Serendipitous discovery could increase efficiency in jet engines, reduce plane noise, more
A group of new smart materials discovered by researchers at Texas A&M University and their colleagues has the potential to significantly improve the efficiency of fuel burn in jet engines, cutting the cost of flying. The materials, which could also reduce airplane noise over residential areas, have additional applications in a variety of other industries.
"What excites me is that we have just scratched the surface of something new that could not only open a completely new field of scientific research, but also enable new technologies," said Dr. Ibrahim Karaman, Chevron Professor I and head of the university's Department of Materials Science and Engineering.
The work was published in Scripta Materialia. Karaman's co-authors are Demircan Canadinc, William Trehern, and Ji Ma of Texas A&M, and Fanping Sun and Zaffir Chaudhry, Technical Fellow of the United Technologies Research Center (UTRC).
The discovery is based on bringing together two relatively new areas of materials science involving metal alloys, or metals composed of two or more elements. The first area involves shape-memory alloys, "smart" materials that can switch from one shape to another with specific triggers, in this case temperature. Picture a straight metal rod that is bent into a corkscrew. By changing the temperature, the corkscrew turns back into a rod and vice versa.
Many potential applications for shape-memory alloys involve extremely hot environments like a working jet engine. Until now, however, economical high-temperature shape memory alloys, (HTSMAs), have only worked at temperatures up to about 400 degrees Celsius. Adding elements like gold or platinum can significantly increase that temperature, but the resulting materials are much too expensive, among other limitations.
Karaman, while working on a NASA project with UTRC and colleagues, began this research to address a specific problem: controlling the clearance, or space, between turbine blades and the turbine case in a jet engine. A jet engine is most fuel-efficient when the gap between the turbine blades and the case is minimized.
However, this clearance has to have a fair margin to deal with peculiar operating conditions. HTSMAs incorporated into the turbine case could allow the maintenance of the minimum clearance across all flight regimes, thereby improving thrust specific fuel consumption.
Another important potential application of HTSMAs is the reduction of noise from airplanes as they come in to an airport. Planes with larger exhaust nozzles are quieter, but less efficient in the air. HTSMAs could automatically change the size of the core exhaust nozzle depending on whether the plane is in flight or is landing.
Such a change, triggered by the temperatures associated with these modes of operation, could allow both more efficient operation while in the air and quieter conditions at touchdown.
Karaman and his colleagues decided to try increasing the operating temperatures of HTSMAs by applying principles from another new class of materials, high-entropy alloys, which are composed of four or more elements mixed together in roughly equal amounts.
The team created materials composed of four or more elements known to form shape-memory alloys (nickel, titanium, hafnium, zirconium and palladium), but purposefully omitted gold or platinum.
"When we mixed these elements in equal proportions we found that the resulting materials could work at temperatures well over 500 degrees C--one worked at 700 degrees C--without gold or platinum. That's a discovery," said Karaman. "It was also unexpected because the literature suggested otherwise."
How do the new materials work? Karaman said they have ideas on how they operate at such high temperatures, but do not have solid theories yet. To that end, future work includes trying to understand what is happening at the atomic scale by conducting computer simulations.
The researchers also aim to explore ways to improve the materials' properties even further. Karaman notes, however, that many other questions remain.
"That's why I believe this could open a completely new area of research," he said. "While we will continue our own efforts, we are excited that others will now join us so that together we can push the boundaries of science."
This joint project between UTRC and Texas A&M was funded by the NASA Leading Edge Aeronautics Research initiative.
Aubrey Bloom | EurekAlert!
Graphene-based actuator swarm enables programmable deformation
02.04.2020 | Science China Press
How to remove dirt easily
02.04.2020 | Max-Planck-Institut für Polymerforschung
90 million-year-old forest soil provides unexpected evidence for exceptionally warm climate near the South Pole in the Cretaceous
An international team of researchers led by geoscientists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) have now...
The bacteria that cause tuberculosis need iron to survive. Researchers at the University of Zurich have now solved the first detailed structure of the transport protein responsible for the iron supply. When the iron transport into the bacteria is inhibited, the pathogen can no longer grow. This opens novel ways to develop targeted tuberculosis drugs.
One of the most devastating pathogens that lives inside human cells is Mycobacterium tuberculosis, the bacillus that causes tuberculosis. According to the...
An international team with the participation of Prof. Dr. Michael Kues from the Cluster of Excellence PhoenixD at Leibniz University Hannover has developed a new method for generating quantum-entangled photons in a spectral range of light that was previously inaccessible. The discovery can make the encryption of satellite-based communications much more secure in the future.
A 15-member research team from the UK, Germany and Japan has developed a new method for generating and detecting quantum-entangled photons at a wavelength of...
Together with their colleagues from the University of Würzburg, physicists from the group of Professor Alexander Szameit at the University of Rostock have devised a “funnel” for photons. Their discovery was recently published in the renowned journal Science and holds great promise for novel ultra-sensitive detectors as well as innovative applications in telecommunications and information processing.
The quantum-optical properties of light and its interaction with matter has fascinated the Rostock professor Alexander Szameit since College.
Researchers at the University of Zurich show that different stem cell populations are innervated in distinct ways. Innervation may therefore be crucial for proper tissue regeneration. They also demonstrate that cancer stem cells likewise establish contacts with nerves. Targeting tumour innervation could thus lead to new cancer therapies.
Stem cells can generate a variety of specific tissues and are increasingly used for clinical applications such as the replacement of bone or cartilage....
02.04.2020 | Event News
26.03.2020 | Event News
23.03.2020 | Event News
02.04.2020 | Physics and Astronomy
02.04.2020 | Information Technology
02.04.2020 | Health and Medicine