CN111898198B - Iterative calculation method for ship draught difference - Google Patents

Iterative calculation method for ship draught difference Download PDF

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CN111898198B
CN111898198B CN202010575921.6A CN202010575921A CN111898198B CN 111898198 B CN111898198 B CN 111898198B CN 202010575921 A CN202010575921 A CN 202010575921A CN 111898198 B CN111898198 B CN 111898198B
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丁健
张小锐
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Tangshan Port Group Co Ltd
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    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
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    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
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Abstract

The invention relates to an iterative calculation method for ship draught difference, and belongs to the technical field of calculation methods for ship operation processes. The technical scheme of the invention is as follows: (1) before the ship works, the ship parameters are input into the system; (2) in the operation process, the shore machine loads and unloads goods at different positions of each cabin, the PLC reads the real-time position of the cart mechanism to obtain x _ n, reads the flow data of the belt weigher to obtain P _ n, automatically calculates the drainage time t _ B, and calculates the draught difference t in real time through sequential iteration. The invention has the beneficial effects that: the working relation between the ship and the shore machine is established through ship data input before operation, belt weigher and cart encoder data acquisition in the operation process, so that the shore machine can master the ship trim condition in real time.

Description

Iterative calculation method for ship draught difference
Technical Field
The invention relates to an iterative calculation method for ship draught difference, and belongs to the technical field of calculation methods for ship operation processes.
Background
In recent years, the intelligent port application technology is rapidly developed. The intelligent port research content is wide, and the calculation and control of the ship draught difference in the working relation between the shore machine and the ship are important subjects. The development of intelligent ship loading and unloading is restricted by the problems that the ship state changes in real time in the loading and unloading operation process, the hardware detection technology is not mature and the like. For intelligent ship loading, ship draft difference calculation in a cabin moving stage and ship draft difference real-time control in a ship loading process are involved; for intelligent ship unloading, ship draft difference calculation in a cabin adjusting process and ship draft difference real-time control in a ship unloading process are involved.
Disclosure of Invention
The invention aims to provide an iterative calculation method for ship draught difference, which establishes a working relation between a ship and a shore machine through ship data entry before operation, belt weigher and cart encoder data acquisition in the operation process, so that the shore machine can master the ship pitching condition in real time.
The technical scheme of the invention is as follows: an iterative computation method of ship draught difference comprises the following steps:
(1) before the operation of the ship, inputting the length L of the ship, berthing bow draft d _ F, berthing stern draft d _ A, empty ship displacement delta _ L, ballast water displacement delta _ B and ballast water rated flow q _ B into a system;
(2) in the operation process, the shore machine loads and unloads goods at different positions of each cabin, the PLC reads the real-time position of the cart mechanism to obtain x _ n, reads the flow data of the belt weigher to obtain P _ n, automatically calculates the drainage time t _ B, and can calculate the draught difference t in real time through sequential iteration;
the specific formula is as follows:
Figure BDA0002550989830000021
Figure BDA0002550989830000022
Δ0＝ΔL+△B
Figure BDA0002550989830000023
Figure BDA0002550989830000024
Figure BDA0002550989830000025
the invention has the beneficial effects that: the working relation between the ship and the shore machine is established through ship data input before operation, belt weigher and cart encoder data acquisition in the operation process, so that the shore machine can master the ship trim condition in real time.
Drawings
FIG. 1 is a schematic diagram of a process for discharging ballast water from a ship;
FIG. 2 is a schematic diagram of coordinate variables of a vessel and a bank organ key point;
FIG. 3 is a schematic diagram of the relationship of the calculated variables of the draft difference of the ship.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present invention with reference to the drawings of the embodiments, and it is obvious that the described embodiments are a small part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative work based on the embodiments of the present invention belong to the protection scope of the present invention.
An iterative computation method of ship draught difference comprises the following steps:
