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Thinking 3-D

New imaging system to improve flow diagnostics

By Carol Nelson

A group of Auburn Engineering researchers is developing a new imaging system that could have wide-reaching impacts, ranging from health care to the aerospace industry.

“From blood flow through artificial heart valves to the mixing and combustion of fuel and air in a modern jet engine, many flows are both unsteady and three-dimensional,” said Brian Thurow, professor and chair of the Department of Aerospace Engineering. “Modern diagnostics used to study these flow fields are slow, two-dimensional, and in the case of multi-camera 3-D diagnostics, both expensive and complex. We are trying to simplify fundamental 3-D imaging technology into a more compact and economical hardware, while also increasing the speed of the system to help us look at more practical problems.”

A research team led by Thurow has been awarded a $1.1 million grant from the National Science Foundation to develop a new, single-camera imaging system capable of capturing high-speed and 3-D measurements in practical flow fields.

In recent years, Thurow’s lab developed a prototype that has been demonstrated as a simple, robust and effective 3-D imaging system. The grant is helping researchers to develop the hardware and software of the technology, which allows them to capture all the information they need in one snapshot, using just one piece of equipment.

“In one click of the shutter, can you get all of the information about what’s happening in three dimensions? The unique piece of what we’re developing is that we don’t have to have hundreds of cameras looking at an experiment at one time, and we don’t have to move the cameras around to a number of different positions,” Thurow said. “We can do it all in a simple, compact hardware, which will also allow the system to be optimized for various facilities and techniques.”

Thurow said the technology allows the team to expand their research beyond aerospace to other areas, including biomedical engineering and cardiovascular fluid mechanics.

“Dr. Thurow and I are looking at ways to apply his technology in biomedical engineering,” said Vrishank Raghav, assistant professor of aerospace engineering. “No one has done that before. It’s a newer technology, so we are trying to incorporate these ideas into understanding cardiovascular diseases.”

"Dr. Thurow and I are looking at ways to apply his technology in biomedical engineering. No one has done that before."

Raghav’s primary focus is prosthetic valve design, essentially prosthetic or artificial heart valves that are implanted into patients with a failing heart valve. Natural wear and tear on the heart leads to calcium deposits and damage to valves, which can begin to malfunction.

“Younger patients are usually able to undergo open heart surgery, but older patients usually cannot withstand it,” Raghav explained. “There is a new technology that is not as invasive, called transcatheter valve replacement, where doctors make an incision in the thigh or groin area, and snake a catheter up to the heart and replace the valve. While I was at Georgia Tech previously, I began collaborating with Dr. Thurow to apply his technology to improve the valve design for this transcatheter approach.”

Raghav said that optical access is extremely limited when replicating the flow in the heart using a bench-top system, since they don’t have multiple points of entry like they do in the case of some aerodynamic experiments in aerospace engineering.

“This technique offers significant advantage because it’s also a single-camera technique, where other techniques use four. We can measure volumetric flows or 3-D flow fields and can take multiple snapshots of the velocity field around the heart valve within a single cardiac cycle, or one heartbeat,” he said.

Thurow said the system will have an immediate impact on the understanding and treatment of cardio/cerebrovascular diseases; the understanding and modeling of non-reacting compressible flow fields associated with high-speed vehicles; and the understanding and design of stable and efficient combustion processes. Long term, the technology will support collaborative research activities at both Auburn and Purdue University.

Other researchers involved in the project include David Scarborough, also of the Department of Aerospace Engineering, Stanley Reeves of the Department of Electrical and Computer Engineering, and Pavlos Vlachos of the Purdue University School of Mechanical Engineering.

“At Auburn, biomedical fluid dynamics, unsteady 3-D rotating flows and combustion instability are emerging topics being led by Vrishank Raghav and David Scarborough,” Thurow said. “Our counterparts at Purdue have a track record of applying advanced diagnostics to high-impact problems and are well established in their respective fields. There is this nice synergy between what they’re doing and what we’re doing. We are able to focus on the instrumentation and hardware development, and then the applications will push out through the work of our colleagues at Purdue. The collaboration is mutually beneficial.”