Development of a Hypersonic Aerothermoelastic Framework and Its Application to Flutter and Aerothermoelastic Scaling of Skin Panels

Abstract

In the past decade, there has been a strong interest in reusable air-breathing hypersonic vehicles for in both civil and military applications. However, there are still the unresolved technical challenges associated with this class of vehicles, and one of the challenges is hypersonic aerothermoelasticity. Enhancing the understanding of the aerothermoelastic behavior of hypersonic structures is the ultimate goal of this dissertation.

A computational framework is developed for efficient and accurate aerothermoelastic simulation over extended flight time. The framework is accelerated using two novel techniques. First, the fluid solver is accelerated using a reduced order model augmented with a correction and scaling technique, which accounts for non-uniform temperature distribution, varying flight conditions, and geometric scales. Secondly, a tightly-coupled scheme and linearized stability analysis are developed to enable near-real-time aerothermoelastic simulation of extended flight time and automatic identification of aerothermoelastic instabilities, respectively. The computational framework is applied to study the aeroelastic and aerothermoelastic response of a generic skin panel. The effects of aspect ratio and boundary layer thickness are found to have a significant influence on the critical flutter parameter and the aerothermoelastic stability boundary, i.e. the time elapsed before the onset of structural failure. Furthermore, a proper combination of flow orientation angle and material orientation can significantly extend the aerothermoelastic stability boundary.

Subsequently, an optimization framework is developed for generating hypersonic aerothermoelastic scaling laws using a novel two-pronged approach, which combines the classical dimensional analysis with augmentation from numerical simulations of the specific problem. From the comparison and adjustment of the full-scale prototype and the scaled model, the ``numerical similarity solutions'' are generated to replace the analytical similarity solutions for refinement of the scaling laws. The search for an aerothermoelastically scaled model is formulated as a multi-objective optimization problem, which is solved using a surrogate-based optimization algorithm. The effectiveness of the two-pronged approach is demonstrated by its application to the refined hypersonic aerothermoelastic scaling of a composite skin panel configuration.

This study represents a substantial contribution toward an improved understanding of the aeroelastic and aerothermoelastic behavior of hypersonic skin panels. The findings provide practical implication on the structural design of hypersonic vehicles. Furthermore, the demonstration of the numerical scaling approach shows that it can be eventually applied to testing various components of a hypersonic vehicle. It has the potential for saving considerable funds in the development process of future hypersonic vehicles by replacing some flight tests with wind tunnel experiments.