老化对丁羟推进剂燃速性能影响的试验研究

试验研究了贮存老化对HTPB复合固体推进剂燃速性能影响。分别采用自然老化和加速老化的试验方法,对HTPB推进剂在贮存过程中燃速的变化规律进行了对照分析。自然老化采用库房中贮存的方坯,加速老化采用热加速老化方法,燃速测定为水下声发射方法。试验结果表明,HTPB推进剂在贮存过程中燃速有随时间下降趋势,但变化不明显。自然老化与加速老化结论比较一致,具有可比性,这初步表明加速老化试验可以用于推算HTPB推进剂的燃速老化性能,所获得结论可以为固体火箭发动机进一步寿命评估作参考。分析了老化过程引起燃速性能变化的2种机理:化学老化引起的推进剂组分分解和物理老化引起的裂纹和空洞。前者使燃速产生减小的趋势,后者使燃速有增加的趋势,但总体而言,化学老化是主要的,老化的长期效应是燃速略有减小。

Experimenting on Burning Rate Variation of HTPB Propellant Induced by Ageing Effect

Burning rate of composite propellant is important for the internal ballistic performance of solid rocket motor(SRM).The burning rate variation of HTPB composite solid propellant induced by ageing effect was studied experimentally.Natural ageing method and accelerated ageing method were used respectively to analyze the tendency of the burning rate variation.The specimens of the natural ageing experiments were made from the samples stored in the factory,but specimens used in accelerated heating method needed no previous ageing.Underwater acoustic emission method was used to measure the burning rate.In both experiments, the burning rate of HTPB propellant shows distinct tendency to decrease with time,but the variation is not marked and,when natural ageing is within 15 years,the greatest decrease is only 6.6%,which is within the error limitation of rocket design.The data derived from natural ageing method and accelerated ageing method show good agreement;thus the natural ageing method can be a valid tool for predicting the burning rate variation for HTPB propellant.The mechanism of variation of burning rate was analyzed.There are two factors that influence ageing: decomposition of component induced by chemical ageing,and microcracks and voids induced by physical ageing.The former factor causes the decrease of burning rate,but the latter factor causes the increase of burning rate.On the whole, chemical ageing is dominant and thus the long-term effect is the small decrease of burning rate.