Robyn Macdonald News

CU Boulder researcher lands NASA grant to advance hypersonics modeling

Anonymous — Tue, 09 Jan 2024 20:35:16 +0000

CU Boulder researcher lands NASA grant to advance hypersonics modeling Anonymous (not verified) Tue, 01/09/2024 - 13:35

Jeff Zehnder

Robyn Macdonald is pushing the limits of hypersonic research with a new NASA grant.

Macdonald, an assistant professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the University of Colorado Boulder, has been awarded a $600,000 Early Career award from NASA to improve computational modeling of turbulence at hypersonic speeds.

“If you’re flying at Mach 25, there is a lot of kinetic energy present in the gas that gets converted into other forms of energy before reaching the surface of your spacecraft, aircraft, or entry capsule,” Macdonald said. “Fully understanding this process is a really hard problem and is important for things like heat shield design and post-flight reconstruction.”

During hypersonic flight, the temperature of air and other gases around a vehicle can reach thousands of degrees, triggering chemical reactions. Despite recent developments in hypersonic vehicle design, the interaction of these chemical reactions with the surrounding hypersonic turbulent flow is not well understood.

“You need very detailed information, and you’re looking at a variety of scales in both time and space. The calculations become very expensive,” Macdonald said. “As a result there are deficiencies in the current models.”

Most current computational work for design of hypersonic vehicles uses a turbulence model called a Reynolds-averaged Navier–Stokes solution (RANS). RANS is computationally efficient, making it attractive for design processes, but Macdonald said it relies on models which may be invalid for certain hypersonic regimes.

“It’s the current design paradigm, but its applicability is not well characterized for hypersonic flows, and we need better predictions as space missions go further into our solar system to places we don’t understand as well as Earth,” Macdonald said. “We can’t run dozens of experiments in a simulated Mars or Jupiter’s moon Titan environment in advance, so these models are really important.”

Macdonald intends to develop a Wall Modeled Large Eddy Simulation (WMLES) model which includes the relevant chemistry for hypersonic flows. WMLES provides an improvement over RANS by predicting the larger scale turbulent structures while making simplifying assumptions about the small scales of turbulence. However, there does not currently exist a WMLES model which includes the chemical reactions relevant for hypersonic flows. The innovation of this work is the inclusion of the chemistry within WMLES.

It is a significant undertaking requiring supercomputers; Macdonald expects to use CU Boulder’s Blanca Condo Cluster as well as NASA’s Pleiades Supercomputer.

Over the course of the three-year grant, Macdonald and her team will formulate equations, write and verify software to conduct the analysis, and then run test cases to validate their results.

“It’s a big project, and I’m really excited. I like the chemistry. I like turbulence. This is exactly my area,” Macdonald said.

This is Macdonald’s second major hypersonics grant in as many years. She previously received a Young Investigator Research Program award from the Air Force Office of Scientific Research to study gas-phase chemical reactions in the boundary layer at the surface of hypersonic vehicles.

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Video: Computational Modeling of Hypersonic Flows

Anonymous — Wed, 22 Feb 2023 18:49:57 +0000

Video: Computational Modeling of Hypersonic Flows Anonymous (not verified) Wed, 02/22/2023 - 11:49

Robyn Macdonald is an assistant professor in the Ann and H.J. Smead Aerospace Engineering Sciences Department at CU Boulder. Her research interests include hypersonic flows, computation of chemically reacting flows, chemical kinetics, and radiation modeling. Her work has broad applications for hypersonic vehicles for space travel, national defense and other applications.

[video:https://www.youtube.com/watch?v=s-gPrvkmXyw]

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CU Boulder awarded major Department of Defense research grant for hypersonics

Anonymous — Wed, 30 Mar 2022 15:15:14 +0000

CU Boulder awarded major Department of Defense research grant for hypersonics Anonymous (not verified) Wed, 03/30/2022 - 09:15

Jeff Zehnder

Rendering of a hypersonic vehicle in flight. Iain Boyd is leading a five-year, $7.5 million Department of Defense MURI grant to advance the science of hypersonics.

The University of Colorado Boulder has received a five-year, $7.5 million grant to advance the science of hypersonic flight.

Iain Boyd, a professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences and the director of the Center for National Security Initiatives at CU Boulder, is leading the Multidisciplinary University Research Initiative (MURI) from the Department of Defense.

