Applying Uncertainty Quantification to Thermal Protection System Design for a Hypersonic Point-to-Point Passenger Vehicle

Kurzfassung

Thermal Protection System (TPS) design is a critical challenge for hypersonic vehicles, where the system must withstand extreme reentry heating without adding excessive mass. Conventional methods often rely on conservative assumptions, which can lead to overdesigned systems. This paper takes a first exploratory step toward incorporating uncertainty quantification into TPS design, using the SpaceLiner point-to-point passenger transport concept as a reference case. A toolchain was implemented that combines trajectory optimization, aerothermal database generation, and simplified TPS sizing to explore the influence of input uncertainties. The study considers variations in lift and drag coefficients, velocity, flight path angle, altitude, and the transition Reynolds number. Using Sobol sampling, 512 trajectories were generated and analyzed to estimate impacts on TPS mass and regional distribution. As expected, the results suggest that uncertainties in the heat flux estimation and the transition to turbulent flow exert the largest influence on TPS design, while initial altitude plays only a minor role. Some outcomes are counterintuitive: For example, reduced velocity or higher drag lead to lower-altitude trajectories, increasing thermal loads and TPS mass. Clustering analysis further reveals distinct groups of trajectories and TPS results, underscoring the coupled nature of the problem. Overall, the work demonstrates how uncertainty quantification can provide additional insight into the sensitivity of TPS design. While simplified, this approach highlights key drivers and trade-offs, and points toward more balanced methods for future hypersonic vehicle studies.