This technology could make Chinese submarines virtually undetectable
What's the story
A research team from China's Shanghai Jiao Tong University has developed a groundbreaking technology that could drastically enhance submarine stealth capabilities.
The study, published in the Chinese journal Noise and Vibration Control, suggests this innovation could theoretically reduce the detection range of enemy sonar systems by over 50%.
The team's work was led by Zhang Zhiyi at the university's State Key Laboratory of Mechanical Systems and Vibration.
Innovation
Reducing engine noise by 26dB
The new technology seeks to replace traditional rigid engine mounts with a hybrid active-passive vibration isolation system.
This system could cut down the engine noise transmitted via submarine hulls by as much as 26dB.
The innovative design uses a steel-rubber-steel "sandwich" ring for vibration dissipation, and an active layer with 12 piezoelectric actuators that are arranged radially around the engine to further minimize noise.
Functionality
What do piezoelectric actuators do?
The electrically-powered piezoelectric actuators in the new system, can neutralize the engine's micron-level movements with strong control forces through precision lever mechanisms.
The study notes that even a 10dB reduction in underwater vehicle noise can reduce its detectable range by as much as 32%.
This is because sound from power equipment operation is the primary noise source for underwater vehicles during low-speed navigation, and serve as their key acoustic signature for detection.
Operation
A look at the test
Zhang's team performed lab tests on a scaled-down prototype. It showed great performance with a 24dB reduction (12dB passive plus 12dB active) at 100Hz, and also 26dB at 400Hz.
The effective bandwidth was across 10-500Hz, and covered most engine harmonics.
The researchers said that noise cancellation in real-time was possible because of the system's very short response time.