The grant will investigate plasma that forms around sub-orbital vehicles traveling at hypersonic speeds, which can cause radio communication blackouts and impacts aerothermal heating.

“This is a major funding opportunity from the Department of Defense,” Boyd said. “This is fundamental research motivated by national security. We don’t understand how plasma forms at these specific speeds. Plasma also forms around vehicles coming back from space, and we know quite well how that happens, but there’s this new class of hypersonic vehicles. They’re fast, but not as fast as when you come back from space, and it turns out we don’t understand how plasma forms there.”

Hypersonics is an active area of research around the world for national defense purposes. Both China and Russia have successfully introduced hypersonic weapons. The U.S. has not. Boyd views the development of hypersonic weapons as necessary to ensuring parity with other national defense forces.

“For decades we led hypersonics research, but in the last 10 years, China and Russia have leapt ahead,” Boyd said. “Both say they have hypersonic weapons fielded, meaning somebody can push a button and fire one. We don’t have that in the U.S.”

During hypersonic flight, the temperature of air and other gases around a vehicle can reach thousands of degrees, triggering chemical reactions. The research at CU Boulder will investigate the breakdown and collisions of nitrogen, oxygen, and carbon molecules in this environment using advanced computational modeling and experimental tests with molecular beams, shock tubes and hypersonic wind tunnels.

“It will probably take a year just to do experiments on nitrogen and oxygen atoms,” Boyd said. “It takes a lot of time to set these experiments up and do these computations. We want to know how, when and why this plasma forms to build up our ability to predict it.”

Joining in the research are aerospace faculty members Robyn Macdonald, whose efforts are concentrated on computational analysis, and Tim Minton, who is focused on molecular experiments to validate the computational research.

“I am excited about the opportunity to push the frontier and understand these collisional processes that have never before been studied and to contribute to the development of practical modeling tools in the field of hypersonics,” Minton said.

The research grant includes multiple universities in the U.S. and around the world. University of New Mexico, Ohio State University, Stanford University and Oxford University in England are all part of the project.

“This work brings together a team of researchers with broad expertise in experiments and modeling at different scales to tackle an important problem of plasma generation in hypersonic flows,” Minton said. “Our interdisciplinary team is uniquely qualified to do this.”

Boyd notes the partnership with Oxford is a testament to the importance of the research to both the United States and our allies.

“The British government has agreed to fund the work at Oxford,” Boyd said. “Essentially, the U.S. government is leveraging British resources and the British government is leveraging U.S. resources. I think this is very unusual.”

The grant, titled Development of Validated Hypersonic Plasma Kinetics Models Including Atomic Excitation, is one of 28 MURI awards announced by the Department of Defense. They were chosen from 340 applications submitted for fiscal year 2022.

The University of Colorado Boulder has received a five-year, $7.5 million grant to advance the science of hypersonic flight. The grant will investigate plasma that forms around sub-orbital vehicles traveling at...

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Macdonald earns Air Force grant to push the boundaries of hypersonics

Anonymous — Mon, 03 Jan 2022 17:32:07 +0000

Macdonald earns Air Force grant to push the boundaries of hypersonics Anonymous (not verified) Mon, 01/03/2022 - 10:32

Jeff Zehnder

Advancing research at five times the speed of sound.

Robyn Macdonald is studying the fastest vehicles in the world so we can move even faster.

Macdonald, an assistant professor of aerospace engineering sciences at the University of Colorado Boulder, has earned a prestigious Young Investigator Research Program grant from the Air Force Office of Scientific Research (AFOSR). The three-year, $450,000 award is to advance the frontiers of hypersonics, where the minimum velocity is at least five times the speed of sound.

“Hypersonics is an important area of research motivated by both government and private industry high speed vehicle design. Understanding the aerodynamic and thermodynamic state of the gas around the vehicle will eventually help inform design decisions such as material selection for thermal protection systems,” says Macdonald.

During hypersonic flight, the temperature of air and other gases around the vehicle can reach thousands of degrees, triggering chemical reactions. Despite recent developments in hypersonic vehicle design, there are still major gaps our understanding of the underlying physics.

Macdonald’s work will analyze the gas-phase chemical reactions in the boundary layer right at the surface of hypersonic vehicles to help improve heat flux predictions. This research involves molecular dynamic and computational fluid dynamic simulations which are run on supercomputers.

