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CN119166955B - A method for calculating the emergency anchor-dragging braking distance of a ship - Google Patents

A method for calculating the emergency anchor-dragging braking distance of a ship Download PDF

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CN119166955B
CN119166955B CN202411658889.2A CN202411658889A CN119166955B CN 119166955 B CN119166955 B CN 119166955B CN 202411658889 A CN202411658889 A CN 202411658889A CN 119166955 B CN119166955 B CN 119166955B
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anchor
ship
braking distance
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water
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CN119166955A (en
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张东
石利勇
娄友明
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Tianjin Port Pilot Center
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Tianjin Port Pilot Center
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Abstract

The application discloses a method for measuring and calculating the braking distance of an emergency drag anchor of a ship, which comprises the steps of establishing a ship deceleration motion equation according to water resistance acting on a ship body, dynamic holding power of the anchor during braking and Newton's second law, obtaining a longitudinal additional mass experience value of a moving ship, accordingly obtaining a water resistance coefficient relation, fitting out corresponding anchor dynamic holding power coefficients of the anchor under different ratios of chain length and anchoring depth to obtain dynamic holding power functions of a common rodless anchor and a large holding power anchor, substituting the obtained water resistance coefficient relation and the dynamic holding power function of the anchor into the ship deceleration motion equation to obtain an estimated formula of the braking distance of the drag single anchor of the common rodless anchor ship and an estimated formula of the braking distance of the drag single anchor of the large holding power anchor ship. The measuring and calculating method considers the influence of physical parameters such as the additional mass of the ship, the water resistance and the like on the drag anchor braking distance, and is more scientific and reasonable compared with the existing drag anchor braking distance estimation formula, larger in applicable ship speed range and more reliable in calculation result.

Description

Ship emergency drag anchor braking distance measuring and calculating method
Technical Field
The invention relates to the technical field of braking distance calculation, in particular to a method for measuring and calculating the braking distance of an emergency drag anchor of a ship.
Background
When the ship sails and needs emergency braking, the conventional ship braking can be divided into the following main forms according to different working principles and technical means:
And the reversing braking is realized by switching the host machine to a reversing mode and utilizing reverse thrust when the rapid deceleration or the ship stopping is required. This approach is particularly effective in emergency situations.
And after the ship is fully steered leftwards or rightwards, the ship is braked in a rotating way, the ship sailing resistance and rudder resistance are increased, and the ship speed is obviously reduced. This approach is applicable to open waters.
And Z-shaped braking, namely, in order to protect the host, firstly, the left rudder and the right rudder are repeatedly operated to reduce the ship speed, and when the ship speed is reduced to be lower, the ship is backed up, and the ship is stopped as soon as possible. This approach is particularly effective at higher initial speeds.
And the drag anchor brakes, namely, the anchor can be thrown down to generate resistance under emergency conditions, so that the ship is helped to be decelerated more quickly or stopped in time. Thus, the anchor is the "second life" of the captain and pilot, and when in confined waters, the ship is out of control due to sudden machine failure, encounters extreme weather, and is unable to navigate safely, and is in urgent danger with other ships or facilities, the pilot typically throws the anchor further to control the state of motion of the ship in order to avoid marine traffic accidents or reduce accident losses. In anchor practice, whether emergency risk avoidance or safe operation is performed, the most attention of the driver is on the braking distance of the ship anchor. However, in the prior art, for calculating the braking distance of the drag anchor, most of the calculation depends on the experience value of the driver, and no clear calculation standard is standardized. Therefore, the application provides a method for measuring and calculating the braking distance of the emergency drag anchor of the ship, which solves the problems.
Disclosure of Invention
Therefore, the invention aims to provide a method for measuring and calculating the braking distance of the emergency towline of the ship, which provides theoretical basis and data support for the operation of the emergency towline.
