SU27 PMDs

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 ability to acquire single phase liquid from a storage tank to a customer receiver tank or an engine. The separation of liquid and vapor phases is governed by the lowest achievable potential energy state. In microgravity, where the liquid/vapor interface inside the tank is generally unknown, surface tension forces dominate over gravitational forces. Special passive devices called propellant management devices (PMDs) are required to separate phases within the upstream propellant tank to ensure single phase liquid delivery and meet the flow rate demands. While PMDs have flight heritage using traditional storable propulsion systems, they have no flight heritage with cryogens. Cryogenic propellants offer significantly higher performance over storables, but the PMD design is more challenging and more complex for cryogenic systems due to lower surface tension, higher susceptibility to boiling and evaporation, and lack of cryogenic data anchored-analysis tools. 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.
NASA is currently designing cryogenic PMDs for multiple mission architectures, including liquid hydrogen-fueled systems, liquid oxygen/liquid methane ascent and descent stages for the Moon and Mars, as well as cryogenic fuel depots. To enable such architectures, testing is being performed and robust fluid/thermal models are being developed to mature cryogenic PMDs in low gravity environments.
Selected students will be assisting lead cryogenic propulsion scientists to:
1. Develop test plans for ground and flight testing of cryogenic PMD.
2. Design, develop, and test ground and flight PMD hardware.
3. Develop and validate cryogenic-data anchored design, sizing, and analytical models for various cryogenic PMDs.
4. Perform basic trade studies to determine the lowest mass, highest reliable, and highest performing PMD for various applications.
5. Contribute to the design and analysis of reduced gravity cryogenic propellant systems.
6. Conduct 1D and computational fluids dynamics simulations of fluid motion with cryogenic PMDs inside propellant tanks in reduced gravity environments.
7. Bench-top test PMDs in lab to measure performance characteristics.
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 (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. It is preferred (but not required) that the student be available for 2 semesters. Previous experience with computational fluids analysis and modeling is highly desirable.

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