The Ekman current meter is a mechanical flowmeter created by Vagn Walfrid Ekman, a Swedish marine expert, in 1903. It consists of a propeller with a mechanism for recording the number of revolutions, compasses and recorders used to record directions , and propellers that direct the instrument so that the blades are facing the current. It is mounted on a free swinging axis vertically suspended from the wire and has the weight attached below.
Balanced propellers, with four to eight blades, rotate inside a protective ring. The lever position controls the propeller. In the downpour position is stopped and the instrument is lowered, after reaching the desired depth, a load called messenger is lowered to move the lever to the middle position allowing the propeller to rotate freely. When the measurements have been taken, the other weight is dropped to push the level to the highest position where the back propeller stops.
The revolution of the propeller is calculated through a simple mechanism that lowers the revolution and counts it on the indicator button. The direction is shown by devices connected to the directional blades that drop a small metal ball about every 100 turns. The ball falls into one of the thirty-six compartments at the bottom of the compass case indicating the direction of a multiple of 10 degrees. If the direction changes when the measurement is made, the ball will fall into a separate compartment and the weighted average is taken to determine the direction of the average current.
It is a simple and reliable instrument whose main losses are those that must be drawn to read and reset after each measurement. Ekman solves this problem by designing a repeatable flow meter that can reach forty-seven measurements before it needs to be transported and reset. This device uses a more complicated system to drop the small numbered metal ball periodically to record separate measurements.
Video Ekman current meter
Bibliography
H. U. Sverdrup, Martin W. Johnson, and Richard H. Fleming: Oceans: Physics, Chemistry, and Their General Biology. publisher Prentice-Hall , Inc., 1942.
Maps Ekman current meter
See also
- Ocean currents
- Ekman spiral
- the water bottle Ekman
Source of the article : Wikipedia
0 Comments