In order to achieve the above purpose, the method for measuring and calculating the braking distance of the emergency drag anchor of the ship comprises the following steps:
S1, establishing a ship deceleration motion equation according to water resistance acting on a ship body when the ship moves to water, dynamic holding power of an anchor during drag anchor braking and Newton' S second law
Wherein: Braking distance for the towing anchor; known as the inertia coefficient; is the water resistance coefficient; at the initial speed of the vehicle, the vehicle is at a speed, Is the dynamic holding power of the anchor; adding mass to the longitudinal direction of the moving vessel;
S2, acquiring a longitudinal additional mass empirical value of the moving ship, and obtaining a water resistance coefficient relation according to the longitudinal additional mass empirical value of the moving ship;
S3, fitting the corresponding anchor dynamic holding power coefficients of the anchors under the different ratios of the chain length and the anchoring depth to obtain a dynamic holding power function of a common rodless anchor and a dynamic holding power function of a large-holding-power anchor;
s4, bringing the water resistance coefficient relation obtained in the steps S2 and S3 and the dynamic grabbing function of the anchor into a ship deceleration motion equation of the step S1 to obtain
Formula for estimating brake distance of single anchor of common rodless anchor ship
Estimation formula of single-anchor braking distance of large-grab-force anchor ship
Further preferably, the water resistance comprises wave making resistance, friction resistance and vortex resistance, wherein the friction resistance is in direct proportion to 1.852 times of the water speed of the ship, the wave making resistance is in direct proportion to 4 times of the water speed of the ship, and the vortex resistance is in direct proportion to the square of the water speed of the ship;
according to the ship entering and exiting ports, the ship has small water movement speed and is simplified into water resistance ;Is the water resistance coefficient; Is the movement speed of the ship to the water.
Further preferably, the range of the empirical value of the longitudinal additional mass of the moving ship is 0.07 m-0.1 m, and the longitudinal additional mass of the moving ship is selected in shallow water,Is the mass of the ship.
Further preferably, in S3, obtaining the corresponding anchor dynamic holding power of the anchor under the different ratios of the chain length and the anchoring depth, and fitting the anchor dynamic holding power comprises the following steps:
s301, according to a general formula of the dynamic gripping force of the anchor:
s302, fitting the dynamic holding power of the anchor under the different ratios of the chain length and the anchoring depth to obtain a dynamic holding power coefficient fitting formula of the anchor
N is a multiple of the outgoing chain, and the ratio of the outgoing chain length to the anchoring depth is different;
s303, fitting formula of dynamic holding power coefficient of anchor Substituting the general formula of the dynamic holding power of the anchor to obtain the dynamic holding power function of the common rodless anchor
;
According to the grasping power of the large grasping power anchor which is 2 times of the grasping power of the common rodless anchor, the dynamic grasping power function of the large grasping power anchor。
Further, the method preferably further comprises the steps of S5, using an oil tanker S wheel, a C wheel, a K wheel and a container ship W wheel as sample ships, estimating the drag anchor braking distances of all the sample ships under the conditions of different initial speeds and different chain lengths, judging actual influence factors of the drag anchor braking distances according to drag anchor braking distance estimation results, and drawing a change chart of water outlet resistance and single-anchor grasping power under the conditions of different chain lengths and different anchor anchoring depths to verify estimation accuracy.
Compared with the prior art, the method for measuring and calculating the braking distance of the ship emergency drag anchor has at least the following advantages:
1. the method for measuring and calculating the braking distance of the emergency drag anchor of the ship disclosed by the application considers the influence of physical parameters such as the additional mass, the water resistance and the like of the ship on the braking distance of the drag anchor, and compared with the existing estimation method for the braking distance of the low-speed drag anchor of the ship, the method is more scientific and reasonable, and the calculation result is more reliable.
2. The method for measuring and calculating the braking distance of the ship emergency drag anchor is simple and practical, and the driver can obtain the braking distance of the ship drag anchor by means of a stopwatch, a calculator and other tools built in a mobile phone.
