Date of Award
2026
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Aerospace Systems Engineering
Committee Chair
Robert Frederick
Committee Member
L. Dale Thomas
Committee Member
David Lineberry
Research Advisor
Robert Frederick
Subject(s)
Bubbles--Dynamics, Nuclear propulsion
Abstract
This study experimentally characterizes gas-injected bubble dynamics in analog fluids to establish baseline behavior for Centrifugal Nuclear Thermal Propulsion (CNTP) systems. Nitrogen was injected through mass flow ranges of 3.3E-05 to 9.6E-05 lbm/s through various injector arrays in a transparent tank apparatus using water or sodium polytungstate (SPT-3) to vary fluid properties. Four injector configuration cases were tested on a 4-in deep, clear-sided chamber at atmospheric surface pressure to examine the effects of fluid viscosity and density, circular injector diameter, injector location, and mass flow rate on bubble diameter, rise velocity, and plume structure. Bubble equivalent diameters, positions, and velocities were determined using high-speed imaging and automated image processing, and nondimensional analysis was performed using Reynolds and Eötvös numbers. Results showed that by increasing the injector mass flow rate from 1.7E-05 to 4.8E-05 lbm/s, the average of both the median bubble diameters and the median rise velocities increased from ~0.2 to 0.4 in and from ~5 to 8 in/s, respectively. Water bubbles reached Reynolds numbers of 900 to 2000, while SPT-3 bubbles remained below 200 and showed less deformation. Injector location affected bubble trajectory symmetry and bubble interaction, and SPT-3 testing revealed injector clogging that increased variability. This work provides baseline data for CFD model validation and future experiments that will include higher surface pressures and a rotating chamber and higher surface and pressures.
Recommended Citation
Kondrat'yev, Julia, "Experimental characterization of gas-injected bubble dynamics in various fluids and injector arrays for centrifugal nuclear propulsion applications" (2026). Theses. 824.
https://louis.uah.edu/uah-theses/824