“We have some existing tools and databases available to do very detailed studies in relatively simple cases. The problem is they largely use extrapolated data from much higher temperatures than we’re interested in,” Macdonald said. “We want to extend these databases to analyze what the chemistry looks like at a microscopic level in the temperature range relevant in the boundary layer, and improve the existing models to accurately capture what is happening near the vehicle surface including how different atoms recombine in the boundary layer.”

Hypersonics is an active area of research around the world for national defense purposes and is a growing emphasis for Smead Aerospace. Macdonald completed her PhD in 2019 and joined CU Boulder full-time in January 2021.

“I’m very excited to work on this project. Fundamental research like this is exciting because when you first get data it might not make sense to you. But as you start to analyze what is happening you learn new things about the relevant physics. You understand from a fundamental level what is important and use that information to build a model which could someday be used in hypersonic vehicle design,” Macdonald said.

The Air Force Young Investigator program aims to foster basic research in challenging science and engineering areas, as well as to enhance career development for outstanding individuals. AFOSR received over 175 proposals for their most recent round of funding. Macdonald’s is one of 36 that was awarded.

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Studying computational fluid dynamics at hypersonic speeds

Anonymous — Fri, 02 Apr 2021 15:49:33 +0000

Studying computational fluid dynamics at hypersonic speeds Anonymous (not verified) Fri, 04/02/2021 - 09:49

Jeff Zehnder

Robyn Macdonald is pushing the frontiers of extremely high speed research: hypersonics.

A new assistant professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the University of Colorado Boulder, Macdonald joins a growing group of faculty conducting research into the extreme conditions faced at Mach 5 and above.

“In hypersonic flight, the gas around an aircraft or spacecraft reaches very high temperatures which triggers chemical reactions. We need to understand and model the chemical reactions and other physics occurring such as turbulence,” Macdonald said. “There’s a big push into this type of research.”

The work is of critical importance in both the civilian space exploration and military realm. Multiple countries, including the USA, are working on hypersonic missiles as well as ways to defend against them. In addition, space capsules experience hypersonic conditions during atmospheric entry. As NASA and private space companies grow their footprints in low Earth orbit and beyond, they are seeking new technologies to protect astronauts from the harsh conditions experienced during atmospheric entry.

Macdonald’s research focuses on building a better understanding of hypersonic flight. Although space capsules dating back to Mercury, Gemini and Apollo experienced hypersonic speeds, computer technology is only just now getting to the point where we can fully understand at a fundamental level the conditions faced at those velocities and use this knowledge to inform design decisions.

Macdonald does computational work at the intersection of chemistry and fluid dynamics, leveraging fundamental physics principles to improve predictive modeling capabilities of high-speed flows.

“I enjoy this area of research because I’m interested in understanding the complex underlying physics. In research, you start a problem and never quite know where it will end up. You get to follow the physics to learn new things,” Macdonald said.

She is part of a growing group of hypersonics researchers in Smead Aerospace that includes department chair Brian Argrow and Professors Iain Boyd and Tim Minton.

Macdonald earned her doctorate in aerospace engineering at the University of Illinois Urbana-Champaign in 2019. As a graduate student, she received a prestigious National Defense Science and Engineering Graduate Fellowship from the Department of Defense. After finishing her PhD, Macdonald conducted a post-doctoral fellowship at the University of Minnesota. She started at CU Boulder in January.

Throughout her education, Macdonald has been drawn to research on the frontiers of fluid dynamics.

“Before grad school I knew I wanted to pursue research in fluids. Initially, I thought I wanted to work at NASA but eventually decided I wanted to have the flexibility to pursue my own research interests,” Macdonald said. “I like the freedom to pursue the things I’m interested in. At a university you have more flexibility to explore what excites you and to take on unseen new challenges.”

Just a few months into her position at CU Boulder, Macdonald is building out a research lab and recruiting students for the first time.

“I’d like prospective students to have some experience and a strong interest in research. My research is quite fundamental, so I’m open to students from aerospace engineering as well as mechanical engineering, physics, and chemistry,” she said. “It’s exciting to engage with students as they learn and grow in research. There comes a point when through discussions with students, we learn from each other, which is very rewarding.”

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Welcoming four new faculty to Smead Aerospace

Anonymous — Mon, 26 Aug 2019 16:41:06 +0000

Welcoming four new faculty to Smead Aerospace Anonymous (not verified) Mon, 08/26/2019 - 10:41

The Ann and H.J. Smead Department of Aerospace Engineering Sciences is welcoming four new faculty members. Meet the team and see why we're so excited about these talented new hires:

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