3. According to the method for measuring and calculating the braking distance of the emergency towrope of the ship, disclosed by the application, a driver can estimate the braking distance of the towrope of the ship in a typical loading state in advance, and can determine the maximum field of the braking motion of the towrope of the ship by taking the ship position when the chain is loosened to the planned chain length as the circle center and taking the braking distance of the towrope as the radius, so that a correct decision can be timely and effectively made when the ship encounters an abnormal situation.
Drawings
Fig. 1 is a schematic flow chart of a method for measuring and calculating the braking distance of an emergency drag anchor of a ship.
Figure 2 shows that the method for measuring and calculating the braking distance of the emergency drag anchor of the ship is used for the S wheel,And respectively taking change graphs of water resistance and single-anchor holding power when 2,3, 4 and 5 are taken.
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description.
The braking motion of the ship drag anchor is a non-uniform deceleration motion. In order to estimate the braking distance of a ship towing anchor, the following conditions are generally assumed that in a flat still water area on the sea bottom, after the anchor falls to the bottom, the fluke can be meshed into the bottom soil and does not turn over, namely the dynamic gripping power of the anchor is constant, the anchor always keeps linear motion, and the anchor is only acted by water resistance and anchor chain pulling force in the horizontal direction, wherein the anchor chain pulling force depends on the dynamic gripping power of the anchor.
As shown in fig. 1, the method for measuring and calculating the braking distance of the emergency drag anchor of the ship according to the embodiment of the invention comprises the following steps:
s1, establishing a ship deceleration motion equation according to water resistance acting on a ship body when the ship moves to water, dynamic holding power of an anchor when a drag anchor brakes and Newton' S second law;
(equation 7)
Wherein: the braking distance of the drag anchor is m; referred to as the inertia coefficient, m; the unit of (3) is N.s 2/m2; In m/s.
To determine the braking movement distance of the ship drag anchor, the longitudinal additional mass of the moving ship is neededCoefficient of water resistanceAnd the dynamic holding power of the anchorAnd assigning or determining a calculation method for the motion parameters.
S2, acquiring a longitudinal additional mass empirical value of the moving ship, and obtaining a water resistance coefficient relation according to the longitudinal additional mass empirical value of the moving ship;
when the ship moves to water, the water resistance acting on the ship body Mainly comprises friction resistance, wave making resistance and vortex resistance. Wherein, the friction resistance is in direct proportion to 1.852 times of the speed of the ship to water, the wave making resistance is in direct proportion to 4 times of the speed of the ship to water, and the vortex resistance is in direct proportion to the square of the speed of the ship to water. Since the ship has a low water movement speed, a small Froude number and a small wave-making resistance during the departure and departure, it is considered that the water resistance acting on the hull is proportional to the square of the water movement speed of the ship, i.e
(Equation 1)
Wherein: is water resistance, N; is the water resistance coefficient; for the movement speed of the ship to the water, m/s
When the ship drag anchor brakes, the horizontal component force of the anchor chain tension acts on the ship bodyMainly from the dynamic grip of the anchorIt can therefore be considered that the chain tension acting on the hull is equal to the dynamic grip of the anchor, i.e
(Equation 2)
Wherein: the unit N is the dynamic holding power of the anchor; Is the dynamic gripping force coefficient of the anchor; Is the anchoring weight in the air, unit N; the mass of the single anchor is kg; Gravitational acceleration of 9.8m/s 2
When the ship drag anchor brakes, the ship drag anchor is acted by water resistance and anchor chain tension, and the two forces are opposite to the ship motion direction, so the ship drag anchor is obtained according to Newton's second law:
(equation 3)
Wherein: The weight of the ship is kg; for the longitudinal addition of mass to the vessel, unit kg; The speed reducing time of the ship drag anchor is given by the unit s; Is the instantaneous acceleration of the ship, unit . The differentiation principle is as follows:
(equation 4)
Substituting the formulas (1), (2) and (4) into the formula (3), and finishing to obtain the following formula:
(equation 5)
For equation (5) in intervalThe default integral processing includes:
(equation 6)
Wherein: For the ship speed To fall toThe braking distance of the drag anchor; Is the initial speed; is the final speed. Order the At 0, can be obtained:
(equation 7)
Wherein: the braking distance of the drag anchor is m; referred to as the inertia coefficient, m; the unit of (3) is N.s 2/m2; In m/s.
