This article originally appeared on UBC News.
Long-term ship noise can cause stress, hearing loss and feeding problems for marine mammals such as whales, dolphins and porpoises. UBC Engineering researchers are diving in to help solve this issue.
According to project lead Dr. Rajiv Jaiman, an associate professor in the Department of Mechanical Engineering, propeller noise accounts for more acoustic barrages than ships.
“Propeller noise can be as high as 170 decibels, the equivalent of a jet engine or rocket lift-off,” Dr Jamon said.
popping and singing
The bubbles are the cause of the noise. The motion of the ship and the rotation of its propeller create bubbles of steam which then explode. This produces a popping effect and a high-pitched “singing” that can disturb crew and passengers and disrupt marine life within a 100 km radius.
To reduce noise, researchers are studying solutions such as injecting a jet of fluid to help control propeller movement or introducing wavy and serrated edges to break up noise-causing flow patterns .
Dr. Zaiman and his colleagues are also developing an artificial intelligence (AI) based framework to rapidly analyze the fluid interactions and dynamics behind the noise. They’re hoping to eventually provide marine engineers with a new suite of tools to design and build quieter propellers.
smart, lightweight framework
The team aims to improve other ship parts and systems through better structural components and materials that have the potential to reduce noise.
Project co-leader Dr. Jasmine Jelovica, a naval architect and assistant professor of mechanical and civil engineering in the Faculty of Applied Sciences, said the innovative material layout can reduce the weight of structural components by up to 50 percent. “Upgraded structures may be better noise barriers. They may be stronger and have other benefits as well.
He said some shipbuilders have started using sandwich panels made of metals and composites in the hulls of their ships. However, structural change can potentially affect safety and other aspects, so this type of change needs to be done gradually.
“The good news for us as researchers is that the marine industry is receptive to these innovations. They recognize the need for change and the need to become more sustainable and eco-friendly,” said Dr. Jelovica.
With funding support from the Natural Sciences and Engineering Research Council of Canada (NSERC), the researchers are working together with industry partners such as Seaspan Shipyards, Robert Allen Ltd. and Word Marine on this five-year project.
AI will help build green ships
AI and machine learning are a big part of the team’s work, enabling them to perform analysis and simulations in a fraction of the normal time.
“Modeling a ship using traditional computational methods takes time. Modeling even a small proposed structural change can take weeks. With AI, that work can be done in seconds,” Dr. Jelovica said.
The researchers recently received additional funding from Transport Canada’s Quiet Vessel Initiative to build a machine learning-based noise-prediction toolkit that would allow ships to adjust their noise based on the location of nearby marine mammals, and new AI software tools that can predict underwater shipwrecks. Noise at the beginning of the design phase.
“Skillful AI-based predictions combined with innovative flow control devices and structural modifications can help us tackle ship noise pollution while reducing carbon emissions,” said Dr. Zaiman.