INEEL and UI receive grant to improve jet engines

November 05, 2000

A grant from the Air Force Office of Science Research will help researchers improve the design of jet engine turbine blades.

The collaborative project takes advantage of a unique resource at the Department of Energy's Idaho National Engineering and Environmental Laboratory. University of Idaho researchers will use the INEEL's Matched Index of Refraction Flow System (MIR) to investigate how air flows around the blades. The INEEL facility is the largest MIR system in the world.

The researchers plan to study disturbances in flow around a quartz model that simulates a turbine blade's surface. But instead of relying on a supercomputer or wind tunnel to study flow, they will use baby oil and lasers.

The MIR facility takes advantage of a simple light trick. Keeping the oil at 86 degrees means that light, such as a laser beam, passes through the baby oil and the quartz with the same resistance. For example, light traveling through air angles its path upon entering water. That's why objects underneath water appear distorted and offset. But light passes through the oil-quartz boundary without distortion, permitting the researchers to view flow around (and inside) complicated structures.

Lasers allow the researchers to measure fluid flow very close to a model's surface. "The laser light reflects off dust particles in the oil," explains INEEL researcher Don McEligot, a technical leader in Experimental Thermal Science. In wind tunnels, sensors attached to an object measure changes in fluid flow and often interfere with those measurements. But at the MIR facility, computer-controlled sensors outside the oil chamber pick up laser light reflections, and a computer recreates the flow pattern.

The goal is to model "realistic roughness." Turbine blades twirl behind the combustion chamber in a jet engine, converting the superheated, super-fast exhaust into propulsion. Over time, the blades lose their original smooth surface due to normal wear and tear. "They get deposits on them and cracks will form, eventually making a surface that looks like the surface of a golf ball," says Ralph Budwig, chair of the Department of Mechanical Engineering at the University of Idaho in Moscow. Perturbations in air flowing around the blades can decrease an engine's performance, and the pits and divots of realistic roughness produce such disturbances.

"It's difficult to characterize realistic roughness with mathematical equations," says Budwig, who specializes in developing techniques to measure velocity, temperature, and other conditions in fluid flows. Unlike the regular hills and valleys of a piece of sandpaper, the roughness on a turbine blade is random. Realistic roughness is as difficult to predict as random systems like the weather.

The MIR facility will allow University of Idaho doctoral student Hugh McIlroy to make detailed measurements of how roughness creates variations in flow. "The results of the research will improve performance and reduce maintenance costs," says McIlroy. This includes ways to determine the best time to replace the blades.

The team will also examine the blade's heat transfer properties. The air streaming out of a jet engine's combustion chamber is hotter than the blade's melting temperature, so turbine blades must be cooled internally. Understanding how the surface roughness affects the blade's ability to resist these high-temperature gases is a step towards improved performance. "We're among the first to use fluid flow to understand the effects of realistic roughness," says UI's Budwig.

The grant is part of a Department of Defense program to encourage competitive research in less-populated states. Currently, 17 states are eligible for the program, known as the Department of Defense Experimental Program to Stimulate Competitive Research, or DEPSCoR. Budwig will receive approximately $315,000 over three years, part of which funds Mackelroy's dissertation research.

The INEEL is a science-based, applied engineering national laboratory dedicated to supporting the U.S. Department of Energy's missions in environment, energy, science and national defense. The INEEL is operated for the DOE by Bechtel BWXT Idaho, LLC, in partnership with the Inland Northwest Research Alliance.
Media contacts:
Becky Oskin

Deborah Hill

Mary Beckman

Editor's note: For more information on the DEPSCoR programs, visit

For more information on the Matched Index of Refraction facility, visit

Visit our website at

DOE/Idaho National Laboratory

Related Mechanical Engineering Articles from Brightsurf:

Best practices for mechanical ventilation in patients with ARDS, COVID-19
A team from pulmonary and critical care medicine at Michigan Medicine outlines 20 evidence-based practices shown to reduce time spent on a ventilator and death in patients with acute respiratory failure and acute respiratory distress -- conditions that have many overlaps with severe COVID-19.

How cells use mechanical tension sensors to interact with their environment
In a painstaking experiment, scientists suspended a single protein filament between two microscopic beads.

Mechanical forces of biofilms could play role in infections
Studying bacterial biofilms, EPFL scientists have discovered that mechanical forces within them are sufficient to deform the soft material they grow on, e.g. biological tissues, suggesting a ''mechanical'' mode of bacterial infection.

How mechanical forces nudge tumors toward malignancy
Researchers studying two forms of skin cancer identified a long-overlooked factor determining why some tumors are more likely to metastasize than others: the physical properties of the tissue in which the cancer originates.

Building mechanical memory boards using origami
Origami can be used to create mechanical, binary switches, and in Applied Physics Letters, researchers report the fabrication of such a paper device, using the Kresling pattern, that can act as a mechanical switch.

Not just light: The sensitivity of photoreceptors to mechanical stimuli is unveiled
''We thought we knew almost everything about photoreceptors, but we have proved that is not the case''.

A mechanical way to stimulate neurons
Magnetic nanodiscs can be activated by an external magnetic field, providing a research tool for studying neural responses.

Cell removal as the result of a mechanical instability
Researchers at Kanazawa University report in the Biophysical Journal that the process of cell removal from an epithelial layer follows from an inherent mechanical instability.

Researchers demonstrate transport of mechanical energy, even through damaged pathways
Researchers from the University of Illinois at Urbana-Champaign's Grainger College of Engineering have experimentally demonstrated a new way to transport energy even through wave-guides that are defective, and even if the disorder is a transient phenomenon in time.

Tissues protect their DNA under mechanical stress
Nuclei and genetic material deform.

Read More: Mechanical Engineering News and Mechanical Engineering Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to