To determine the braking movement distance of the ship drag anchor, the longitudinal additional mass of the moving ship is neededCoefficient of water resistanceAnd the dynamic holding power of the anchorAnd assigning or determining a calculation method for the motion parameters.
For the longitudinal additional mass of a moving vesselWhen the ship sails, the surrounding water body is driven to move together, and the mass of the water body is the additional mass, and the size of the additional mass is related to the shape of the underwater hull, the roughness of the hull, the ratio of the draft to the depth of the ship, the vibration of the ship and the like. Ship model experiments show that the longitudinal additional mass of the ship is (0.07-0.1)For most large and medium-sized inbound and outbound ships, the navigable water area in the harbor is shallow water, so 0.1 is taken outAs an additional mass for the drag anchor to brake the vessel.
1. For water resistance coefficientIn order to obtain the water resistance coefficient, the ship inertia coefficient needs to be obtained first.
1) The expression of the inertia coefficient of the ship during parking braking is
(8)
In the formula,Is self-containedDown toTime required.
When the ship is braked at low speed and is in a linear motion state, a driver can read from the GPS positioning terminal、Is measured simultaneously with a stopwatchIs a value of (2). Substituting the measured value into equation (8) to calculate the value of the inertia coefficient.
Practice proves that the more reasonable the selected speed interval is, the longer the observation time is, and the higher the reliability of the inertia coefficient calculated according to the formula (8) is.
2) Adding the longitudinal additional mass of the ship to 0.1Substituting into (8), and finishing to obtain
(9)
Substituting the values of the ship mass and the ship inertia coefficient into the formula (9) to obtain the value of the water resistance coefficient.
2. Dynamic grip on anchor
S3, fitting the corresponding anchor dynamic holding power coefficients of the anchors under the different ratios of the chain length and the anchoring depth to obtain a dynamic holding power function of a common rodless anchor and a dynamic holding power function of a large-holding-power anchor;
To obtain dynamic holding power formulas of anchors under different ratios of chain length to water depth, sediment substrate is selected, and dynamic holding power coefficients of anchors are fitted, so that the dynamic holding power coefficient expression of the common rodless anchor is obtained
(10)
Wherein: the ratio of the chain length to the water depth is the chain output multiple.
The fitting value and the fitting error value are shown in table 1, and it is understood that the calculation accuracy of the fitting equation (10) is very high and can be directly referred to.
TABLE 1 dynamic grip coefficient [4] and fitting error value for common rodless anchors at different ratios of chain length to water depth
According to the reference, the holding power of the large-holding-power anchor is at least 2 times of that of a common rodless anchor with the same mass, so that the dynamic holding power coefficient expression of the large-holding-power anchor can be determined as
(11)
Substituting the formula (10) into the formula (2) to obtain the dynamic holding power expression of the common rodless anchor
(12)
Substituting the formula (11) into the formula (2) to obtain the dynamic gripping force expression of the high-gripping-force anchor
(13)
The vessels are classified into vessels equipped with a general rodless anchor and vessels equipped with a large-grip anchor in order to obtain an expression of a braking distance of a vessel drag anchor.
1) Drag anchor braking distance of ship equipped with ordinary rodless anchor
Will beSubstituting (12) into (7), and sorting to obtain an estimated formula of the brake distance of the trawling unit of the ship with the ordinary rodless anchor
(14)
2) Drag anchor braking distance of ship equipped with large-grab anchor
Will beSubstituting (13) into (7), and finishing to obtain an estimated formula of the brake distance of the trawling anchor of the anchor ship with large holding power
(15)
The method comprises the steps of S4, estimating the drag brake distance of all sample ships under the conditions of different initial speeds and different chain lengths by using an oil tanker S wheel, an oil tanker C wheel, an oil tanker K wheel and a container ship W wheel as sample ships, judging actual influence factors of the drag brake distance according to the drag brake distance estimation result, and drawing a change chart of water outlet resistance and single-anchor holding power under the conditions of different chain lengths and different anchoring depths to verify estimation accuracy.
