【摘要】 本文根据实际固体火箭发动机的工作特点,以 Summerfield 的气相点火理论[1]为基础,建立了用炽热含氧流动气体点燃复合固体推进剂的气相点火模型;并着重从研究影响点火过程的主要因素方面考虑,通过简化,从该模型中导出了计算复合推进剂点火延迟时间的解析表达式;然后,就点火燃气的压力和氧化剂浓度这两种因素对点火延迟时间的影响,通过实验进行了验证。在理论与实验结果定性一致的基础上,本文认为,对于大多数以过氯酸铵为氧化剂的复合推进剂来说,是气相反应控制点火过程,因为利用炽热气体点火时,燃气的压力和氧化剂浓度是影响点火过程的主要因素。这一结论为如何调整设计参数,改进火箭发动机点火器的点火性能指出了方向。更多还原

【Abstract】 An understanding of the details of the physical and chemical processes,by which a solid rocket motor(SRM)is brought to the stage of steady combustion,is of great importance to the designers of propellant ignition systemsThe present level of technology does not as yet permit even an approximatebut reliable prediction of the ignition delay in preliminary design.Yet,withthe help of available theoretical and experimental research results,it is quitepossible to put forward some broad guidelines for the designers of propellantignition systems.The present paper presents some further research on the ignition problemsof composite solid propellants in the SRM.The authors modify Summerfield’sgas-phase ignition model[l]of composite solid propellants,and our researchdeals mainly with the effects of the pressures and oxygen concentrations ofhot ignition gases in practical SRM on the ignition delay of composite solidpropellants.The authors are not aware of the existence of research dealingwith the above-mentioned effects in practical SRM.The present paper first explores theoretically the gas-phase ignitionmechanism of composite solid propellants,and then establishes gas-phaseignition model closer than Summerfield’s to practical SRM operating condi-tions.With such a model,we obtain an approximate analytical formula forcalculating ignition delay of composite solid propellants.Experiments on the effects of the pressures and oxygen concentrationsof hot ignition gases on the ignition delay of three different composite solidpropellants are made with a gas-liquid type igniter,which incorporates ashifting device and is capable of supplying a convective ignition stimulus tothe internal and external surfaces of a thin-wall tubular solid propellantgrain.In the experiments,by selecting the first drastic rise of the pressureas the experimental ignition criterion and keeping other factors constant,thevariations of the ignition delay with ignition gas pressures and oxygen con-centrations are measured. Both theoretical and experimental results show that the pressures andoxygen concentrations of hot ignition gases are important factors affectingthe ignition process of composite solid prorellants.obviously,a clear under-standing of these effects is of considerable importance to both theoreticalresearch and practical application.From the foregoing,the conclusion is that gas-phase reactions are key tocontrolling ignition processes in the SRM with composite solid propellants.This conclusion also points out the way for improving the ignition charac-teristics of SRM by choosing appropriate design parameters for igniters.更多还原