Real-time monitoring shows current vessel status, while simulations predict future behavior.
|
Getting your Trinity Audio player ready...
|
Click to view glossary
Real-time monitoring can tell vessel operators what is happening at any given moment. Simulations, on the other hand, can help us understand and predict what might happen in the future.
The CLUE project also developed and tested a digital twin for the Azipod® propulsion system by placing accelerometers inside the pods and inputting the data into a mathematical model. A digital twin is a virtual replica of a physical system or object designed to mimic the performance of its real-world counterpart in a virtual environment. By creating a highly accurate model, engineers and operators can monitor, simulate, and predict the outcomes of different scenarios, such as design or operational changes. The CLUE digital twin was used to measure electromagnetic excitation and predict underwater radiated noise. The team created a new term for the noise emitted by electric components – magnetic underwater radiated noise. Including a digital twin in the CLUE project provided proof of concept – that a digital twin, fed with data in real time, is a viable way of estimating magnetic underwater radiated noise.
The HyPNoS project created a noise simulator using computational fluid dynamics. This technique uses mathematical equations that describe how fluids move and computers to simulate how liquids (like water) and gases (like air) move. The HyPNoS project showed how these simulations can capture many of the mechanisms that are thought to generate underwater radiated noise, such as how water pushed out from a propeller can interact with different points of a rudder and generate noise. With this information, engineers can design quieter vessel components for an overall quieter ship design. Quieter design is discussed in more detail in the article: Quieter design for ships: new-build and retrofit options.
Future direction: a call for more data
Whether detecting underwater radiated noise using acoustic ranges or onboard sensors, both methods require extensive and frequent measurements to ensure accurate, reliable data and to capture the variability in noise emissions over time and in different operating conditions. These QVI-funded projects demonstrate how different locations, different environments (e.g., shallow water versus deep, near shore versus open water), vessel types, seasons, and weather and oceanographic conditions can influence underwater noise.
The advantage of onboard sensors is continual measurement, and measurements less affected by changing environmental conditions—such as temperature, wind, rain, currents, sea ice, or depth. However, the algorithms that convert these measurements into estimates of underwater radiated noise are still sensitive to those same environmental factors.
Additionally, ship design plays a crucial role in underwater noise. An algorithm built using data from only one type of vessel or a single location and season may not be able to accurately estimate underwater radiated noise for other vessel types or in different environments and conditions. More broadly applicable and accurate algorithms require a broader range of data.
This article is part of a five articles series on technology for detecting and analysing underwater vessel noise.
Continue learning about the new discoveries and challenges in making vessels quieter with the other topics in this series here
The Quiet Vessel Initiative is a federally funded program through Transport Canada. Industry partners and researchers interested in potential research and development collaborations to advance innovative solutions in marine technology are invited to contact the Quiet Vessel Initiative team at Marine-RDD-maritime@tc.gc.ca.
Featured image credit: Ian Simmonds via Unsplash
Underwater noise: sound generated below water by human activity in the ocean environment. Various industries contribute to underwater noise—offshore energy, construction, military operations, and of course vessel traffic. The noise generated by vessels is referred to as underwater radiated noise.
Digital twin: a virtual replica of a physical system or object designed to mimic the behaviour and performance of its real-world counterpart in a virtual environment. By creating a highly accurate model, digital twins allow engineers and operators to monitor, simulate, and predict the outcomes of different scenarios, such as operational or design changes.
Azimuth propulsion system or Azipod®: a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder redundant. These give ships better maneuverability than a fixed propeller and rudder system. An Azipod® is essentially an azimuth thruster where the electric drive motor is contained inside the pod itself, beneath the water surface.
Accelerometer: a device that measures the vibration, or acceleration of motion, of a structure. The force caused by vibration or a change in motion (acceleration) causes the mass to “squeeze” the piezoelectric material which produces an electrical charge that is proportional to the force exerted upon it. Since the charge is proportional to the force, and the mass is constant, then the charge is also proportional to the acceleration. These sensors are used in a variety of ways – from space stations to handheld devices like smartphones.
Computational Fluid Dynamics: CFD uses computers and the equations of mass, momentum (or mass times velocity), and energy to predict the flow of liquids and gases. We are surrounded by liquids and gases, like air and water, and being able to analyze, understand, and predict the behaviour of these fluids allows us to understand the effects of fluid flow on a product or system.
