C/C喉衬炭沉积形成机理及抑制方法研究

Experimental investigation on formation mechanism of carbon deposition of C/C throat-insert

C/C喉衬在烧蚀后其内表面会出现炭沉积层,沉积层的出现阻碍了喉衬材料微观烧蚀形貌的分析。针对该问题,采用烧蚀实验发动机,在发动机工作末期喷注氮气和减小喷管喉径2种实验方法展开研究,明确了炭沉积层形成机理以及提出抑制该沉积层的方法。通过实验研究证明,炭沉积层成型于发动机工作末期,沉积是由于氧化性燃气中的烃烷类分子在一定的温度和流速条件下分解形成;工作末期喷注氮气起到了抑制沉积的效果,但是骤然冷却,热应力和剪切力使表面部分微观纤维形貌被破坏;由于减少了喉衬处于沉积温度范围内的时间,减小喷管喉径可很好地抑制炭沉积层出现进行微观烧蚀形貌的研究。

The carbon deposition layer appears on inner surface of C/C throat-insert, which hinders the micro-morpbology analysis of materials. A kind of small-size solid rocket motor was used for experimental investigation, and two experimental method were adopted, i.e. injecting nitrogen into nozzle during late working process and reducing nozzle throat diameter. The result clarifies the formation mechanism of carbon deposits and presents method for inhibiting the deposition layer. Experimental investigations prove that the carbon deposits form at the end of working process for the hydrocarbon under certain temperature and flow rate. Injecting nitrogen inhibits deposition effect obviously ,but the micro-morphology of surfaces was damaged by heat stress and shear stress. Because throat insert station time in deposition temperature range is decreased, reducing the nozzle throat diameter may inhibit carbon deposition. The results can be used for microscopic morphology research of C/C nozzle.