The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning cal...The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.展开更多
A complex multiple flame structure is formed during the combustion of AP/HTPB base bleed propellant.The AP monopropellant flame is concentrated in a thin zone above the burning surface of AP crystal to maintain self-s...A complex multiple flame structure is formed during the combustion of AP/HTPB base bleed propellant.The AP monopropellant flame is concentrated in a thin zone above the burning surface of AP crystal to maintain self-sustained decomposition.Due to the low temperature near the burning surface,the diffusion between the decomposition products of AP and the pyrolysis products of HTPB occurs,and a partly pre-mixed diffusion flame structure-leading edge flame(LEF)is formed.The effects of pressure,chemical reaction rate and AP particle size on diffusion flame structure in the range from 20 atm to 100 atm are discussed.The Peclet number increases from 6.64 at 20 atm to 21.91 at 100 atm when AP particle size is 140 mm.The high temperature zone is blown away from the burning surface because the convective transport rate increases with the increase in Peclet number.The chemical reaction rate is enhanced and the diffusion mixing is inhibited as Damkohler number increases.The chemical heat release is more concentrated and the chemical reaction zone becomes narrow when Damkohler number changes from 330 at20 atm to 4700 at 100 atm.When AP particle diameter is decreased to 60 mm,the diffusion time scale is reduced due to the reduced diffusion length scale.So the diffusion mixing is enhanced and a more pre-mixed flame is formed.The burning rate increases because the more pre-mixed heat release increases the heat feedback to the HTPB binder.展开更多
为研究底排装置内底排药剂点火燃烧特性并提高数值计算准确性，用差示扫描量热仪（DSC）和热导仪对比研究了某155 mm底排弹用未老化和经自然老化（在密封塑料袋内室温保存20余年）的高氯酸铵（AP）/端羟基聚丁二烯（HTPB）底排药剂的比...为研究底排装置内底排药剂点火燃烧特性并提高数值计算准确性，用差示扫描量热仪（DSC）和热导仪对比研究了某155 mm底排弹用未老化和经自然老化（在密封塑料袋内室温保存20余年）的高氯酸铵（AP）/端羟基聚丁二烯（HTPB）底排药剂的比热容和导热系数。结果表明，老化底排药剂20℃· min -1升温时 DSC 曲线的最大吸热峰温度和最大放热峰温度分别为253．52℃和437．54℃。基于 DSC 曲线和多项式拟合法得到了40～180℃温区间的比热容与温度的依变关系。老化底排药剂的比热容平均值和导热系数分别为0．9868 kJ· kg -1·℃-1和0．2292 W · m -1· K -1。未老化底排药剂的比热容平均值和导热系数分别为0．8887 kJ·kg -1·℃-1和0．4020 W·m -1·K -1。与未老化药剂相比，老化药剂的比热容增大约11％，而导热系数减小约43％。展开更多
文摘The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.
基金the financial support provided by the National Natural Science Foundation of China(No.51176076)
文摘A complex multiple flame structure is formed during the combustion of AP/HTPB base bleed propellant.The AP monopropellant flame is concentrated in a thin zone above the burning surface of AP crystal to maintain self-sustained decomposition.Due to the low temperature near the burning surface,the diffusion between the decomposition products of AP and the pyrolysis products of HTPB occurs,and a partly pre-mixed diffusion flame structure-leading edge flame(LEF)is formed.The effects of pressure,chemical reaction rate and AP particle size on diffusion flame structure in the range from 20 atm to 100 atm are discussed.The Peclet number increases from 6.64 at 20 atm to 21.91 at 100 atm when AP particle size is 140 mm.The high temperature zone is blown away from the burning surface because the convective transport rate increases with the increase in Peclet number.The chemical reaction rate is enhanced and the diffusion mixing is inhibited as Damkohler number increases.The chemical heat release is more concentrated and the chemical reaction zone becomes narrow when Damkohler number changes from 330 at20 atm to 4700 at 100 atm.When AP particle diameter is decreased to 60 mm,the diffusion time scale is reduced due to the reduced diffusion length scale.So the diffusion mixing is enhanced and a more pre-mixed flame is formed.The burning rate increases because the more pre-mixed heat release increases the heat feedback to the HTPB binder.
文摘为研究底排装置内底排药剂点火燃烧特性并提高数值计算准确性，用差示扫描量热仪（DSC）和热导仪对比研究了某155 mm底排弹用未老化和经自然老化（在密封塑料袋内室温保存20余年）的高氯酸铵（AP）/端羟基聚丁二烯（HTPB）底排药剂的比热容和导热系数。结果表明，老化底排药剂20℃· min -1升温时 DSC 曲线的最大吸热峰温度和最大放热峰温度分别为253．52℃和437．54℃。基于 DSC 曲线和多项式拟合法得到了40～180℃温区间的比热容与温度的依变关系。老化底排药剂的比热容平均值和导热系数分别为0．9868 kJ· kg -1·℃-1和0．2292 W · m -1· K -1。未老化底排药剂的比热容平均值和导热系数分别为0．8887 kJ·kg -1·℃-1和0．4020 W·m -1·K -1。与未老化药剂相比，老化药剂的比热容增大约11％，而导热系数减小约43％。
