China claims classified system reduces submarine noise by 90% making them more stealth and powerful

The new design could increase the thrust of a pump-jet at slower speeds while significantly reducing the noisy vibration “at most characteristic frequencies,” said Hua Hongxing, the research lead, and professor of the State Key Laboratory of Mechanical System and Vibration at Shanghai Jiao Tong University, who conducted simulation experiments at a ground testing facility. A shrouded propeller, which encloses the rotor in a duct to produce a water jet for propulsion, is sometimes utilized by modern submarines. The distance between the rotor blades and the inner wall of the duct can be as little as one millimeter. Yet, it…