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Computational Fluid Dynamics Modeling of Cryogenic Propellant Transfer

You must apply through the external link. This position is on-site. Please apply by November 11, 2022 for best consideration.

NASA maintains a strong desire to develop technology that will enable future in-space cryogenic propulsion systems. Of interest in the current project is the role of boiling heat transfer during cryogenic propellant storage and transfer. Due to the low normal boiling point of all cryogens, they are particularly susceptible to boiling heat transfer. For example, during propellant tank chilldown, fluid that comes in contact with the hot tank walls will boil vigorously. Meanwhile, in microgravity where the liquid vapor interface inside the tank is unknown, tank fill must be done with the vent valve closed to avoid venting liquid. The combination of cryogenic fluid and large temperature differences between liquid and tank imply that there will be complex flow boiling, heat transfer, and two-phase flow patterns.
Accurate, reliable cryogenic fluid based models are thus required to design, size, and analyze NASA’s future cryogenic propulsion system architectures. The penalty for poor models results in higher safety margin (size depot larger to carry more propellant), higher safety factor (more insulation needed, which increases launch vehicle mass), and higher cost. Current models used in thermal design codes are based on room temperature fluids, and not backed by cryogenic data. The distinct fluid physics of cryogens poses a unique problem when creating accurate computational models.
The student will assist leading cryogenic fluid management engineers to assist in creating a computational fluid dynamics model of the propellant transfer project. The particular focus will be on modeling the heat and mass transfer during the chilldown of cryogenic propellant tanks where various two-phase flow phenomena are expected (boiling, evaporation, condensation, flashing). The student will be responsible for creating solid models of the propellant tanks, importing them into the CFD software, implementing all initial and boundary conditions, validating the model against historical data, and assessing the fidelity of the CFD model capabilities.
The ultimate goal of this project is to develop and validate accurate, low-error, data-anchored tools that can be used to size future cryogenic propellant based transfer systems.
This internship is applicable to the GRC’s core competencies of:
1. In-space propulsion and cryogenic fluid management
Expected opportunity outcome (i.e. research, final report, poster presentation, etc.):
The expected outcomes are as follows: (1) Develop and validate the CFD models for multiple fluids and multiple test cases, (2) document all results in a high quality technical report, and (3) contribute to the design, validation, and testing life cycle phases of future propellant transfer architectures.

Student's Computer and/or Special Skills:
It is preferred that the assigned student be of senior, or graduate level and have already taken 1-2 semesters of undergraduate level Thermodynamics, Fluid Mechanics, and Heat Transfer. Transport Phenomena can be substituted. Student must be proficient with all basic Microsoft Office programs, specifically Powerpoint, Word, and Excel. Knowledge of Matlab (or equivalent data processing/numerical code like Python) is required. Student must have taken at least one semester in numerical techniques, or have working knowledge on basic statistics, curve fitting techniques, basic optimization. A basic understanding of two-phase flow is also desirable but not required. Prior experience with CFD is preferred. It is preferred (but not required) that the student be available for 2 semesters.

Eligibility requirements:

  • U.S. Citizen
  • Cumulative 3.0 GPA (on a 4.0 scale)
  • Full-time students (high school through graduate)
  • Enrollment in a degree granting institution
  • 16 years of age at the time of application (no exceptions)