NEPE固体推进剂化学安定性研究(Ⅱ)——自燃试验研究

研究了NEPE推进剂在不同贮存条件下的自燃行为,得出样品贮存条件与自燃时间有如下关系:当试样尺寸、贮存条件相同时,温度升高,推进剂最小自燃时间缩短。敞开和密闭的贮存条件对推进剂自燃影响显著。贮存在敞开条件下的样品因尺寸不同最小自燃时间不同。比较敞开与密闭贮存时硝酸酯含量随时间的变化认为,推进剂在敞开和密闭条件下最小自燃时间的差异与硝酸酯挥发存在密切的关系。

辐射热流下定向刨花板热解自燃试验及数值模拟

为评估工程板材定向刨花板(OSB)在辐射热流下的自燃着火时间,首先,针对对OSB,开展毫克级的热重分析(TGA)试验,通过模型拟合法得到所建热解机制模型的动力学参数;然后,在锥形加热装置上进行7组恒定辐射热流下的克级自燃试验;其次,将改进的数值模型与测得的表面温度和质量损失率相结合,建立OSB的热力学参数反演模型,得到OSB的导热系数和比热容。最后,采用临界温度和临界质量损失速率参数预测暴露在6组恒定辐射热流下(28、30、35、40、45和50 kW/m;),着火时间分别为194、116、67、47、24、16和129、103、59、42、27、20 s。

煤矸石自燃模拟试验研究

通过煤矸石自燃模拟试验,得出了如下结论:矸石自燃排放出的微量元素已形成较严重的工业污染源,引起了采矿区的空气环境污染,特别是其中的F、Hg、Pb等元素逸出率较高,并提出了一些控制矸石山自燃的工程控制措施,为矸石山自燃的控制提供借鉴。

Experiment study of optimization on prediction index gases of coal spontaneous combustion

The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.

Experimental study on performance that carbon dioxide inhibits coal oxidation and spontaneous combustion

Adopting oil-bath temperature programming experiment and gas chromatography, CO2＇s inhibitory performance on spontaneous combustion of Tingnan Coal Mine sample was analyzed. Through temperature rise rate test experiment, the accuracy, stability and reliability of the improved oil-bath temperature programming system applied in this experiment was proved to be superior to the traditional system. Spontaneous combustion characters parameters test of coal sample in pure air was carried out with this system and offered comparison standard for research in next stage. Temperature programming to coal sample was further conducted in oil-bath with different concentration of CO2. Testing results are compared with parameters of concentration of CO, O2, temperature, CO generation rate and O2 consumption rate tested and calculated in previous experiment in pure air. Methods of proportioning between concentration of CO and O2, CO concentration and temperature, CO generation rate and O2 consumption rate were applied to eliminate obstructions from certain external factors such as inlet of CO2; meanwhile influences of CO2 of different concentrations to coal oxidation and spontaneous combustion were investigated. Also CO2 inhibition technique was used in spontaneous combustion prevention in workface No. 106 of Tingnan Coal Mine, data collected from which indicate that CO2 performs well in inhibiting coal oxidation and spontaneous combustion.

读者信箱

问:爆炸枪弹弹头的结构是什么样的? 宁夏 吴忠市 夏长安 答:爆炸枪弹,即在弹头内装有炸药,具有一定的爆炸威力,用于破坏和引燃目标及显示炸点的枪弹。多为大口径机枪弹,其威力大小取决于内装炸药量的多少。爆炸枪弹主要有时间爆炸枪弹和着发爆炸枪弹两种。 时间爆炸枪弹,即弹头在发射后经过一段时间(约2-3 s)爆炸,多采用延时药柱。

读者信箱

问:弹鼓供弹比弹链供弹的可靠性高,并且所要求的枪械结构也简单,但为什么大口径机枪和榴弹发射器一般不用弹鼓供弹而使用弹链供弹? 云南昆明赵雪勇 答:弹鼓供弹的优点是使武器结构简单、可靠性高,主要缺点是携弹量少,而且更换需要一定的时间,从而使武器战斗射速受到限制,不适应航空机枪、高射机枪这样需要高射速、持续射击武器的需要。

Combustion of nitrate ester plasticized polyether propellants

Nitrate ester plasticized polyether(NEPE)is a kind of high-energy solid propellant that has both good mechanical properties and high specific impulse.However,its unique composition makes its combustion mechanism different from both double-base propellants and composite propellants.In order to study the combustion mechanism of NEPE propellants,we improved the free radical cracking model of previous research to make it capable of predicting the burning rate of NEPE propellants.To study the combustion characteristics and provide data support for the model,an experimental system was built and four kinds of NEPE propellants with different compositions and grain size distributions were tested.The results show that our modified model can reflect the combustion characteristics of NEPE propellants with an acceptable accuracy.The difference between the model and the experimental data is mainly caused by uncertain environmental factors and the ignorance of interactions between components.Both the experimental data and the results predicted by the model show that increasing the backpressure helps to increase the burning rate of NEPE propellants.Furthermore,the grain size of the oxidizer inside the NEPE propellant has a more severe impact on the burning rate but a lighter impact on the burning rate pressure exponent in comparison with the grain size of aluminum.For aluminum-free NEPE propellants,the reaction in the gas phase is dominant in the combustion process while adding aluminum into the propellant makes the solid phase dominant in the final stage.The combustion of fine aluminum particles near the burning surface generates heat feedback to the burning surface which evidently influences the surface temperature.However,the agglomeration of coarse aluminum particles has little effect on the burning surface temperature.