In order to facilitate the visual understanding of the algorithm of the drag brake distance of the ship by the person skilled in the art and to explore the change rule of the drag brake distance of the ship, the S wheel of the oil tanker, the C wheel, the K wheel and the W wheel of the container ship are selected as sample ships (main data are listed in the table 2), and the drag brake distances of the commercial ships under the conditions of different initial speeds and different chain lengths are estimated.
Table 2 main data of sample vessels
The initial speed of the ship during low-speed parking braking is measuredFinal speedAnd a deceleration timeSubstituting the formula (8), calculating the inertia coefficient of the shipAnd (3) substituting the values of the ship mass and the inertia coefficient into the formula (9) to calculate the water resistance coefficient of the shipThe values of (2) are shown in Table 3
TABLE 3 measurement of sample vessel speed, parking time and calculated values of coefficient of inertia and coefficient of water resistance
According to the anchor formula (14) or (15) provided by the ship, parameter values such as the ship mass, the water resistance coefficient, the anchor mass and the like are substituted into the corresponding expression, and an estimated formula of the braking distance of the ship drag anchor can be obtained.
The practical estimation of the braking distance of the S wheel single anchor is
(16)
According to the method, for a specific ship, the drag anchor braking distance is only related to the initial speed and the out-chain multiple of the ship, and when the double-anchor braking is carried out, the pulling force of the anchor chain acting on the ship body is 2 times of the single-anchor gripping force. Accordingly, assume an initial velocityThe values of (1) are 8kn, 6kn, 4kn, 3kn and 2kn respectively (kn is converted into m/S in calculation), and the drag anchor braking distances of the S wheels are calculated respectively assuming that the chain multiples are 2,3, 4 and 5 respectively, and the specific values are shown in Table 4
TABLE 4S wheel drag anchor braking distance
The practical estimation of the braking distance of the C wheel single anchor is
(17)
Similarly, the drag anchor braking distance for wheel C can be calculated as set forth in Table 5.
TABLE 5C wheel drag anchor braking distance
The practical estimation of the braking distance of the K wheel single anchor is
(18)
Similarly, the drag anchor braking distance for the K wheels can be calculated as set forth in Table 6.
TABLE 6K wheel drag anchor braking distance
The practical estimation of the braking distance of the single anchor of the W wheel is
(19)
Similarly, the drag anchor braking distance for the W wheel can be calculated as set forth in table 7.
TABLE 7W wheel drag anchor braking distance
The following rules can be found by comparing and analyzing the braking distances of the ship drag anchors listed in tables 4-7:
1) For any ship, the drag anchor braking distance has the following characteristics:
① The drag anchor braking distance is obviously reduced along with the increase of the outgoing chain multiple, and the drag anchor braking distance reduction amplitude is obviously reduced along with the increase of the outgoing chain multiple.
② The drag anchor braking distance is obviously reduced along with the reduction of the initial speed of the ship, and the reduction amplitude of the drag anchor braking distance is obviously reduced along with the reduction of the initial speed.
③ The braking distance of the ship when towing the double anchor is smaller than that of the ship when towing the double anchor, and the braking distance of the ship when towing the double anchor is infinitely close to but always smaller than 2 times that of the ship when towing the double anchor along with the reduction of the initial speed and the increase of the out-chain multiple.
2) Comparing the drag anchor braking distances of the S wheel and the C wheel shows that for the ship with the square coefficient being close and the same anchor type, the larger the water displacement, the larger the corresponding drag anchor braking distance.
