Focus: Fluid MechanicsDuties:- hardware reviews (valves, regulators, etc.)- fluid/thermodynamic analysis of vehicle propellant tanks

Main tasks included writing research proposals for DOE and NASA grants, writing journal papers, managing the Cryogenics lab at UF.

4 main projects:1. Pressure and Velocity mapping of flow through a liquid acquisition channel (Dissertation)- Liquid acquisition device channels are used for delivering single-phase liquid when transferring propellant from a tank to another tank or an engine in zero gravity- Designed, built, and operated experiment for flow through a channel with one porous wall- Measured pressure drop along channel with differential pressure transducers for several flow rates- Measured velocity profile with fluorescent dye injection method and hydrogen bubble method- This data will be used to validate pressure drop model2. Data analysis of two-phase cryogenic flow boiling through pipe- Leading team of 6 students in building statistical correlations for convective heat transfer between two-phase cryogenic flow and pipe inner wall based on the many influential physical parameters including flow rate, pressure, subcooling, vapor mass fraction, densities, viscosities, surface tension, pipe size and length- Correlations based on our own data and on data gathered from the literature- Developed 1-D numerical simulation of the two-phase flow boiling pipe flow heat transfer through a pipe.- Work here was presented at two conferences (see publications)3. Microgravity two-phase cryogenic flow boiling experiment- Led team of 7 students in building two-phase flow boiling experiment with liquid nitrogen for a parabolic flight- Performed stress analysis, heat exchanger analysis, pressure vessel safety analysis, data acquisition system setup, and operational procedure development- Conducted the experiment onboard the aircraft4. CFD of two-phase cryogenic flow boiling through pipe- Leading team of 4 students in developing Computational Fluid Dynamics simulations of cryogenic two-phase (vapor and liquid) film boiling through a pipe- Using ANSYS Fluent with user defined boundary conditions, initial conditions, and interfacial heat and mass transfer functions

The main focus of this internship was to develop, from the governing fluid dynamics equations, a solution to the 2-dimensional flow through a channel with one porous wall. Existing solutions in the literature were too simplified and either assumed a uniform velocity injection through the porous wall or applied incorrect boundary conditions on one or more walls of the domain. With the newly developed solution, the velocity and pressure fields inside of a screen channel LAD could be predicted with better accuracy. This work, therefore, improved the existing capability for designing in-space propellant management devices. This solution has since been used by NASA researchers for simulations of in-space propellant tank drain processes. The work was published in a peer-reviewed journal, the first link below.Tasks included:- Thorough literature review of the porous channel problem- Manipulation of the two-dimensional Navier-Stokes equations (partial differential equations) to obtain an easily solvable ODE.- Solution of the nonlinear ODE with combined Runge Kutta/shooting method (coded with MATLAB)In addition to this main work, I also developed several MATLAB codes to assist NASA Glenn researchers in analyzing screen channel LAD mathematical models. One of the codes simulated the drainage of a liquid hydrogen tank through a screen channel LAD in 1-g to compare against data. The results were reported in a peer-reviewed journal, found in the second link below.

This internship introduced me to screen channel Liquid Acquisition Devices (LADs), which are devices designed for transporting pure liquid inside of a space propellant tank to the outlet of the tank. In the reduced gravity conditions of space, buoyancy effects are negligible and the liquid and gas portions of the propellant can move very freely. The screen channel LAD utilizes the surface tension force of liquids, a dominant force in the absence of buoyancy, to mobilize the liquid and also to prevent gas ingestion. These functions of the screen channel LAD are essential for delivering single-phase liquid propellant to in-space chemical and nuclear rocket engines.The work I did here can be divided into two parts:1 - Gathering and organizing all existing data on screen channel LADs, and then developing mathematical models to predict the performance of the screen channel LADs.2 - Using the models from part 1 to create a performance metric by which to rank different screen types, and then determining an optimal screen type for a liquid hydrogen fuel depot application.Some of the main tasks involved in this internship:- Gathered large amounts of historical data from literature- Wrote the requirements for and ran my own capillary flow experiments- Performed uncertainty analysis on historical and current data- Modified the bubble point equation of a porous screen using statistical regression analysis to account for a newly discovered temperature effect. - Performed a trade study to determine the best screen type based on 5 parametersEach part of the work was published in a peer-reviewed journal. The links to each one are shown below.The work in this internship spurred me on to pursue a Ph.D. in the fluid dynamics/heat transfer area with a dissertation centered on screen channel LADs.

This internship consisted of both hands on and fluid system modeling work. I became familiar with fluid system components such as valves, pressure regulators, filters, relief valves. I had to order these components from vendors and also had to create an inventory of spares inside the warehouse. I learned how to size relief valves and how to model the flow through orifices. I got to see how all of these components are connected in an actual system on the launch pad.Tasks included:-Created MATLAB code to model the GN2 blow-down from accumulators to the F9 engines through the LC-40 nitrogen system-Modeled pipe losses with Fanno flow and accumulator pressure drop from the internal energy change at each time-step-Designed a LN2 dewar self-pressurization system that used an ambient-air vaporizer and pressure regulator-Performed cost analysis of GN2 storage methods including aGN2 generator, an LN2-to-GN2 system, and tube trailers-Used software "Flowmaster" to model the GHe pad system; model was used for design verification of system upgrades-Sized orifices and relief valves for new GHe and GN2 systems-Determined pipe support stresses in the LC-40 liquid oxygen storage and delivery system-Wrote detailed safety reports to verify new GHe and GN2 systems met ASME and OSHA requirements-Ordered, inventoried, installed and repacked valves, filters, regulators, reliefs and other piping partsThis internship sparked my interest in the fluid dynamics area. From there I decided to pursue a Master's degree at UF in the fluids/heat transfer area.