Han Ru Liu & Xinyue Guo
Age 17 & 18 | Montreal, Quebec
Scientific Pursuits Award
Designed to protect marine life and to reduce the amount of noise and pollution produced by motorized propellers, this research focuses on the creation of a magnetohydrodynamic propulsion system. It uses the notion of magnetohydrodynamics (MHD), which studies the behaviour of electrically conductive fluids when subjected to a magnetic field. This system is powered by the Lorentz force, the perpendicular combination of electric and magnetic forces. In order to investigate the possibility of using MHD systems as a large-scale application, this design was tested on a small-scale. The use of lead electrodes, neodymium magnets, copper wires and some other materials helped achieve this. Despite the infrequent occurrence of a few sources of errors, this system was able to successfully produce a Lorentz force of 0.190 N. Thus, the application of magnetohydrodynamic propulsion systems on a large-scale can be feasible. We hope this system may be used in the future to replace motorized propellers in ships.
INTRODUCTION
Often called the heart of the planet, the oceans are an essential component of Earth’s ecosystem. More than 50% of the oxygen humans breathe is produced by oceans, and they store 50 times more CO2 than the atmosphere. Oceans also provide us with convenient shipping routes. Ships transport everything from food to construction equipment and account for 90% of all trade between countries (ICS, n.d.). This raises the question of “how do ships affect water and air quality?” Answer: negatively. A study from the Wisconsin Department of Natural Resources determined that ships can add metals, harmful chemicals, unburned gas, and oil mixtures into the water (RMBEL, 2013). These negative effects are mainly caused by motorized propellers. Therefore, the focus of this research is to protect marine life and to reduce the amount of pollution created by motorized propellers. To achieve this goal, the researchers propose a different propulsion system, one that uses the concept of MHD. MHD is a technology that mainly focuses on how conductive fluids, such as seawater, behave when subjected to magnetic and electrical fields. It uses the Lorentz force, a combination of electric and magnetic forces. The presence of magnetic fields leads to forces that in turn act on the fluid. The forces thereby potentially alter the direction and strength of the magnetic fields themselves. The mathematical equation for finding the Lorentz force can be expressed as:
F=IL x B
In this equation, F represents the Lorentz force (Newton), I represents the flow of the current (Ampere), L represents the length along which the current acts (meter) and B represents the magnetic force (Tesla). With the length L as a constant in which the current travels, the relationship among F, I and B is a direct variation. If a magnetic field and an electric field can cause a Lorentz force to a fluid such as seawater, then a magnetohydrodynamic motor could be designed as a new propulsion system for ships.
MATERIALS
A 0.150 m plastic tube as the body of the magnetohydrodynamic propulsion system. To create the Lorentz force required to propel the ship, two lead electrode strips and four neodymium magnets were used. In order to create an electrical field, copper wires, alligator wires and a power supply are also needed. The magnets are completely wrapped in aluminum foil and secured to the plastic tube with packing tape. This will generate a magnetic field. Table salt and a plastic container, one large enough to hold the MHD propulsion system, were used to represent sea water.
PROCEDURE
In order to construct the magnetohydrodynamic propulsion system, two holes were drilled in each electrode, one on the left and one on the right. Repeat the previous step on opposite sides of the plastic tube, aligned with the ones in both electrodes. Then, 30 cm of the copper wire was connected into each hole of the electrode. By pulling the copper wires through the holes in the tube, the electrodes were connected to the plastic tube. Next, in order to ensure secure placement of the electrodes, the copper wires were twisted together. To block the permeation of saltwater, each neodymium magnet was wrapped in aluminum foil. Afterwards, place the magnets on the tube, two on each side. The packing tape was used to secure the magnets on the plastic tube. Thereafter, connect the copper wires of one electrode to an alligator wire and the copper wires of the other electrode to another alligator wire. After that, clip the alligator wires to the power supply. Plug in the power and turn it on to 2.1A. Water and table salt were added into the plastic container. Finally, place the MHD propulsion system in the water and watch the water be pushed out.
DATA & RESULTS
Table 1: The Lorentz force generated by an MHD system.
Figure 1: Finding the Lorentz force of the magnetohydrodynamic propulsion system.
Figure 2: MHD propulsion system.