3) As can be seen from comparison of the drag anchor braking distances of the wheels C and K, the drag anchor braking distance of the ship provided with the large-grabbing-force anchor is smaller for the ship with the square coefficient close to that of the ship with the approximately same water displacement.
4) Comparing the braking distance of the drag anchors of the wheels K and W, the smaller square coefficient and larger water resistance of the ship body are for the ship with approximately equal displacement and the same anchor, and on the other hand, the larger the outfitting number of the ship is, the larger the mass of the anchor is, and the larger the dynamic holding power of the anchor is. Therefore, the drag anchor braking distance of the W wheel is obviously smaller than that of the K wheel.
At present, when a person skilled in the art estimates the braking distance of a drag anchor in the prior art, an estimation formula given by a rock well smart based on a kinetic energy theorem is generally adopted
(20)
Wherein: the displacement of the ship is t; is the initial ship speed, kn; Is the dynamic holding power of the anchor, t.
Selecting an S wheel as a research object, substituting a formula (12) into the formula (20), substituting parameter values such as ship drainage, anchor quality and the like, and finishing to obtain a drag anchor braking distance estimation formula when the S wheel drag single anchor is obtained as follows
(21)
Similarly, assuming that the dynamic holding power of the double anchors is 2 times of that of the single anchors when the double anchors are towed for braking, the initial speed is highThe drag anchor braking distances when the values are respectively 8kn, 6kn, 4kn, 3kn and 2kn and the chain output multiples are respectively 2, 3, 4 and 5 are selected, and the specific calculation results are shown in Table 8
TABLE 8 evaluation formula value of braking distance of S wheel drag anchor
Comparing the data in table 4 with the data in table 8, the following features can be found:
1) When the initial speed of S wheel drag anchor braking is 8kn and 6kn, the calculated value according to the formula (20) is obviously larger than the calculated value according to the formula (16), and the larger the initial speed is, the smaller the chain output multiple is, and the larger the difference value of drag anchor braking distances is.
2) When the initial speed of the S wheel drag anchor braking motion is 4kn, 3kn and 2kn, the calculated value according to the formula (20) is slightly different from the calculated value according to the formula (16) along with the difference of the output chain multiples.
3) The data in Table 8 shows that under the condition of the same initial speed, the braking distance of the S wheel single anchor is 2 times of that of the double anchor.
The estimation formula (20) given by the rock well intelligence based on the kinetic energy theorem adopted in the prior art is compared with the estimation formula (14) of the trawling anchor braking distance of the common rodless anchor ship and the estimation formula (15) of the trawling anchor braking distance of the large-grab anchor ship.
1) The prior art estimation formula (20) does not take into account the effect of the additional longitudinal mass of the vessel on the drag anchor braking distance, whereas the present estimation formulas (14), (15) relate to the additional longitudinal mass of the vessel.
2) The prior art estimation formula (20) does not relate to water resistance, whereas the present application estimation formulas (14), (15) embody the influence of water resistance on the braking distance of the ship drag anchor.
To further clarify the influence of water resistance on the braking distance of the ship drag anchor, taking an S wheel as an example, the water resistance born by the S wheel is compared with the dynamic holding power of a single anchor.
The S wheel receives water resistance as follows:
(22)
The dynamic holding power of the single anchor is as follows:
(23)
according to (22), (23), And respectively taking 2, 3,4 and 5, and drawing a change chart of water outlet resistance and single-anchor holding power by using drawing software, as shown in figure 2.
When the movement speed of the S wheel set water is 4.7kn, the water resistance of the S wheel set water is equal to the dynamic grabbing force of the anchor under the condition that the chain length is 2 times of the water depth, the water resistance is rapidly increased along with the increase of the water speed, and when the movement speed of the S wheel set water is 8.2kn, the water resistance of the S wheel set water is equal to the dynamic grabbing force of the anchor under the condition that the chain length is 5 times of the water depth. Obviously, the higher the movement speed of the S wheel to the water, the larger the influence of the water resistance to the drag anchor braking distance, and the more distorted the calculated value of the estimation formula (20).
