceedings of American Institute of Physics Conference Series. New York,NY, US: American Institute of Physics, 2012, 1426(1): 563-566.
[12]	CHIDESTER S K, TARVER C M, GREEN L G, et al. On the violence of thermal explosion in solid explosives[J]. Combustion & Flame, 1997, 110(1/2):264-280.
[13]	GARCIA F, FORBES J W, TARVER C M, et al. Pressure wave measurements from thermal cook-off of an hmx based high explosive pbx 9501[C]// Proceedings of AIP Conference Proceedings. New York,NY, US: American Institute of Physics, 2002, 620(1): 882-885.
[14]	FORBES J W, GARCIA F, TARVER C M, et al. Pressure wave measurements during thermal explosion of HMX-based high explosives[R]. Livermore,CA, US: Lawrence Livermore National, 2002.
[15]	GARCIA F, VANDERSALL K S, FORBES J W, et al. Thermal cook-off experiments of the hmx based high explosive lx-04 to characterize violence with varying confinement[C]// Proceedings of AIP Conference Proceedings. New York,NY, US: American Institute of Physics, 2006, 845(1): 1061-1064.
[16]	MAIENSCHEIN J L, WARDELL J F. Deflagration behavior of pbxn-109 and composition b at high pressures and temperatures[R]. Livermore,CA, US: Lawrence Livermore National Lab., 2002.
[17]	MAIENSCHEIN J L, WARDELL J F, DeHaven M R, et al. Deflagration of HMX-based explosives at high temperatures and pressures[J]. Propellants, Explosives,Pyrotechnics: An International Journal Dealing with Scientific and Technological Aspects of Energetic Materials, 2004, 29(5): 287-295.
[18]	寇永锋, 陈朗, 马欣, 等. 黑索今基含铝炸药烤燃实验和数值模拟[J]. 兵工学报, 2019, 40(5): 979-989.
	KOU Y F, CHEN L, MA X, et al. Cook-off experimental an numerical simulation of rdx-based aluminized explosives[J]. Acta Armamentarii, 2019, 40(5): 979-989. (in Chinese)
[19]	HALLQUIST J O. LS-DYNA keyword user's manual livermore[M]. Livermore, CA, US: Livermore Software Technology Corporation, 2007.