DISCUSSION
A Lorentz force of 0.190N was successfully produced (See Figure 1 and Table 1). The four neodymium magnets, taped on op- posite sides of the plastic tube, generated a magnetic force of 0.6024T. Individually, one neodymium magnet has a magnetic field strength of 0.1506T. On the other opposite sides of the plastic tube, two lead electrode strips were attached tightly on the inside of the tube with copper wires (See Figure 2). These copper wires were then connected to a power supply with a current of 2.10A (See Figure 1). Following this, a spout of seawater was immediately pushed out of the plastic tube. There were a few sources of error that occurred with this design. Although the salinity of the fluid is close to that of seawater, the conductivity of the fluid may still be influenced by the salinity. Moreover, the errors in the measurement of the magnetic force may alter the calculation of the Lorentz force. Lastly, due to the presence of hydrogen, the electrolysis of water may also affect the Lorentz force. The blueprint of this design is attached at the end of this report and it presents all the components of this magnetohydrodynamic propulsion system (see Figure 2).
For future directions of study, the researchers would test the system with different sized boats to see how feasible it would be if this were used to replace motorized propellers on ships on a large scale. Additionally, to achieve the goal of eliminating any obstacle that could impede with the MHD system’s performance, a covering would be attached at the opening of the system which allows the passage of water, but prevents the passage of any other object (rocks, plastics, etc.).
CONCLUSION
In conclusion, it can be said that a magnetohydrodynamic motor was successfully demonstrated on a small scale. Although it is still unclear whether this system can be successfully used as a propulsion system for ships, the model were able to generate 0.190N of Lorentz force with 2.10A of current and 0.6024T of magnetic force in a 0.125m plastic pipe. In order for this system to be used in larger operations, a stronger current, a more intense magnetic field, and a longer insulated pipe must be considered. Issues that come with magnetohydrodynamic motors include: the buoyancy force must be great enough that it can float the weight of the motor and the ship and there can be electrolysis of water. To prevent potential safety problems, the hydrogen gas created by the electrolysis of water must be contained or collected, and the insulation must be done meticulously.
BIBLIOGRAPHY
Boat Motors and Water Quality. (2015, May 11). Retrieved from https://www. rmbel.info/boat-motors-and-water-quality/.
Dorch, S. B. F. (n.d.). Magnetohydrodynamics. Retrieved from http://www.schol- arpedia.org/article/Magnetohydrodynamics.
Neiser, T. and Sutcliffe, W. (2009, June 19). Report on MHD Propulsion [PDF file]. Retrieved from https://www.dropbox.com/s/vx78m2quhsedhxp/Report%20on%20MHD%20Propulsion.pdf.
Open ocean: importance. (n.d.). Retrieved from https://wwf.panda.org/our_work/ oceans/open_ocean/ocean_importance/.
Santiago, E.D. (n.d). How Much Fuel Does A Cruise Ship Use? Retrieved from https://cruises.lovetoknow.com/wiki/How_Much_Fuel_Does_a_Cruise_ Ship_Use
Shipping and World Trade. (n.d.). Retrieved from https://www.ics-shipping.org/shipping-facts/shipping-and-world-trade.
US Department of Commerce, & National Oceanic and Atmospheric Administration. (2017, May 24). Why should we care about the ocean? Retrieved from https://oceanservice.noaa.gov/facts/why-care-about-ocean.html
ABOUT THE AUTHORS
Han Ru Liu
My name is Han Ru Liu and I’m a 17-year old Chinese-Canadian student who lives in Montreal, Quebec. I completed my high school education at Miss Edgar’s and Miss Cramp’s School and am currently studying Pure and Applied Sciences at Marianopolis College. From a young age, I’ve been interested in all things related to science and technology. In addition, I’ve always fostered a fascination for the power and beauty of nature. I’m an avid pianist and saxophone player who has a passion for protecting the environment and exploring the unknown. I love to volunteer, challenge myself, learn new skills and participate in outdoor adventures, allowing me to earn my Bronze and Silver Duke of Edinburgh award. In my spare time, I enjoy creating acrylic pour paintings, cooking, singing and reading autobiographies and memoirs.
Xinyue Guo
I am Xinyue Guo and am an international student currently studying Honours Health Science at Marianopolis College in Montreal, Canada. Just like Ralph Waldo Emerson once said, “men love to wonder, and that is the seed of science.” Science to me is life-changing, as it stimulates my interest in looking at the world from a brand new perspective. I am always excited to explore more about the scientific field and to contribute my efforts to the world of science. I have a great passion for learning new things and challenge myself, and I believe that learning should be a never-ending process. With my curiosity and perseverance, I won the scientific pursuit award in my graduating year and ranked 16th worldwide in the Caribou Math Contest.