Research Topics

Scholars are encouraged to contact any mentors whose projects they find of interest. To contact the mentor, use the link included at the conclusion of each project description.

Development of new fabrication methods for solid rocket motors (SRMs) by additive manufacturing requires specific material properties and chemistries not delivered by traditional materials. One major hurdle in the 3D printing of propellants, is balancing the rheological requirements needed for the extrusion of propellant composites with the thermomechanical properties of the final cured motor. To obtain a binder system that will possess desirable rheological and mechanical properties, different types of polymers and polymer architectures are currently being tested. Bottlebrush polymers are a class of highly branched polymers that may meet these requirements. Due to their high degree of branching, lower viscosities can be achieved despite very high molecular weights. The objectives of this project are: 1) to synthesize a family of bottlebrushes with olefin-containing side chains of varying chain lengths, and 2) to examine the physical and mechanical properties, both experimentally and through modelling property prediction, in order to assess their potential as binder candidate materials. If successful, this development will afford new polymeric materials that can be specifically tailored for the additive manufacturing of solid-fuel propellants.

The Propellant Ingredient Development Group at the Air Force Research Laboratory is seeking a motivated intern to join our R&D group to assist with a variety of research projects. The candidate will join a diverse, multifunctional team focused on the development of new technologies such as microfluidics and Taylor Vortex fluidics for the production and processing of energetic materials.

The Air Force Research Laboratory is looking for safer replacements for toxic hydrazine rocket fuels. As a result of extensive research, one replacement candidate, the AFRL developed ASCENT propellant, has already been used in orbit on multiple missions. The summer intern would assist in measuring important thermal and physical properties of new propellant candidates. These experimental results will be coupled with a recently developed theoretical machine learning approach that could allow the prediction of physical properties and thermal stabilities of potential new propellants. This work involves experimental and/or theoretical work on designing safer liquid propellants using spectroscopy, calorimetry, and machine learning techniques.
The results expected from this research will lead to a detailed understanding, experimentally and theoretically, of the physical properties and the decomposition characteristics of new propellant candidates that can lead to facile ignition and combustion required for chemical propulsion applications.

Electric propulsion devices have historically been tested in ground-based facilities to characterize their performance before flight. However, ground-based tests cannot fully simulate the environment in space because of the effects of the facility in which the testing occurs. Recent efforts have been made towards quantifying these facility effects by observing thruster operation in order to understand the limitations of ground-based testing. This project will predominantly focus on testing Hall Effect Thrusters to characterize the discharge behavior with varying input conditions which will enable future comparisons between ground and in-space environments. Students will be exposed to various disciplines from designing electrical circuits and assembling diagnostic equipment to software development and data analysis while operating an actual thruster.

Within the past two decades, ionic liquids (ILs) have emerged as viable in-space propulsion propellants that enable the creation of safer, environmentally friendly, economical, and higher-performing thruster devices. However, realizing desirable thruster efficiency remains a challenge and heavily depends on IL propellant properties since many competing propellant breakdown mechanisms during typical operation—thermal, catalytic, or electrochemical decomposition, evaporation, or Coulombic fission—may produce undesirable byproducts that hinder thruster performance, lifetime, and spacecraft mission operations. Thus, a better understanding of the fundamental properties of ionic liquid is crucial for improved thruster design and propellant selection.

In this summer project, a digital engineering approach will be employed using classical, polarizable molecular dynamics (MD) simulations to study water-IL mixtures. MD Simulations will be carried out using the recently improved parametrization of the APPLE&P force field to deduce structural information. While limited experimental data is available for such mixtures, comparisons will be provided for density as a function of temperature and excess molar volume curves. Furthermore, analysis of the various calculated distribution functions will be carried out to elucidate the significance of hydrogen bonding in these systems. The intensity, directionality, and dominant spatial motifs of hydrogen bonds quantified and visualized in this work should illustrate precursors to the rich proton transfer chemistry in these IL mixtures.

