SU27 In-Space Propellant Transfer

NASA maintains a strong desire to develop technology that will enable future in-space cryogenic propulsion systems. Using a cryogenic fuel depot as an example, the in-space propellant transfer process can be divided into various phases: (1) pressurization of the supply tank, (2) acquisition of liquid from the supply tank, (3) chilldown of the transfer line that connects the two tanks, (4) chilldown of the receiver tank, and (5) fill of the receiver tank. Of particular interest is understanding the various two-phase heat and mass transfer processes that occur. 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 desired 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 generally not backed by cryogenic data. Furthermore, NASA is partnering with multiple groups to develop and test reduced gravity cryogenic flight systems.
This internship may focus on performing data analysis and modeling of the various heat and mass transfer processes during the cryogenic propellant transfer process where various two-phase flow phenomena are expected (boiling, evaporation, condensation, flashing). The student may be responsible for analyzing data, exploring operational scenarios, and developing and validating new models or using existing models, which may include including zeroth order, lumped capacitance, or computational fluid dynamics models.
Selected student may be assisting lead cryogenic propulsion scientists to:
1. Perform data analysis on a variety of cryogenic propellant transfer processes.
2. Apply, develop, or validate models for predicting cryogenic propellant tank transfer, including zeroth order, lumped capacitance, and computational fluid dynamics models.
3. Use the models to perform pretest predictions across a range of thermodynamic conditions.
4. Contribute to design, analysis, and operations of cryogenic ground and reduced gravity experiments.
This internship is applicable to the GRC’s core competencies of:
1. In-space propulsion and cryogenic fluid management

Student's Computer and/or Special Skills:
It is preferred that the assigned student be of junior, 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 is required. Proficiency in Python programing language is also preferred. 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 computational models is highly desired. It is preferred that the student be available for 2 or more semesters.

**Eligible Applicants:** Student
**Academic Level:** Undergraduate Junior, Undergraduate Senior, Graduate Master's, Graduate Doctoral
**Activity Type:** In-person
**Citizenship:** US Citizen Only
**Type:** Internships