Cast Iron Air Pump,High Pressure Head,Air Compressor Head Guangda Electromechanical Co., Ltd. , http://www.tbcpower.com
The Doppler velocimeter is very useful for ships entering and leaving the port. It can accurately and conveniently measure the speed of the ship. A typical marine speedometer can only measure the speed between the ship and the sea, but not the relative speed of the ship and the sea floor. Since the sea water moves with the wind and waves, sometimes even if the speed of the ship is small, when the wind is very strong, the speed of the ship relative to the sea floor is still very large, which causes great difficulty for the ship to be docked. The general large-scale 10,000-ton wheel speed is strictly required. The large-scale 10,000-ton wheel has a large hull and a strong inertia. The speed at the time of docking or anchoring must be very low. Usually required to be less than 0.1 ~ 0.3 knots, that is, less than 1 m / min, so it is very important to accurately measure the speed of the ship to the seabed.
The Doppler navigation sonar made by the Doppler effect can accurately measure the ship's ground speed, and the accuracy reaches 0.01 knots, which fully meets the ship landing requirements. The transducer of the Doppler navigation sonar is placed in the front half of the bottom of the ship, allowing it to emit a narrow beam obliquely forward or obliquely rearward. Since the ship is driving forward, the echo frequency reflected from the undulating sea floor will have a certain offset.
According to the frequency shift measured by the speedometer, the ground speed of the ship sailing can be obtained. Sometimes to reduce the ship's sway and the difference in echo frequency shift on the seafloor, the sound waves can be emitted in the four directions at the bottom of the ship, so that the accurate ground speed of the ship can be measured. The captain can control the direction and speed of the ship according to the speed condition of the hull sailing to ensure that the ship, especially the large ship, can only be safely docked.