(1) before the operation of the ship, inputting the length L of the ship, berthing bow draft d _ F, berthing stern draft d _ A, empty ship displacement delta _ L, ballast water displacement delta _ B and ballast water rated flow q _ B into a system;
(2) in the operation process, the shore machine loads and unloads goods at different positions of each cabin, the PLC reads the real-time position of the cart mechanism to obtain x _ n, reads the flow data of the belt weigher to obtain P _ n, automatically calculates the drainage time t _ B, and can calculate the draught difference t in real time through sequential iteration;
the specific formula is as follows:
Figure BDA0002550989830000031
Figure BDA0002550989830000032
Δ0＝ΔL+△B
Figure BDA0002550989830000033
Figure BDA0002550989830000034
Figure BDA0002550989830000035
when the ship is loaded and unloaded, the vertical coordinate of the gravity center of the ship and the vertical coordinate of the floating center of the ship are not in the same vertical line, and a trim moment and a ship trim are generated. The known draft difference calculation formula:
t＝dF-dA+Ltanθ
in the formula (d)FDraft the first ship; dADraft for the ship tail; l is the length of the ship;
in addition, in ship statics, the influence of loading and unloading small loads on the floating state and the initial stability of a ship has two important formulas as follows:
the longitudinal stability is high and the calculation formula is as follows:
Figure BDA0002550989830000041
pitch angle tangent calculation formula:
Figure BDA0002550989830000042
in the formula (I), the compound is shown in the specification,
Figure BDA0002550989830000043
the longitudinal stability before loading is high;
Figure BDA0002550989830000044
the longitudinal stability after loading is high; delta is the displacement; p is the load, load + and unload-; x is a loading and unloading coordinate; x is the number ofFIs the floating center coordinate; theta is a pitch angle;
substituting, we can get:
the following can be obtained:
Figure BDA0002550989830000045
Figure BDA0002550989830000046
for the shipment, P is the load weight, x is the load coordinate, Q is the drain weight, u is the drain coordinate. Draft difference of shipping operation is determined by mooring draft difference dF-dAInfluence of shipment on draft difference
Figure BDA0002550989830000047
Effect of drainage on draft differential
Figure BDA0002550989830000048
The three parts are as follows.
Figure BDA0002550989830000049
For the ship unloading operation, P is the unloading weight, x is the unloading coordinate, Q is the water injection weight, and u is the water injection coordinate. Draft difference of ship unloading operation is determined by berthing draft difference dF-dAInfluence of ship unloading on draft difference
Figure BDA00025509898300000410
Influence of pressurized water on draft differential
Figure BDA00025509898300000411
The three parts are as follows.
Figure BDA0002550989830000051
The effect of discharging ballast water on draft difference was analyzed as follows, fig. 1:
the x-z centerline plane of the ship is idealized into a rectangle, the length of the ship is shortened to a certain proportion, and the pitch angle is increased to facilitate explanation. At the initial stage of berthing, the ballast water in the tank is more, and the shadow represents the projection of the ballast water on the side surface of the ship body.
The diagonal line shading represents a sector with a radius L and a central angle θ (corresponding to an arc value α), and this area is defined as the maximum sector area:
Figure BDA0002550989830000052
the grid hatching represents another portion of the ballast water above the maximum sector, with a height h, the rectangular area:
SJ＝Lh
total ballast water area:
Figure BDA0002550989830000053
in the formula, deltaBIs the total weight of ballast water; b is the width of the ship;
for the initial stage of berthing, there are
S＝SS+SJ
Drainage area:
Figure BDA0002550989830000054
initial stage of drainage, SQAt SJWithin the range.
u＝0
The drainage coordinate is constantly 0 as shown by a series of black dots in midship.
Late stage of drainage, SQAt SSWithin the range.
u＝0.5(l-L)
Wherein l is the length of the ballast water surface;
the drainage coordinate gradually moves towards the stern direction, and along with the change of the draught difference, the drainage coordinate at different moments is greatly changed.
When residual ballast water is less than the maximum sector area
Figure BDA0002550989830000061
In the formula, alpha is an arc value corresponding to a pitch angle;
for small angles, there are
Figure BDA0002550989830000062
Thus, it is possible to provide
Figure BDA0002550989830000063
Figure BDA0002550989830000064
Figure BDA0002550989830000065
The ballast water filling during the unloading process can be regarded as the reverse process of the above process. It is noted that the influence of filling on the ship draught difference is not required to be considered in the later filling stage.
In summary, when the first operation is performed for draining, the influence of drainage on draught difference does not need to be considered. So the formula is simplified to
Figure BDA0002550989830000066
Regarding the loading and unloading of a large amount of loads as a continuous process of loading and unloading a small amount of loads, the pair
Figure 1
The terms are iteratively analyzed:
at T0Time of day, load coordinate x0Drift center coordinate xF0Load P00, displacement Δ0＝ΔL+△W+P0Then there is
