Optimal Design Of Active Cooling System On Hydrocarbon-fueled Scramjet

Hypersonic vehic les usua lly cruise at a Mach number higher than5. It willplay an important role on nationa l security and econo mic interests in the future.Hydrocarbon-fue led scra mjet is cons idered to be the best propuls ion unit forhypersonic ve hic les. However, due to the huge aerodyna mic heating in flight andsevere burning in the combustion cha mber, the combustion cha mber wall facesextreme ly severe therma l environments and this causes the temperature of thecomb ustio n chamber wall to rise greatly and even leads to a fa ilure of themateria l. Consequently, effective therma l protection is necessary for combustionchamber.In this dissertatio n, the ideal active cooling mode is used for scientificresearch and in-depth d iscussio n. First of a ll, a combustion cha mber coolingchanne l model based on metal sandwich panels is presented. Also theoreticalanalysis a nd numerica l simulation are carried out resp ectively to get thetemperature and stress distributions of the coo ling channe l. On this basis, theoptimization program is used to calculate the optima l active coo ling systemweight which is various alo ng with the ve locity of hydrocarbon fuel with threedifferent wa ll materia ls (Inconel X-750, Inconel625and Hastelloy X) in thecases with or without insulation coating and different cooling channel sizes.The ana lys is shows that the ins ulation coating does not signifigantly reducethe temperature of the cooling channel materials, but can effectively reduce thestress and improve the sterss d istrib ution of the materia ls. For the materia ls withlow admiss ib le stress such as Hastelloy X, the protective effect of the insulationcoating is obvious. The ins ulation coating can effective ly improve the materia ls’ability to withstand the heat load.The optimization results show that the wa ll materia l choice is based more onstrength than temperature. As a result, materia ls with higher allowable stress likeInconel X-750are more suitable tha n materia ls with lower a llowable stress likeInconel625. Hastelloy X for the combustion chamber wall.