Water Fountain 5 (Heron’s Fountain)

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Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• When a vinyl tube is used to flow water in the bucket downward, water spouts from the PET bottle on the left. However, there isn’t much difference in water levels between the bucket and the PET bottle.
• This experiment uses the principle of Heron’s fountain. The siphon principle is used to cause water in the bucket on the right to flow downward. As the water continues to flow along the path, it arrives at the PET bottle, which is filled with air, and as the bottle fills with water, the air inside is compressed, resulting in an increase in air pressure. Another vinyl tube is connected to this PET bottle, and air flows upward through this tube. The upper end of this tube is connected to another PET bottle (top left) for spouting water. Air flowing from the down fills this second bottle, thereby increasing the internal pressure. As a result, water spouts from the PET bottle on the upper left.
• The height A of the water fountain is considerably higher than the level of the water in the bucket on the upstream side. The energy source for this height is the difference in water levels between the bucket and the lower PET bottle (height B). Because of height B, the pressure of the air inside the lower PET bottle increases. As a result, a pressure nearly equivalent to this pressure acts on the air and water inside the PET bottle on the upper left side. In other words, the water spout is generated by height B. Height A of the water fountain generated is smaller than height B, and the difference between them corresponds to energy losses generated inside the vinyl tube. Height A of the water fountain is lower than height B by the amount of energy losses. However, if height B is increased, a taller water fountain can be generated.

[Keywords]	water depth, pressure, potential energy
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[Reference]	“The Wonders of Flow,” Japan Society of Mechanical Engineering, Kodansha Blue Backs, pp.38-41 and 98-101 “Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natume Publishing, pp.18-19 and 192-193