Author ORCID Identifier

https://orcid.org/0000-0003-3112-9176

Semester

Fall

Date of Graduation

2022

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Christopher Griffin

Committee Co-Chair

Wade Huebsch

Committee Member

Wade Huebsch

Committee Member

Patrick Browning

Abstract

Significant research over the years has aimed to redefine the flight capabilities of aircraft after sustaining structural damage to critical components. Flight survivability and controllability are key areas of concern when designing fault-tolerant flight control systems to handle a wide range of potential scenarios. However, there is a lack of research on the impact of physically damaged missile systems. Missile counter-defense and intercept capabilities have become more advanced as the United States has focused heavily on these areas over the years. Damaged missiles due to a kinetic intercept capability present an opportunity for analysis of the post-damage implications on flight performance modeling and flight controllability.

Computational fluid dynamics (CFD) has expanded to include a wider range of aerodynamic applications with the increases in computing power. The goal of this research was to extend these developed CFD applications toward the damaged missile problem. Experimental testing can be limited and costly for a full-scale missile study at the required high speeds of end-stage missile flight and thus warranted the CFD approach for the problem. A significant workload is spent on grid creation. This often slows down analysis as time must be spent fine-tuning grid parameters to obtain an accurate solution. Overset meshing, the usage of multiple discrete overlapping grids to constitute a flow domain, was applied to adopt a modular approach toward implementing damages. Individual component grids could be tailored for specific mesh quality, and components could be swapped efficiently without compromising the entire domain.

The objective of this thesis was to analyze the aerodynamic performance of a generic, axisymmetric, cruciform missile after it has undergone various damage states to its outer mold line by using overset meshing techniques to deploy a modular gridding approach for efficiently assessing multiple damaged components within a computational fluid dynamics solver. Damage types examined included differently sized singular through-holes in the fin and wing aero surfaces, missing sections of the fins and wings, entirely missing fins and wings, and fins stuck at various control deflections. This research utilized the computational fluid solver ANSYS Fluent to analyze subsonic external flow around a damaged missile for the terminal glide phase of a surface-to-surface strike. A significant portion of the task was dedicated toward developing a methodology of efficiently implementing physical damages to missile components. Further efforts were made to outline an indexing scheme of labeling damages based on specific geometric criteria.

Furthermore, the types of damage and the subsequent aerodynamic capabilities of the missile in flight were able to be generalized based on certain non-dimensional criteria that could be applied to a wide range of geometries and flight conditions in future missile work. Dimensional analysis relating the geometric characteristics of the damage revealed a dependent relationship between damaged surface area and decreased aerodynamic performance metrics. The aero dataset on damaged missiles could be further expanded over time with more detailed analysis of specific outer mold line damage cases. This analysis could include an assessment of the missile’s ability to still strike its intended surface target after an imparted damage state. Fault-tolerant control logic could be developed based on the aero datasets obtained from this research study. Subsequent flight control studies could assess the ability to still track a target with these reduced aerodynamic capabilities. Predictions would correspond to chances of a missed strike based on distance from the intended target at the end of flight duration.

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