Beijing. The nuclear-powered submarines of the US Navy are considered to be one of the world's most stealthy war machines. But with advances in submarine-detection technology, Chinese scientists claim that they can now detect even the quietest nuclear submarines. Researchers at Northwestern Polytechnical University (NPU) in Xi'an claim that they can now detect even the quietest submarines using the magnetic fields generated by the submarines. These magnetic fields are formed due to the intricate and turbulent flow fields generated by the movement of submarines. According to a report in Hong Kong-based South China Morning Post, this new technology could revolutionize naval warfare.
The team, led by Assistant Professor Wang Honglei, modeled the Kelvin wake, a V-shaped surface disturbance created by submarines moving through water. “This wake has previously been studied for radar-based imagery detection, but when the ions in seawater – which are affected by the submarine’s motion – interact with the Earth’s geomagnetic field, it generates a faint but detectable magnetic field,” the report said.
The researchers used computer simulations to measure the changes in these magnetic variations with the size, depth, and speed of the submarine. “For example, increasing the speed by 2.5 meters per second (8.2 feet per second) increases the magnetic intensity tenfold; decreasing the depth by 20 meters (66 feet) doubles the field strength,” they said. And longer submarines produce weaker fields, while wider hulls amplify them.
According to Wang and his colleagues, a Seawolf-class submarine traveling at a speed of 24 knots (12.5 meters per second) and a depth of 30 meters (98 feet) can have a magnetic field in its wake that reaches 10-10² Tesla. This is “within the sensitivity range of existing airborne magnetometers.” In the study, published December 4 in the peer-reviewed journal of Harbin Engineering University, the team exploited a key loophole: “The Kelvin wake cannot be silenced.” The paper specifically studied Seawolf-class submarines. Interestingly, last October, the US Navy’s nuclear-armed fast-attack submarine, the USS Seawolf, was spotted in Yokosuka, Japan, which is close to China.
Seawolf-class submarines are considered to be one of the US Navy's most powerful, lethal, complex, and expensive underwater combat platforms, designed for high-level missions near the enemy's coast. They are also known as "silent killers" because they can go to depths and pursue targets for months.
Seawolf-class submarines are equipped with a large number of Tomahawk missiles and torpedoes, which can pose a serious threat to China's coastal infrastructure and the PLA Navy. A Seawolf-class submarine - USS Connecticut - collided with an underwater mountain in the disputed South China Sea in October 2021. Since the submarine was on a secret mission, its condition was not known. China was stunned by this incident.