Rotating Detonation Rocket Engines (RDRE) are a cutting-edge technology leveraging carefully controlled detonations to extract higher performance than can be obtained from conventional, constant pressure, liquid rocket engine combustors. In RDREs, the high-amplitude/high-frequency pressure fluctuations that usually foreshadow catastrophic failure in traditional rockets are a sign of healthy operation and the intended target mode. However, designing for this operational mode presents several technical challenges that we are addressing through the use of high-fidelity M&S tools. The internship is focused on multi-phase RDREs where the oxidizer, fuel, or both is injected in a liquid state. This increases the complexity beyond traditional gas-gas RDREs. We are looking for students that are interested in contributing to one of the following three areas depending on their skill set. These include:
1. Development and application of traditional Lagrangian based multi-phase methods for the simulation of multi-phase RDRE engines.
2. Development and application of advanced analysis techniques to elucidate RDRE performance and operating characteristics using new and existing data set.
3. Modeling fundamental experiments including, but not limited to, shock/droplet interaction and detonation/droplet interaction.

Distribution Statement A: Approved for Public Release. Distribution Unlimited. PA# AFRL-2023-4167

The AFRL In-Space Propulsion Branch (RQRS) specializes in the early-stage development of satellite thrusters including the development of modeling tools to simulate the behavior of these devices and their impact on the environment that they operate in. As part of this mission, the in-space propellants branch develops and uses a number of codes to simulate these devices. One of these tools, the Thermophysics Universal Research Framework (TURF), allows for collaborators to incorporate modules to understand the flow physics present in in-space thrusters. The selected interns will help enhance the TURF tool by (1) implementomg a one-dimensional Hall-Effect Thruster (HET) model, (2) enhancing the code by adding new electron mobility models, and (3) using the code to provide better initial conditions for HallTPM (HET module in TURF). If time permits, the two codes will be used together in a multi-fidelity modeling framework to enhance processes of design optimization, sensitivity study, and uncertainty quantification of a HET.

This project is aimed at detecting plasma solitons which are formed when small particles move through a weakly ionized plasma environment. This environment can be found in Low Earth Orbit (LEO) which is of great interest to a number of operational and planned satellites. Detecting plasma solitons has applications in on-orbit debris detection and mitigation which is necessary to protect satellites from collisions. In this project, the students will contribute to developing diagnostics and plasma control techniques that can be leveraged in EP thruster design, as well as extending current modeling capabilities for plasma ion acoustic waves in a quasi-1D environment. A student on this project may also be involved in the design of a future, larger-scale version of this experiment.

ASCENT (Advanced SpaceCraft Energetic Non-Toxic) is a newly developed, non-toxic propellant for use in in-space thrusters. This new propellant, developed at the AFRL Rocket Lab, is a replacement for hydrazine, a highly toxic, environmentally unfriendly, propellant. ASCENT has flown in space in the NASA GPIM and Lunar Flashlight missions. ASCENT has numerous applications and research into its use is continuing at AFRL.

Satellite refueling is an important capability to increase the life of satellites in orbit. The first step in developing the capability to refuel satellites in orbit is to develop the capability in ground tests. AFRL is excited to offer a summer internship opportunity to support ASCENT propellant spacecraft refueling ground testing program. Testing will be conducted at AFRL Edwards AFB, California. The individual will have the opportunity to support test activities from planning to execution depending upon the status of the specific testing schedules. The intern will also be responsible for the data collection, input, and analysis of the resulting test data. Testing is planned to both conducted physically as well as in the ASCENT spacecraft refueling Digital Modeling environment

Orbital Transfer Vehicles are being explored as a means to provide sustained operations in space. Student will use state of the art software to develop models of a potential future space logistics architecture to explore the use the potential use of these vehicles. An example of a potential tool that can be is the MIT developed SpaceNet product. These tools enable trading different system types and capabilities to determine what propulsion systems must be developed (or bought) to enable such an architecture. The goal of this project will be to develop a baseline Design Reference Architecture. Depending upon the available time during the internship, the interns may be able to develop permutations of the system to tease out architecture sensitivities. The primary area of focus for the internship is to determine the utility of an Orbital Transfer Vehicle.

Our group has an active basic research project focusing on the synthesis of heavy ionic liquids for satellite high thrust electrospray propulsion (EP). This work originated from a need to produce high thrust while operating in the EP regime. Unfortunately, current ionic liquids utilized for EP are relatively low molecular weight and thus generate low thrust. We have developed new synthetic routes to produce ionic liquids that surpass the current state-of-the-art. The materials our group have produced are being examined by academia and industry in addition to resulting in numerous patent applications, peer-reviewed publications, and conference presentations.

We are seeking an intern to assist with the synthesis, scale-up, and characterization of several target compound families. The intern will receive a unique experience and education learning synthesis and analytical characterization methods such as: organic synthesis and purification, nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). In addition to a monetary stipend and experience, the intern has the potential to contribute to future publications.