Modeling and Experiments of Laser-Induced Ignition of Nitramine Propellants

Ritchie, Steven J.; Thynell, Stefan T.; Kuo, Kenneth K.

doi:10.2514/2.5193

Cited by 15 publications

(4 citation statements)

References 18 publications

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“…The power meter, fitted with a 1 cm diameter mask, measured laser power incident on the pellet surface before each experiment. 5,15,20,[24][25][26][27] The predicted critical irradiance, I * , is presented in Fig. Table I with previously published experimental HMX laser ignition data.…”

Section: Laser Ignition Setupmentioning

confidence: 99%

Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

Ali

Son

Asay

et al. 2005

Journal of Applied Physics

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Various thermal ͑radiative, conductive, and convective͒ initiation experiments are performed to demonstrate the importance of the gas phase role in combustion modeling of energetic materials ͑EM͒. A previously published condensed phase model that includes a predicted critical irradiance above which ignition is not possible is compared to experimental laser ignition results for octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine ͑HMX͒ and 2,4,6-trinitrotoluene ͑TNT͒. Experimental results conflict with the predicted critical irradiance concept. The failure of the model is believed to result from a misconception about the role of the gas phase in the ignition process of energetic materials. The model assumes that ignition occurs at the surface and that evolution of gases inhibits ignition. High speed video of laser ignition, oven cook-off and hot wire ignition experiments captures the ignition of HMX and TNT in the gas phase. A laser ignition gap test is performed to further evaluate the effect of gas phase laser absorption and gas phase disruption on the ignition process. Results indicate that gas phase absorption of the laser energy is probably not the primary factor governing the gas phase ignition observations. It is discovered that a critical gap between an HMX pellet and a salt window of 6 mm± 0.4 mm exists below which ignition by CO 2 laser is not possible at the tested irradiances of 29 W / cm 2 and 38 W / cm 2 for HMX ignition. These observations demonstrate that a significant disruption of the gas phase, in certain scenarios, will inhibit ignition, independent of any condensed phase processes. These results underscore the importance of gas phase processes and illustrate that conditions can exist where simple condensed phase models are inadequate to accurately predict the behavior of energetic materials.

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Section: Laser Ignition Setupmentioning

confidence: 99%

Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

Ali

Son

Asay

et al. 2005

Journal of Applied Physics

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“…Shu [12] studied the effect of surface area of am- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 monium perchlorate (AP), initial temperature, heat fluxes and catalyst on the ignition delay time of NEPE propellant within a CO 2 laser ignition system, and got the conclusions that AP acted as a kind of trigger during ignition and the effect of initial temperature on ignition delay time was influenced by heat fluxes. Wang [13] and Ritchie [14] analyzed the effect of laser heat flux on the ignition delay time of NEPE propellant, and found that the ignition delay time was exponentially related to laser heat flux. Xiang [15] discussed the influence of oxygen content in environment gas on the first flame position and ignition delay time of NEPE propellant, but did not study the ignition and combustion mechanism deeply.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Laser Ignition and Combustion Characteristics of NEPE Propellant

Chen

Zhou

et al. 2017

Prop., Explos., Pyrotech.

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The ignition and combustion property of solid propellant is the main content in internal ballistic research, which has a great significance for propulsion application and combustion mechanism. In this study, the detailed gas‐phase reaction mechanism of Nitrate Ester Plasticized Polyether Propellant (NEPE) was developed. It is helpful to understand the intricate processes of solid‐propellant combustion. The factors which may have influences on ignition delay time and temperature distribution of propellant surface was analyzed by laser ignition experiment. Using high‐speed camera and an infrared thermometer, the ignition and combustion process and the surface temperature distribution of NEPE propellant under laser irradiation were measured. Laser heat flux, ambient pressure and initial temperature of NEPE propellant have an influence on the ignition delay time and the surface temperature. Results show that the ignition delay time decreases with the increase of laser heat flux, ambient pressure and initial temperature of NEPE propellant. At the same time, with the increase of laser heat flux, the influences of ambient pressure and initial temperature on the ignition delay time decrease. Besides, laser irradiation, ambient pressure and initial temperature have significant influences on the surface temperature distribution of the propellant.

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“…The build-up of pressure following deflagration through laser heating is considered to give rise to a Shock-to-Detonation Transition (SDT) within the body of the charge. The kinetics of radiative transfer and its effect on energetic materials and pyrotechnics under laser irradiation have been modelled in the past by many researchers (6,7) .…”

Section: Introductionmentioning

confidence: 99%

Studies into Laser Ignition of Unconfined Propellants

Ahmad

Russell

Leach

2001

Propellants, Explosives, Pyrotechnics

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Prior to laser ignition tests, spectral absorption properties of three different solid motor propellants were analysed. The extruded double base (EDB) propellant exhibited >95 % absorption over the 250–550 nm wavelength band whereas, the cast double base (CDB) showed similar absorption over a wider band extending between 375–800 nm. The composite sample (CP) showed a uniform spectral absorption at about 90 % over 250–800 nm band. Ignition tests using an average of 500 nm output from an Ar‐ion laser showed that the double base propellants undergo deflagration prior to ignition due to the presence of carbon black material. Within the laser power density range of 24–125 Wċcm−2, the threshold laser energy densities for deflagration and ignition in the double base propellant were found to␣be between 2–2.5 Jċcm−2, and 40–215 Jċcm−2, respectively. No deflagration was observed for the composite propellant, and the threshold ignition energy was found to be within the range, 11–18 Jċcm−2 for the same range of laser power densities. From the ignition map for this propellant, the threshold energy for ignition at this wavelength was found to be approximately 18 Jċcm−2 and was practically independent of laser power density. In the near infrared wavelength (780 nm) the EDB propellant was not readily ignitable due to its comparatively much higher reflectance at this wavelength. The ignition threshold values were found to be between 19–23 Jċcm−2 for a similar power density level. The results indicate that the ignitability of propellants is enhanced through the promotion of deflagration.

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Modeling and Experiments of Laser-Induced Ignition of Nitramine Propellants

Cited by 15 publications

References 18 publications

Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

Importance of the gas phase role to the prediction of energetic material behavior: An experimental study

Experimental Investigation on Laser Ignition and Combustion Characteristics of NEPE Propellant

Studies into Laser Ignition of Unconfined Propellants

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