JP4596999B2 - Control method of anti-vibration tank system - Google Patents

Description

  The present invention relates to a method of controlling a reduced water tank apparatus that suppresses rolling of a ship.

  In recent years, there have been many accidents in container ships, etc., in which a large number of containers are leaked or damaged, and one of the causes is thought to be the occurrence of rolling called parametric rolling (for example, Non-patent document 1).

  Parametric roll is a roll caused by a change in stability force coefficient, which is a parameter in the equation of roll motion, over time. The main factor that changes the stability coefficient with time is during longitudinal or transverse waves. In water line area second moment increases or decreases due to relative water level change.

  Parametric rolls themselves have been known for a long time, but in recent years, the possibility of parametric rolls has increased with the change in hull form that is being carried out in order to increase the loading capacity of container ships, etc. The impact of this is also increasing.

  On the other hand, conventionally, as a device for reducing the rolling of a ship, a pair of left and right wing tanks, a connecting water channel that communicates the lower part of the pair of left and right wing tanks, and an air duct that communicates the upper part of the pair of left and right wing tanks There is known an anti-vibration water tank device provided with an anti-vibration water tank having an air duct and a valve for switching between operation and non-operation of the anti-vibration water tank by opening and closing thereof. This anti-vibration water tank apparatus obtains an anti-vibration effect by utilizing the phase difference when the liquid in the anti-vibration water tank excited by the rolling of the ship moves.

Naoya Umeda, 1 other, “Chapter 3-2 Parametric roll”, Symposium of the Japan Shipbuilding Society / Test Tank Committee, December 2003, p. 217-236

  Normally, the shaking of the hull in the transverse wave occurs with a phase delay of 90 degrees with respect to the transverse wave. However, if the natural period of the dimming tank is matched with the rolling period of the hull, the movement of the liquid in the dimming tank will be As a result, a phase delay of 90 degrees occurs with respect to the rolling of the horizontal wave, and as a result, a phase delay of 180 degrees occurs with respect to the transverse wave. At this time, the roll moment caused by the transverse wave and the moment caused by the liquid in the reduced water tank are opposite to each other, and the roll moment acting on the hull is canceled out to obtain a reduction effect.

  However, the parametric roll is a phenomenon in which a large roll is rapidly generated and developed when the ratio of the pitch period to the natural roll period is approximately 1: 2. However, the conventional anti-vibration tank system controls the natural period of the anti-vibration tank so that it matches the roll period of the hull, and the ratio between the pitch period and roll natural period, which is the cause of parametric roll generation, is controlled. Is approximately 1: 2, no control is performed to prevent the development of parametric rolls, and an effective control effect for preventing the development of parametric rolls cannot be obtained. It was.

  The present invention has been made in view of the above circumstances, and a method for controlling a reduced water tank apparatus capable of preventing the occurrence and development of parametric rolls and obtaining a good rocking effect against parametric rolls. Is intended to provide.

  In the present invention, based on the idea that parametric roll occurs when the ratio between the pitch period and roll natural period of the hull is approximately 1: 2, the pitch period and roll natural period of the hull are based. When the ratio is 1: 2, the movement of the liquid in the anti-vibration tank is controlled with respect to the pitch angle of the hull, thereby suppressing parametric rolls and providing an appropriate anti-vibration effect. Standing from the perspective that it can be demonstrated.

  That is, the present invention has the following features in order to solve the above problems.

[1] A rocking water tank provided with a pair of wing tanks installed on the port side and the starboard side of a ship, a connecting water channel that communicates the lower part of the pair of wing tanks, and an air duct that communicates the upper part of the pair of wing tanks; The main body of the shaking water tank apparatus provided with the valve for switching the operation and stop of the vibration reducing water tank by opening and closing the air duct, and the roll angle data and the pitch angle output from the shaking detection means. In a reduced aquarium device comprising a reduced aquarium tank control device that determines the rolling natural pitch and pitch cycle of the hull based on the data and controls the opening and closing of the valve according to the pitch angle,
When the ratio of pitch period to roll natural period is about 1: 2, and the pitch angle is a nearly positive peak, if the roll angle takes alternating positive and negative peaks, the pitch angle is Close the valve near the moment when it changes from positive to negative, and open the valve near the moment when the pitch angle changes from negative to positive,
When the ratio of pitch period and roll natural period is approximately 1: 2, and the pitch angle is a nearly negative peak, if the roll angle is alternating between positive and negative peaks, the pitch angle is A control method for a rocking water tank apparatus, wherein the valve is closed in the vicinity of the moment when it shifts from negative to positive, and the valve is opened near the moment when the pitch angle changes from positive to negative.

  In the present invention, based on the idea that parametric rolls occur when the ratio of the pitch and roll periods of the hull is approximately 1: 2, the ratio of the pitch and roll natural periods of the hull is determined. When the ratio is approximately 1: 2, the phase of the horizontal movement of the liquid in the reduced water tank is performed with respect to the pitch angle of the hull so that a phase delay of 90 degrees occurs with respect to the roll angle. Since the operation / stop of the anti-vibration water tank is controlled, the parametric roll is suppressed and an appropriate anti-vibration effect can be exhibited.

