Thermal stress analysis of the FGLCS in hypersonic vehicles: Their application to fuel injection struts in scramjets

This paper proposes a novel functionally graded layer composite structure (FGLCS) for use in hypersonic vehicles. It consists of a passive thermal protection layer made from ultra-high temperature ceramic composites, an interface layer of high temperature insulating material and an active thermal protection layer of alloy. The transient thermal stress alleviation characteristics of an FGLCS plate and an FGLCS strut under aerodynamic heating conditions were studied using a finite element method. Compared to a traditional ultra-high temperature ceramic (UHTC) plate and strut, FGLCS can greatly reduce the thermal stress level of structures, the stress relief can be up to 84% in a case study considered in this paper. In addition, the long-term and reusable performance of a prepared FGLCS strut, with much lower thermal stress, was completely validated for the first time by an oxy-propane testing system in a combustion environment.