China would have achieved An important advance in underwater navigation that could advance to its fleet in front of that of other powers in a fundamental aspect, The stealth. A team of scientists has developed an active-pepher-pepher of vibration insulation system for engines that would considerably reduce the acoustic firm of submarines, reports South China Morning Post.
According to the investigation, conducted by ZHANG ZHIYI And his team of the Jiao Tong University of Shanghai with the support of the China State Shipbuilding Corporationthis new vibration cushion system could reduce the noise of submarines in up to 50 %making them much more difficult to detect.
A two -layer system
The system consists of two layers, one passive and an active one. The passive layer uses a series of steel-gum-steel sandwich rings that absorb vibrationsa significant improvement with respect to traditional rigid motor supports found in most submarines.
The active layer incorporates some Twelve piezoelectric actuators -Dispositive that convert an electrical signal into mechanical force- distributed around the engine, capable of Counter in real time the vibrations of the motor at the micrometric levelthrough intense control forces applied through precision lever mechanisms.
So silent as to get confused in the marine background noise
According to the equipment, both layers can reduce engine noise in Up to 26 decibels (DB). A 10 dB reduction can reduce the range of sounding in approximately 32 %; Therefore, a 26 dB reduction could do it less than half. This mainly affects low frequency tonal noise, the main road of underwater detection by sounding.
As a reference, American modern submarines have acoustic firms that range between the 90 dB (Ohio class) and the 130 dB (Los Angeles class, older). He habitual marine noiseproduced by waves, marine fauna and other ships, varies between 85 and 95 dB. Therefore, reducing noise to similar levels allows a submarine to hide in noise ‘.
‘During low -speed navigation, The mechanical noise generated by the propulsion equipment constitutes the main noise source Of the submarine vehicles and their most relevant acoustic firm, usually in the form of low frequency tonal components, ‘explain the researchers. ‘Implement vibration cushion measures that Limit energy transmission from engines through support structures is key To improve the acoustic stealth of underwater vehicles, ‘they add.
Cancellation of noise in real time using an algorithm
In tests with a scale model, the new system managed to reduce 24 dB at 100 Hz (12 dB through the passive layer and another 12 dB with the active) and 26 dB at 400 Hz. According to the study, the system has an effective bandwidth 10 to 500 Hzcovering most of the typical engine sounds. In addition, real noise cancellation was possible thanks to an extremely short response time.
The system also includes a FX-LMS adaptive algorithm (Filled-X Least Mean Squares) for Real control the 12 actuators without generating instabilitya usual problem in feedback systems.
Despite the potential, the authors warn that performance could degrade in the face of temperature and pressure changes in the marine environment, especially due to the sensitivity of rubber to these variations.
The durability of piezoelectric materials in real conditions of prolonged use in submarines is also unknown. SCMP does not confirm whether this technology will be integrated soon in Chinese Operating Submarines. If it is demonstrated effective and finally it was the case, The stealth capabilities of Chinese submarines would increase very significantly.