Date of Award

January 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

First Advisor

Hallie Chelmo

Abstract

Ice crystals in the upper atmosphere range in size from a few nanometers to a few millimeters, creating potential damage to vehicles traveling at hypersonic speeds; this problem has not yet been investigated with controlled laboratory techniques. This thesis investigates ice crystal impacts on high-speed flight vehicles and their aerodynamics by exploring a new method to combine ice crystal and shock wave experimental apparatuses to achieve experiments of observing ice crystals and shock waves interacting. The objectives of this research are: (1) to consistently produce levitated ice crystals in a setup that can feasibly release the ice crystals into a high-speed flow facility, e.g. a shock tube, (2) to generate ice crystals in the laboratory that correspond to real atmospheric ice particles observed during flight campaigns, and to (3) determine any transient drag effects that might impede introduction of the atmospherically realistic ice crystal to the flow facility. An acoustic levitator levitates a water droplet and nitrogen-cooled air flows over the droplet to freeze it, producing an ice crystal. These ice crystals are dropped into an aircraft probe to capture a 2D image of the ice crystal profile, and a camera records the fall to extrapolate the fall time of the particle. Drag force negligibly affects the ice crystals due to the particle’s small size and the short distance to fall, with the force of gravity being significantly larger. A valve assembly is required to allow the ice crystal to be introduced to the shock wave with minimal impacts to the pressure inside the shock tube. The research done on characterizing the ice crystals made with the acoustic levitator is integral to furthering progress on creating smaller atmospherically realistic particles and being able to observe their interactions with shock waves.

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