Tech Briefs Magazine - July 2021 - 20

Aeronautics
Method Detects Onset of Destructive Oscillations in
Aircraft Turbines
Early flutter detection will help in the development of safer and more eco-friendly
aircraft turbines.
Tokyo University of Science, Japan
lutter is a complex oscillatory phenomenon
that can destroy aircraft
turbine blades and has historically been
the cause of several plane accidents. In
aerospace research, flutter generally
refers to undesired and self-sustained vi -
brations in turbine blades that can readily
grow out of control, destroying them
along with the engine and even the aircraft's
wings.
Researchers have developed an ap -
proach that can be used for early detection
of the onset of flutter, solving one of
the main problems that has been holding
back the design of lighter and more
efficient turbines. The main idea behind
the approach is that the turbine fan can
be mathematically modeled as a complex
network of interrelated oscillators
F
and that flutter is ultimately the result of
the progressive synchronization of more
and more blades as a result of increased
airflow going through the turbine.
Through experiments on a turbine
test rig, the team found that before the
onset of flutter, one particular blade
begins to act as a " central hub " in the
network and adjacent blades start to
oscillate in sync with it. This " local " synchronization
quickly expands and leads
to the collective synchronization of all
blades, resulting in potentially catastrophic
flutter.
In this context, the network representation
of the system demonstrated the
applicability of two local and global
measures as potential detectors of cascade
flutter: the connecting strength
Insect-Sized Agile Drones
These tiny aerial robots can operate in cramped spaces and withstand collisions.
Massachusetts Institute of Technology, Cambridge
nsects can be remarkably acrobatic
and resilient in flight. Those traits
help them navigate the aerial world,
with wind gusts, obstacles, and general
uncertainty. Researchers have developed
insect-sized drones with similar
dexterity and resilience. The aerial
robots are powered by a new class of
soft actuator that allows them to withstand
the physical travails of real-world
flight. The robots could one day aid
humans by pollinating crops or performing
machinery inspections in
cramped spaces.
Typically, drones require wide open
spaces because they're neither nimble
enough to navigate confined spaces nor
robust enough to withstand collisions in
a crowd. Very small drones require a fundamentally
different construction than
larger ones. Large drones are usually
powered by motors, which lose efficienI
20
Cov
between
individual network nodes and
the network's synchronization parameter.
The former is valid for specifying the
dominant blades for the onset of cascade
flutter. In contrast, the latter, which
ranges from 0 to 1, is more suitable for
determining a threshold for this onset.
The combined findings shed light on
the complex phenomenon of flutter and
contribute to the academic systemization
of nonlinear problems in the field
of aeronautical engineering and related
nonlinear science. They could represent
promising techniques
for
the
early
detection of flutter onset in the design
state of blades.
For more information, contact the Science
Public Relations Office at mediaoffice@
admin.tus.ac.jp.
Insects' remarkable acrobatic traits help them navigate the aerial world, with all of its wind gusts,
obstacles, and general uncertainty. Such traits are hard to build into flying robots; however, the
new drone system approaches insects' agility. (Image: Courtesy of Kevin Yufeng Chen)
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Tech Briefs, July 2021
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Tech Briefs Magazine - July 2021

Table of Contents for the Digital Edition of Tech Briefs Magazine - July 2021

Tech Briefs Magazine - July 2021 - Intro
Tech Briefs Magazine - July 2021 - Sponsor
Tech Briefs Magazine - July 2021 - Cov1
Tech Briefs Magazine - July 2021 - Cov2
Tech Briefs Magazine - July 2021 - 1
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