  FIG. 1 is a diagram showing a reduced water tank apparatus used in an embodiment of the present invention. In the figure, the anti-vibration water tank apparatus used in one embodiment of the present invention is composed of an anti-vibration water tank apparatus main body 10 and an anti-vibration water tank control apparatus 20.

  The main body 10 for reducing water tank device is provided on the port side and starboard side of the hull, and is connected to the wing tanks 11a and 11b charged with the vibration reducing liquid (tank water) W and the connecting water channel 12 for communicating the lower portions of the wing tanks 11a and 11b. And an anti-vibration water tank 11 having an air duct 15 for allowing air to flow through the upper portions of the wing tanks 11a and 11b, and the air duct 15 to restrict the air flow by opening and closing the water tank. An air valve 16 for switching between operation and stop of the air valve 16 and an air valve driving device 17 for opening and closing the air valve 16 are provided.

  On the other hand, the agitated water tank control device 20 includes a central control device 21, a shake detection device 22 comprising a roll detection device 22a and a vertical shake detection device 22b, a storage device 23 for storing measurement values, analysis data, etc. A display device 24 for displaying a screen and analysis data, and an opening / closing control device 25 for sending a control signal to the air valve driving device 17 are provided.

  Then, the central control unit 21 calculates statistics of natural rolling and pitching cycles from the time-series roll angle data and pitch angle data output from the roll detection device 22a and the pitch detection device 22b. It has processing means 21a.

  Next, the control method of the anti-vibration water tank apparatus in this embodiment performed using the anti-vibration water tank apparatus comprised as mentioned above is demonstrated.

  First, the roll angle data from the roll detection device 22a and the pitch angle data from the pitch detection device 22b are input to the central controller 21. The central control device 21 calculates the rolling natural period and pitch period of the hull based on the rolling angle data and the pitch angle data, respectively.

  When the ratio between the calculated roll natural period and pitch period is approximately 1: 2, it is determined that the condition for causing parametric roll is satisfied.

  Therefore, at that time, as shown in FIG. 2, when the pitch angle is a substantially positive peak, when the roll angle alternately takes a positive and negative peak, the pitch angle shifts from positive to negative. The air valve 16 is closed near the moment, and the air valve 16 is opened near the moment when the pitch angle changes from negative to positive. As a result, the movement angle of the tank water W is delayed by 90 degrees with respect to the roll angle of the hull, the parametric roll is suppressed, and an appropriate reduction effect is exhibited.

  Similarly, as shown in FIG. 3, when the pitch angle is a substantially negative peak, when the roll angle is alternately taken as a positive peak and a negative peak, the pitch angle is around the moment when the pitch angle shifts from negative to positive. The air valve 16 is closed, and the air valve 16 is opened near the moment when the pitch angle changes from positive to negative. As a result, the movement angle of the tank water W is delayed by 90 degrees with respect to the roll angle of the hull, the parametric roll is suppressed, and an appropriate reduction effect is exhibited.

  Thus, in this embodiment, when the ratio between the pitching period of the hull and the natural period of rolling, which is a condition for generating parametric rolls, is approximately 1: 2, it is reduced by the pitch angle. By controlling the operation / stop of the shaking tank and controlling the movement of the liquid, the liquid in the shaking tank produces a 90 degree phase lag with respect to the rolling of the hull, so parametric rolling is suppressed and appropriate. Can be effective in reducing vibrations.

It is a figure which shows the rocking water tank apparatus used in one Embodiment of this invention. It is a figure which shows the relationship of the roll angle, the pitch angle, and the tank water movement angle in one Embodiment of this invention. It is a figure which shows the relationship of the roll angle, the pitch angle, and the tank water movement angle in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Shaking water tank apparatus main body 11 Shaking water tank 11a, 11b Wing tank 12 Connection channel 15 Air duct 16 Air valve 17 Air valve drive device 20 Shaking water tank control apparatus 21 Central control apparatus 21a Statistical processing means 22 Shaking detection apparatus 22a Rolling Detection device 22b Pitch detection device 23 Storage device 24 Display device 25 Opening / closing control device

Claims (1)

A water reducing tank provided with a pair of wing tanks installed on the port and starboard of a ship, a connecting water channel that communicates the lower part of the pair of wing tanks, and an air duct that communicates the upper part of the pair of wing tanks, and the air duct Based on the roll angle data and pitch angle data output from the shake detection means, and the body of the shake tank device provided with a valve for switching the operation and stop of the shake tank by opening and closing thereof In a reduced water tank device comprising a reduced water tank control device that determines the rolling natural pitch and pitch cycle of the hull and controls the opening and closing of the valve in accordance with the pitch angle,
When the ratio of pitch period to roll natural period is about 1: 2, and the pitch angle is a nearly positive peak, if the roll angle takes alternating positive and negative peaks, the pitch angle is Close the valve near the moment when it changes from positive to negative, and open the valve near the moment when the pitch angle changes from negative to positive,
When the ratio of pitch period and roll natural period is approximately 1: 2, and the pitch angle is a nearly negative peak, if the roll angle is alternating between positive and negative peaks, the pitch angle is A control method for a rocking water tank apparatus, wherein the valve is closed in the vicinity of the moment when it shifts from negative to positive, and the valve is opened near the moment when the pitch angle changes from positive to negative.

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