Figure BDA0002550989830000071
At T1Time of day, load coordinate x1Drift center coordinate xF1Load P1Water discharge amount delta1＝Δ0+P1Then there is
Figure BDA0002550989830000072
At T2Time of day, load coordinate x2Drift center coordinate xF2Load P2Water discharge amount delta2＝Δ1+P2Then there is
Figure BDA0002550989830000073
At T3Time of day, load coordinate x3Drift center coordinate xF3Load P3Water discharge amount delta3＝Δ2+P3Then there is
Figure BDA0002550989830000074
At TnTime of day, load coordinate xnDrift center coordinate xFnLoad PnWater discharge amount deltan＝Δn-1+PnThen there is
Figure BDA0002550989830000075
Can deduce
Figure BDA0002550989830000076
And (4) loading for multiple times until the operation is finished:
Figure BDA0002550989830000077
Figure BDA0002550989830000078
1. square coefficient of
Designing a draft formula:
T＝0.0441·L1.051
hydrostatic property estimation formula other than design draft (subscript "T" represents the value under design draft)
Figure BDA0002550989830000081
Ship type coefficient formula:
Figure BDA0002550989830000082
draft formula:
Figure BDA0002550989830000083
Figure BDA0002550989830000084
Figure BDA0002550989830000085
under the condition of design draught, the square coefficient of the bulk carrier is usually 0.815-0.84, and the average value is 0.83
Figure BDA0002550989830000086
Figure BDA0002550989830000087
2. High longitudinal stability known longitudinal stability center radius formula
Figure BDA0002550989830000088
In the formula, CWIs the water plane coefficient; cBIs a square coefficient;
to obtain
Figure BDA0002550989830000091
The ship longitudinal stability is high and has the following relation with the longitudinal stability center radius:
Figure BDA0002550989830000092
in the formula (I), the compound is shown in the specification,
Figure BDA0002550989830000093
is the height of the floating core;
Figure BDA0002550989830000094
is the longitudinal stable center radius;
Figure BDA0002550989830000095
the height of the center of gravity;
Figure BDA0002550989830000096
the distance between the floating center and the center of gravity;
Figure BDA0002550989830000097
3. displacement of water during berthing
By
Δ0＝ΔL+△B
In the formula,. DELTA.LThe weight of the empty ship; deltaBIs the weight of ballast water;
4. the center of drift can be known by the Euler's law, and when the displacement keeps unchangeable condition, the same center of drift is crossed with positive waterline face to boats and ships trim waterline face, and the boats and ships trim can not change the center of drift longitudinal coordinate promptly.
Length L of prow protruding outside the stem vertical lineB
LB＝0.2B
B＝0.0734L1.1371
Wherein B is the width of the ship;
thus, it is possible to provide
LB＝0.0147L1.1371
Relative depth of immersion
hb＝0.65T
In the formula, hbThe distance from the center of the bulb nose or the forefront point or the maximum width of the bulb nose to the hydrostatic surface; establishing a coordinate system
Figure BDA0002550989830000101
Figure BDA0002550989830000102
Simulating a floating center curve by using a 3-time curve
Figure BDA0002550989830000103
Substitution into
Figure BDA0002550989830000104
Figure BDA0002550989830000105
Is finished to obtain
Figure BDA0002550989830000106
Figure BDA0002550989830000107
k＝-36096L-2.3603
Figure BDA0002550989830000108
The formula of the water discharge:
△＝ωkLBTCB
wherein omega is the weight density of water, the seawater is 1.025, and the fresh water is 1.0; k is an appendage volume coefficient which is usually 1.004-1.01, a small ship takes a large value, and a large ship takes a small value;
for any draught d, there are
Figure BDA0002550989830000109
In the formula, qBRated flow for ballast water; t is tBIn order to prolong the time of the water drainage,
Figure BDA00025509898300001010
thus, it is possible to provide
Figure BDA00025509898300001011
Figure BDA00025509898300001012
Figure BDA00025509898300001013
Figure BDA0002550989830000111
5. Loading coordinate
Referring to fig. 2, let the current position of the shore machine be xGantryAnd the ship bow position x is calibrated by utilizing the cart travelling mechanism of the shore machineForePoint, stern position xAftPoint, then there is a mid-ship position xMidDot
Figure BDA0002550989830000112
When x is equal to [ x ]Fore,xMid]Or x ∈ [ x ]Mid,xFore]Time of flight
x＝|xGantry-xMid|
Figure BDA0002550989830000113
When x is equal to [ x ]Aft,xMid]Or x ∈ [ x ]Mid,xAft]Time of flight
x＝-|xGantry-xMid|
Figure BDA0002550989830000114
In practical application, before the ship works, the length L and the berth bow draught d of the ship are measuredFBerthing stern draft dADisplacement delta of empty shipLBallast water discharge amount deltaBRated ballast water flow rate qBAnd (5) recording the system. In the operation process, the bank machine loads and unloads goods at different positions of each cabin, and the PLC reads the real-time position of the cart mechanism to obtain xnReading the flow data of the belt scale to obtain PnAnd automatically calculating the drainage time tBThrough successive iterations, the draft difference t can be calculated in real time. Of variables in and out relationship with intermediate variablesThe calculated relationship is shown in fig. 3.
The formula is as follows:
Figure BDA0002550989830000115
Figure BDA0002550989830000116
Δ0＝ΔL+△B
Figure BDA0002550989830000117
Figure BDA0002550989830000121
Figure BDA0002550989830000122

