Experimental Study on Burning Evolution in Confined HMX-based PBX Cracks

SHANG Hai-lin1 YANG Jie1 LI Tao1 FU Hua1 HU Hai-bo1

(1.Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, CAEP, Mianyang, China 621999)
【Knowledge Link】polymer-bonded explosive

【Abstract】The aim of the paper is to investigate the evolution law of burning in high explosive (HE) cracks under confinement, obtain the characteristics of convective burning in typical explosive cracks, and deepen our mechanistic understanding of the process for high-intensity reaction of projectile fillings under accidental ignition. The propagation of burning in preformed cracks inside octogen (HMX)-based polymer-bonded explosive (PBX)(with a content of 95% for HMX) under thermal initiation was recorded by a high-speed camera and pressure transducers. It is found that convective burning in 50 μm wide crack of HE under confinement can produce high pressure exceeding 250 MPa with the burning wave speed exceeding 400 m·s−1. A comparison between crack widths revealed that with the increase of crack width, the peak pressure attributed to convective burning decreased but the burning wave speed increased. Detailed analysis of experimental data revealed that there were four stages in the evolution of convective burning in explosive cracks. The first stage was the early stage transportation of initial reaction products through a crack under relatively low pressure gradient without burning on the HE surface. The second stage was the steady convection of product gases with pressure growing due to combustion inside the crack. The third stage was the rapid pressurization due to violent burning of HE with fracture of HE and deformation of the confinement shell. The fourth stage was the confinement failure process under extremely high pressure.

【Keywords】 crack; confinement; convective burning; pressurization;


【Funds】 National Natural Science Foundation of China (11702273, 11802288, 11802283, 11572297) Fund of the Key Laboratory of National Defense Science and Technology for ShockWave and Detonation Physics (6142A0305010717, 6142A03050105)

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(Translated by LI ZP)


    [1] Asay B W, Mcafee J M. Temperature effects on failure thickness and the deflagration-to-detonation transition in PBX9502 and TATB [C]//Proceedings of the 10th International Detonation Symposium. Boston, MA, US: Naval Surface Warfare Center, 1993: 485–489.

    [2] Asay B W. Shock wave science and technology reference library, Vol. 5: non-shock initiation of explosives [M]. Heidelberg, Baden-Württemberg, Germany: Springer, 2010: 245–292.

    [3] Asay B W, Son S F, Bdzil J B. The role of gas permeation in convective burning [J]. International Journal of Multiphase Flow, 1996, 22(5): 923–952.

    [4] Dickson P M, Asay B W, Henson B F, et al. Observation of the behaviour of confined PBX 9501 following a simulated cookoff ignition [C]//Proceedings of the 11th International Detonation Symposium. Snowmass, CO, US: Office of Naval Research, 1998: 606–611.

    [5] Dickson P M, Asay B W, Henson B F, et al. Thermal cook-off response of confined PBX 9501 [J]. Proceedings of the Royal Society A, 2004, 460(2052): 3447–3455.

    [6] Taylor J W. The burning of secondary explosive powders by a convective mechanism [J]. Transactions of the Faraday Society, 1962, 58: 561–568.

    [7] Jackson S I, Hill L G, Berghout H L, et al. Runaway reaction in a solid explosive containing a single crack [C]//Proceedings of the 13th International Detonation Symposium. Norfolk, VA, US: Office of Naval Research, 2006: 646–655.

    [8] Berghout H L, Son S F, Hill L G, et al. Flame spread through cracks of PBX9501 (a composite octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine-based explosive) [J]. Journal of Applied Physics, 2006, 99(11): 114901.

    [9] Berghout H L, Son S F, Asay B W. Convective burning in gaps of PBX9501 [J]. Proceedings of the Combustion Institute, 2000, 28(1): 911–917.

    [10] Jackson S I, Hill L G. Runaway reaction due to gas-dynamic choking in solid explosive containing a single crack [J]. Pro‑ceedings of the Combustion Institute, 2009, 32(2): 2307–2313.

    [11] Andreevskikh L A, Vakhmistrov S A, Pronin D A, et al. Convective combustion in the slot of an explosive charge [J]. Com‑bustion, Explosion, and Shock Waves, 2015, 51(6): 659–663.

    [12] Holmes M D, Parker G R J, Broilo R M, et al. Fracture effects on explosive response (FEER)[R]. LA-UR-18–29694: 2018.

This Article


CN: 51-1489/TK

Vol 27, No. 12, Pages 1056-1061

December 2019


Article Outline



  • 1 Introduction
  • 2 Experiments
  • 3 Results and discussion
  • 4 Conclusions
  • References