ORCID Number

0009-0005-9336-2143

Date of Award

Summer 2026

Access Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Michael P. Kinzel

Committee Chair Email

kinzelm@erau.edu

Committee Co-Chair

Guillermo Jaramillo

Committee Co-Chair Email

guillermo.jaramillo@correounivalle.edu.co

First Committee Member

Surabhi Singh

First Committee Member Email

singhs36@erau.edu

Second Committee Member

William Engblom

Second Committee Member Email

engbl7de@erau.edu

College Dean

James W. Gregory

Abstract

Rain impact can be a source of surface erosion on hypersonic vehicles, and the severity of each impact depends on droplet velocity, mass, and final shape, all of which are set by how the droplet breaks up under shock loading. Real droplets are expected to carry entrained non-condensable gas (NCG) nuclei from their formation. This dissertation investigates whether the purely mechanical, pressure-driven response of these nuclei, independent of vaporization, is large enough to measurably alter the internal pressure field and early deformation of a shock-loaded droplet.

The droplet and surrounding gas are modeled with a compressible, diffuse-interface, axisymmetric Eulerian framework implemented in MFC (Multi-component Flow Code). Embedded gas nuclei are represented as sub-grid Lagrangian bubbles governed by the Keller–Miksis equation and two-way coupled to the resolved flow; vapor production is excluded. The modeling framework is compared to established benchmarks.

Bubble-free baselines at 𝑀ₛ ∈ {3, 5, 7} show the transmitted shock focusing toward the droplet centerline, producing peak internal pressures several times the post-shock pressure, followed by a reflected rarefaction driving comparably large internal tensions. A parametric study of 36 gas-seeded cases, spanning 𝑀ₛ, four nucleus radii (𝑅₀ ∈ {0.1, 0.2, 1, 2} ΞΌm), and three population sizes (𝑁_𝑏 ∈ {10, 100, 1000}), shows that peak bubble radius is governed by local flow conditions rather than 𝑅₀, that collective pressure perturbation scales sub-linearly with 𝑁_𝑏, and, most significantly, that bubble-induced pressure perturbations produce no measurable change in early-time droplet deformation across the full parameter space.

These results indicate that bulk droplet deformation is governed by external aerodynamic loading rather than internal nuclei response, and that the clean-droplet approximation remains adequate even with substantial nuclei populations. Recommended extensions include incorporating rate-limited cavitation, resolving a single nucleus to benchmark the subgrid bubble model, and pursuing experimental validation with controlled nuclei populations.

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