When the water speed of the S wheel set is 3KN, the water resistance is 20.2KN, and when the water speed of the S wheel set is 2KN, the water resistance is 9.0KN. From this, it can be seen that the lower the speed of movement of the S wheel with respect to the water, the smaller the influence of the water resistance on the drag anchor braking distance, and the smaller the error of the calculated value obtained according to the formula (20).
In summary, the estimation formula (20) in the prior art is only suitable for estimating the drag anchor braking distance when the initial speed of the ship is low (less than 4 kn), while the estimation formulas (14) and (15) in the application indicate that the drag anchor braking distance is related to the water resistance, and the estimation formula is suitable for calculating the drag anchor braking distance under the condition of high ship speed, so that the application range of the formula (14) and (15) in the application is wider, and the calculation result is more accurate when the ship is rapidly anchored in the middle and low speed running process.
1) The equations (14) and (15) take the influence of physical parameters such as the additional mass of the ship, the water resistance and the like on the braking distance of the drag anchor into consideration, and compared with the traditional low-speed drag anchor braking distance estimation equation of the ship, the method is more scientific and reasonable and has more reliable calculation results.
2) The estimation method is simple and practical, and the driver can obtain the drag anchor braking distance of the ship only by using application software such as a stopwatch and a calculator built in a mobile phone.
3) According to the method provided by the application, the driving personnel can estimate the drag anchor braking distance of the ship in a typical loading state in advance, take the ship position when the chain is loosened to the planned chain length as the circle center, and take the drag anchor braking distance as the radius, so that the maximum field of the drag anchor braking motion of the ship can be determined, and the correct decision can be timely and effectively made when the ship encounters an abnormal situation.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims (4)

1.一种船舶应急拖锚制动距离测算方法，其特征在于，包括以下步骤：1. A method for calculating the emergency anchor-dragging braking distance of a ship, characterized in that it comprises the following steps: S1、根据船舶对水运动时的作用于船体的水阻力、拖锚制动时锚的动抓力和牛顿第二定律，建立船舶减速运动方程S1. According to the water resistance acting on the hull when the ship moves against the water, the dynamic grip of the anchor during anchor dragging and braking, and Newton's second law, the ship deceleration motion equation is established. 式中：为拖锚制动距离；被称为惯性系数；为水阻力系数；为初始速度，为锚的动抓力；为运动船舶的纵向附加质量；m为船舶质量；Where: is the anchor-hauling braking distance; is called the coefficient of inertia; is the water resistance coefficient; is the initial velocity, is the dynamic holding force of the anchor; is the longitudinal additional mass of the moving ship; m is the mass of the ship; S2、获取运动船舶的纵向附加质量经验值，根据运动船舶的纵向附加质量经验值，得到水阻力系数关系式；S2. Obtaining the longitudinal added mass empirical value of the moving ship, and obtaining the water resistance coefficient relationship according to the longitudinal added mass empirical value of the moving ship; S3、拟合出锚在不同出链长度与抛锚深度之比下，对应的锚动抓力系数，得到普通无杆锚的动抓力函数和大抓力锚的动抓力函数；获取锚在不同出链长度与抛锚深度之比下，对应的锚动抓力，进行拟合包括以下步骤：S3, fitting the corresponding anchor dynamic grip coefficient under different ratios of the chain length to the anchoring depth, obtaining the dynamic grip function of the common stockless anchor and the dynamic grip function of the large grip anchor; obtaining the corresponding anchor dynamic grip under different