RU2509032C1 - Method for determination of crosswise hydrodynamic force and its moment in ship complex maneuvering - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to control over ship course in complex maneuvering at mooring, dynamic position or drifting. Proposed method consists in that prior to performing complex maneuvering, ship rotates under effects of active control means, for example, lateral thrusting propeller. Note here that ship angular ω and spinning moment M_pr produced by lateral thrusting propeller are calculated. Angular speed ω and spinning moment M_pr are used to define hydrodynamic factor c₂ and transverse component of hydrodynamic force Y_β, formed at ship hull in its motion with the help of log and formula: Y_β=C_yβ0,5ρυ²F_dp, here C _yβ≅c₂, ρ is water bulk density; υ is ship linear speed; F_dp is reduced area of centerline buttock.

EFFECT: higher efficiency and safety of complex maneuvering.

Description

The invention relates to controlling the trajectory of a vessel performing complex maneuvering during mooring or dynamic positioning.

The purpose of the invention is the improvement of control of a vessel performing complex maneuvering.

Improving the management of a vessel performing complex maneuvering is achieved by predicting its movement by computer simulation using a mathematical model of the vessel.

The effectiveness and safety of performing complex maneuvers depend on the availability of the necessary information to adequately assess the nature of the behavior of the vessel when it is exposed to internal or external control actions. In this case, the actions in the form of forces and moments generated as a result of the propulsion and steering complex of the vessel or propulsion and steering complexes of auxiliary (external) controls, for example tugs, are considered as control actions.

It is impossible to predict the behavior of a vessel when performing complex maneuvering as a result of control actions without determining the hydrodynamic parameters of its mathematical model, in particular, the value of the transverse hydrodynamic force generated on the ship's hull during its movement.

Due to the lack of appropriate technical means of measuring the hydrodynamic force generated on the hull of the vessel during its movement, it seems possible to determine it by calculation and experimental method.

A known method of determining the hydrodynamic parameters of the mathematical model of the vessel (Pat. No. 2442718, publ. 02.20.2012).

The method is based on the measurement using the receivers of a satellite navigation system with differential corrections in real time of the coordinates of two points spaced apart in the diametrical plane along the length of the vessel, conventionally called bow and stern, and determining, using the measurement results of the current coordinates of these points, current values, kinematic parameters of the vessel:

- linear speeds of the bow F (υ _f ) and stern A (υ _а ) points and their projections onto the longitudinal X (υ _xf , υ _ха ) and transverse Y (υ _yf , υ _ya ) coordinate axes of the ZXOY coordinate system associated with the vessel (see figure 1);

- abscissas of the center of rotation (x ₀ ) in the ZXOY coordinate system;

- projections of the linear velocity vector at the center of gravity on the transverse axis Y (υ _y );

- linear velocity of the center of gravity of the vessel (υ);

- radius of curvature of the trajectory of the center of gravity of the vessel (R);

- angular velocity of the vessel (ω);

which are used to calculate the current values of the hydrodynamic parameters of the mathematical model of the vessel, on the basis of which computer simulation is performed to predict the movement of the vessel during maneuvering.

However, there are such types of maneuvering when it is not necessary to determine all the hydrodynamic parameters of its mathematical model to predict the movement of the vessel, as indicated above (Pat. No. 2442718), it is sufficient to determine only the value of the transverse component of the hydrodynamic force generated on the ship's hull during its movement. These types of maneuvering include mooring operations, dynamic positioning, and ship drift. A distinctive feature of such maneuvers is that, drifting, performing a mooring operation, positioning, the vessel moves with a lag, while the values of the drift angles are in the range of 90 ± 20 ° [2], [3], [5]. This allows you to calculate the value of the transverse component of the hydrodynamic force generated during the movement of the vessel using the value of only one hydrodynamic parameter of the mathematical model of the vessel.

The objective of the proposed method is to significantly reduce the number of parameters of the mathematical model used to predict the movement of the vessel in the process of maneuvering, and, as a result, reduce the probability of forecast errors and increase the level of its reliability and quality.

The method is as follows. The value of the transverse component of the hydrodynamic force generated on the hull of the vessel during its movement is determined by the dependence:

$$Y_{\beta }=C_{y\beta }0.5\rho {\upsilon }^2{F}_{dp},\left(\text{one}\right)$$

where C _yβ is the coefficient of the transverse component of the hydrodynamic force;

ρ is the mass density of water;

υ is the linear speed of the vessel;

F _dp - the reduced area of the diametrical buttocks of the vessel.

