喷管扩张段烧蚀的“台阶效应”计算

CALCULATION OF ABLATIVE “STEP EFFECT” IN NOZZLE DIVERGENT SECTION

关键词:  火箭发动机喷管  烧蚀性能  喷管烧蚀计算

Key words:  Rocket engine nozzle  Ablation property  Nozzle ablation calculation

摘要:

当喉衬和扩张段内衬采用具有不同烧蚀率的材料时,常出现“台阶效应”.本文以气动热化学烧蚀机理为基楚,提出应用适当的对流换热和加剧的化学反应计算对台阶效应区进行修正的方法,使台阶效应区的烧蚀率预示更切合实际工况.

Abstract:

The linings of throat and divergent section are usually made of different materials in the construction of many rocket nozzle.A increasing step due to the difference of ablative rates occurs at the conjunction during operation,so that,a ablative indentation appears downstream,which is called ablative "Step Effect".The value of the indentation is considerable.The mechanism of step effect is that as the supersonic gas flow collides to wall,the turbulent degree intensifies.Consequently, the aerothermo-chemical reaction and convective heat-transfer also intensify.The nozzle ablation calculation considering the step effect is based on the ablative calculated programs of throat and-divergent section Hning.The intensifing of turbulent diffusion and chemical reaction caused by the collision of gas flow can be directly modified in original program (for details refer to reference[2]). Meanwhile,the heat-flow in step effect area is calculated fay applying Reynolds simulation relation and method of integration in turbulent layer,by which Bartz formula of convective heat-flow in nozzle can be substituted it.In this paper the heat-flow calculation in step effect area is introduced in detail.