Claims (1)

1. an iterative computation method of ship draught difference is characterized by comprising the following steps:
(1) before the operation of the ship, inputting the length L of the ship, berthing bow draft d _ F, berthing stern draft d _ A, empty ship displacement delta _ L, ballast water displacement delta _ B and ballast water rated flow q _ B into a system;
(2) in the operation process, the shore machine loads and unloads goods at different positions of each cabin, the PLC reads the real-time position of the cart mechanism to obtain x _ n, reads the flow data of the belt weigher to obtain P _ n, automatically calculates the drainage time t _ B, and can calculate the draught difference t in real time through sequential iteration;
the specific formula is as follows:
Figure FDA0003660035550000011
Figure FDA0003660035550000012
Δ0＝ΔL+ΔB
Figure FDA0003660035550000013
Figure FDA0003660035550000014
Figure FDA0003660035550000015
in the formula, CBIs a square coefficient;
Figure FDA0003660035550000016
high longitudinal stability before loading, Delta0Is the initial displacement, xFAs floating center coordinate, xFnIs the floating center coordinate after iteration, x is the loading coordinate, xGantryIs the current position of the shore machine, xForeIs the bow position, xAftThe stern position.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201028969Y (en) * 2007-02-16 2008-02-27 戴水龙 Watercraft water gauge
CN105314078A (en) * 2015-09-24 2016-02-10 哈尔滨工程大学 A rapid calculation method of the draughts in hoisting work of a crane ship
CN105825061A (en) * 2016-03-17 2016-08-03 大连海事大学 Method for calculating random floating state of ship on basis of STL model

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201028969Y (en) * 2007-02-16 2008-02-27 戴水龙 Watercraft water gauge
CN105314078A (en) * 2015-09-24 2016-02-10 哈尔滨工程大学 A rapid calculation method of the draughts in hoisting work of a crane ship
CN105825061A (en) * 2016-03-17 2016-08-03 大连海事大学 Method for calculating random floating state of ship on basis of STL model

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
一种船舶吃水差的精确计算方法;邱文昌 邱强;《航海技术》;20060721;全文 *

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