The coefficient of the transverse component of the hydrodynamic force is calculated by the formula:

$$C_{y\beta }=0.5c_{\mathrm{one}}\sin 2\beta \cos \beta +c_2\sin \beta |\; |\; |\sin \beta |\; |\; |+c_3{\sin }^{\mathrm{four}}2\beta sign\beta ,\left(\text{2}\right)$$

here c ₁ , c ₂ , c ₃ are the hydrodynamic coefficients determined by the calculation method using the known calculated dependences [4], while the numerical value of the coefficient c _{2 is} an order of magnitude higher than the values of the coefficients c ₁ , c ₃ ; β is the drift angle.

It follows from expression (2) that, at drift angles close to 90 °, it can be replaced by the dependence

$$C_{y\beta }\cong c_2.\left(\text{3}\right)$$

The difference in the values of the coefficient C _yβ when calculated by formulas (3) and (2), in the range of drift angles 90 ± 20 °, is no more than 10%, which meets the requirements for the accuracy of determining the forces generated on the hull of a vessel during its movement [2 ].

To determine the value of the transverse component of the hydrodynamic force generated on the hull of the vessel during its movement, one can use dependence (3), the unknown hydrodynamic parameter in which is only the coefficient c ₂ .

To determine the value of the coefficient c _2, it is necessary to rotate the hull under the influence of active controls, such as a bow thruster.

Thus, the procedure for determining the value of the transverse component of the hydrodynamic force generated on the hull of the vessel during its movement by the lag is as follows. Before performing complex maneuvering, the vessel rotates under the influence of active controls, such as a thruster, and the angular velocity ω of the vessel is measured and the torque generated by the thruster is calculated

$$M_{pr}=T_{epr}\times x_{pr},\left(\text{four}\right)$$

where T _epr is the thrust of the thruster; x _pr is the abscissa of the thruster channel.

Using the values of the angular velocity ω and torque M _pr in accordance with the formula presented in [3], we calculate the value of the coefficient c ₂

$$c_2=\mathrm{29,645}{M}_{pr}/\left({\omega }^2{L}^{\mathrm{four}}\rho d\right),\left(\text{5}\right)$$

where L is the length of the vessel; d is the average draft of the vessel.

Based on dependencies (3), (1), we find the magnitude of the transverse component of the hydrodynamic force generated on the hull of the vessel when it moves with a lag.

Literature

1. Bassin, A.M. Speed and controllability of ships. / A.M. Basin. - M.: Transport, 1967. - 255 p.

2. Mastushkin, Yu.M. Means of active management of fishing vessels. / Yu.M. Mastushkin, E.M.Shesternenko. - M .: Agropromizdat, 1985 .-- 128 p.

3. Sobolev, G.V. Controllability of the ship and automation of navigation. / G.V.Sobolev. - L .: Shipbuilding, 1976 .-- 478 p.

4. Reference on the theory of the ship: In 3 vols. T.3. Manageability of displacement vessels. Hydrodynamics of vessels with dynamic principles of maintenance. / ed. J.I. Voytkunsky. - L .: Shipbuilding, 1985 .-- 544 p.: Ill.

5. Yudin, Yu.I. The theoretical basis of safe maneuvering when performing point mooring. / Yu.I. Yudin, S.V. Pashentsev, G.I. Martyuk, A.Yu. Yudin. - Murmansk: Publishing House of MSTU, 2009. - 152 p.

Claims (1)

A method for determining the transverse hydrodynamic force generated on the hull of a vessel during complex maneuvering, characterized in that before performing complex maneuvering, the vessel rotates under the influence of active control means, for example, a thruster, and the angular velocity of the vessel ω is measured and torque is calculated M_prformed by the thruster:
M_pr= T_epr× x_pr,
where T_epr - thruster thrust; x_pr - thruster abscissa
using values of angular velocity ω and torque M_pr determine the value of the hydrodynamic coefficient:
c₂= 29.645M_pr/ (ω²L^fourpd)
where L is the length of the vessel; d is the average draft of the vessel,
then find the magnitude of the transverse component of the hydrodynamic forceY _βformed on the hull of the vessel when it moves with a lag:
Y_β= C_yβ0,5ρυ²F_dp,
where c_yβ is the coefficient of the transverse component of the hydrodynamic force and C_yβ≅c₂; ρ is the mass density of water; υ is the linear speed of the vessel; F_dp - the reduced area of the diametrical buttocks of the vessel.