| 摘要 |
PURPOSE:To grasp the speed and direction of a tidal current in three dimensions by emitting ultrasonic wave beams in four front and rear, and left and right directions of a ship at adequate angles to the surface of water, and then obtaining speed information. CONSTITUTION:Ultrasonic wave beams are sent to the front and rear of a ship S at a standstill in directions OA0 and OB0 at optional angle alpha. For the measurement of a tidal current which has a velocity V0 and an angle phi0 to an Y axis, the velocity V0 is found from speed components VA and VB in directions OA0 and OB0 of an ultrasonic flow meter. The components of the velocity V0 are as shown in the figure. Similarly, the speed component VX in the left and right (X axis) direction of the ship is found by using two beams in the left and right direction, so the velocity V0 and phi0 of the tidal current or the azimuth of the V0 projected on an XY plane is also found from the found VX, YY, and VZ. |
