| This dissertation focuses on the design and optimization of inward-turning inlets for use in scramjet-powered flight vehicles. Initially, theoretical Busemann inlets are presented along with inviscid streamline-tracing techniques for inlet design. A description of the flow physics of inward-turning inlets is presented along with a discussion of the advantages and disadvantages of such inlets compared to more traditional two-dimensional designs. Then, a novel streamline-tracing method for general inlet design is presented that replaces the Busemann parent flowfield with a simplified parametric representation. Following this, a comprehensive method for performing aerodynamic shape optimization of hypersonic inward-turning inlets is presented. This method incorporates an advanced set of parametric surface tools, grid generation tools, simulation codes, driver scripts, and optimization algorithms into a single fully-automated tool set. A powerful optimization controller is used to launch and monitor the simulation and analysis of the designs on parallel high-performance computing clusters. Then, a nonlinear sensitivity solver algorithm is derived that enables the rapid evaluation of objective function gradients within the aerodynamic shape optimization cycle. In practice, these sensitivities are used by a gradient-based optimization algorithm to efficiently minimize or maximize the objective function. The sensitivity solver is shown to be computationally efficient and able to produce good accuracy despite the presence of strong flow non-linearities. The design and optimization methods presented here are demonstrated on two types of inlets. The first is an axisymmetric inlet with blunt leading edges. In this cases, the optimization is able to improve the efficiency of the inlet and offset losses due to viscous effects and leading edge truncation. In the second case, a three-dimensional streamline-traced inlet is optimized for a given flight condition. This inlet has complex highly swept features with blunt leading edges. The flow in this inlet is highly three-dimensional and has strong shock interactions. Despite these challenges, the optimization is able to substantially improve the efficiency of the inlet at the cruise condition. Finally, extensions of these methods to handle full hypersonic flight vehicles are considered. |