ratios of the chain length to the anchoring depth, and fitting includes the following steps: S301、根据锚的动抓力一般公式：S301. According to the general formula of the dynamic holding force of the anchor: S302、 对锚在不同出链长度与抛锚深度之比下的锚的动抓力进行拟合，得到锚的动抓力系数拟合公式S302, fitting the dynamic holding force of the anchor at different ratios of the chain length to the anchoring depth, and obtaining a fitting formula for the dynamic holding force coefficient of the anchor 为出链倍数，不同出链长度与抛锚深度之比；m a 为单锚质量； is the chain out multiple, the ratio of different chain out lengths to anchor depth; ma is the mass of a single anchor; S303、将锚的动抓力系数拟合公式代入锚的动抓力一般公式，得到普通无杆锚的动抓力函数S303, fitting formula of dynamic holding force coefficient of anchor Substituting into the general formula of the dynamic holding force of the anchor, the dynamic holding force function of the common stockless anchor is obtained: ； ; 根据大抓力锚的抓力为普通无杆锚抓力的2倍，大抓力锚的动抓力函数；According to the holding force of the large holding force anchor is twice that of the ordinary stockless anchor, the dynamic holding force function of the large holding force anchor ; S4、将S2和S3得到的水阻力系数关系式和锚的动抓力函数，代入S1的船舶减速运动方程中，得到S4, Substitute the water resistance coefficient relationship obtained in S2 and S3 and the anchor dynamic grip function into the ship deceleration motion equation in S1 to obtain 普通无杆锚船舶的拖单锚制动距离的估算公式Estimation formula for the braking distance of a common stockless anchor vessel 大抓力锚船舶的拖单锚制动距离的估算公式Estimation formula for the braking distance of a single anchor for a ship with a large holding power anchor 。 . 2.根据权利要求1所述的船舶应急拖锚制动距离测算方法，其特征在于，所述水阻力包括兴波阻力、摩擦阻力和涡流阻力；所述摩擦阻力与船舶对水速度的1.852次方成正比；兴波阻力与船舶对水速度的4次方成正比；涡流阻力与船舶对水速度的平方成正比；根据船舶进出港时，船舶对水运动速度小，简化为水阻力；为水阻力系数；为船舶对水的运动速度。2. The method for calculating the emergency anchor dragging braking distance of a ship according to claim 1 is characterized in that the water resistance includes wave-making resistance, friction resistance and eddy current resistance; the friction resistance is proportional to the 1.852 power of the ship's speed against the water; the wave-making resistance is proportional to the fourth power of the ship's speed against the water; the eddy current resistance is proportional to the square of the ship's speed against the water; when the ship enters and leaves the port, the ship's speed against the water is small, which is simplified to water resistance. ; is the water resistance coefficient; is the speed of the ship moving through the water. 3.根据权利要求1所述的船舶应急拖锚制动距离测算方法，其特征在于，所述运动船舶的纵向附加质量经验值的范围为0.07m～0.1m，为船舶质量，浅水中，运动船舶的纵向附加质量选取。3. The method for calculating the emergency anchor dragging braking distance of a ship according to claim 1, characterized in that the range of the empirical value of the longitudinal additional mass of the moving ship is 0.07m to 0.1m, is the ship mass, the longitudinal additional mass of a moving ship in shallow water is selected . 4.根据权利要求1所述的船舶应急拖锚制动距离测算方法，其特征在于，还包括S5、采用油船S轮、C轮、K轮和集装箱船W轮为样本船舶，对所有样本船舶在不同初速度、不同出链长度条件下的拖锚制动距离进行估算；根据拖锚制动距离估算结果，判断拖锚制动距离实际影响因素，绘制不同出链长度与抛锚深度之比下船舶所受水阻力和单锚动抓力的变化图。4. The method for calculating the emergency anchor dragging and braking distance of a ship according to claim 1 is characterized in that it also includes S5, taking oil tankers S, C, K and container ship W as sample ships, estimating the anchor dragging and braking distances of all sample ships under different initial velocities and different chain lengths; judging the actual influencing factors of the anchor dragging and braking distance according to the estimated results of the anchor dragging and braking distance, and drawing a change diagram of the water resistance suffered by the ship and the single anchor dynamic gripping force under different ratios of chain lengths to anchoring depths.
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