Development of Ultrasonically Absorptive Aeroshell Materials for Hypersonic Boundary Layer Transition (BLT) Delay

As the hypersonic flight regime becomes more strategically important, designing robust flight vehicles becomes more important. Maintenance of a laminar boundary layer on hypersonic vehicles is highly desirable, as heating rate and viscous drag both increase dramatically in a turbulent boundary layer. BLT delay via ultrasonically absorptive materials (UAMs) will allow vehicles to fly further and be subjected to a less severe thermal environment, which opens up alternative material options and design approaches. During the Phase I program, GHI will design, model, fabricate, characterize, and test ultrasonically absorptive materials to determine the desired porosity characteristics that correspond to BLT delay in flight regimes of interest. Following the success of the Phase I program objectives, GHI will develop a Phase II plan which will refine and validate this new UAM. The material’s ability to delay BLT while remaining thermally and structurally viable for hypersonic flight will be verified using wind tunnel and arcjet testing. A successful Phase II program will increase the TRL from 4 to 6, preparing this technology for a flight test in its operational environment (TRL 7). The BLT prediction tool advancement made here will benefit the BLT research community, allowing computational studies to compliment ongoing experimental efforts.