Method for determination of crosswise hydrodynamic force and its moment in ship complex maneuvering

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.

The invention relates to controlling the trajectory of the vessel, performing complex maneuvers when mooring or dynamic positioning.

The purpose of the invention is the improved management of the vessel, performing complex maneuvers.

Improved management of the vessel, performing complex maneuvers can be achieved by predicting its movement by means of computer simulation using the mathematical model of the vessel.

The efficacy and safety of performing complex maneuvers depend on the availability of the necessary information to adequately assess the behavior of the vessel under the influence of internal or external control actions. As control actions in this case are considered impact in terms of forces and moments produced by the operation of propulsion and steering of the ship or propulsion and steering complexes auxiliary (external) management tools, such as tugs.

To predict the behavior of the vessel when performing difficult maneuvers in the control actions are impossible without determining the hydrodynamic parameters of the mathematical model, in particular the values of transverse hydrodynamic forces generated on the hull during its motion.

Due to the lack of the Oia relevant technical means of measurement of hydrodynamic forces, formed in hull during its movement, it is possible definition of calculation-experimental method.

There is a method of determining the hydrodynamic parameters of the mathematical model of the vessel (U.S. Pat. No. 2442718, publ. 20.02.2012).

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

linear velocities of the nasal F (υ_fand aft A (υ_andpoints and their projections on the longitudinal X (υ_xf, υ_ha) and transverse Y (υ_yf, υ_ya) coordinate axis of the coordinate system ZXOY associated with the vessel (see figure 1);

the abscissa of the center of rotation (x₀) in the coordinate system ZXOY;

projection of the vector of linear velocity at the center of gravity on the transverse axis Y (υ_y);

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

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

angular speed (ω);

which is used to calculate the current values of the hydrodynamic parameters of the mathematical is dressed ship, on the basis of which perform computer modeling to predict the motion of a vessel at high speed.

However, there are such kinds of maneuvering when predicting the motion of the vessel, there is no need to define all of the hydrodynamic parameters of the mathematical model, as stated above (U.S. Pat. No. 2442718), it is sufficient to determine only the value of the transverse component of the hydrodynamic forces generated on the hull during its motion. To the specified types of maneuvering should include mooring operations, dynamic positioning, the drift of the vessel. A distinctive feature of these maneuvers is that, drifting, performing mooring operation, positioning, vessel moves a lag angle values of drift in this range 90±20° [2], [3], [5]. This allows you to calculate the value of the transverse component of the hydrodynamic forces generated during movement of the vessel using only one dynamic parameter of the mathematical model of the vessel.

The objective of the proposed method is a significant decrease in the number of parameters of the mathematical model used to predict the motion of the ship in the process of maneuvering, and, consequently, reducing the likelihood of forecast errors and improving its reliability and quality.

The way Zack is udaetsya in the following. The value of the transverse component of the hydrodynamic forces generated on the hull of the vessel in its motion, is determined by the relationship:

$$Y_{\beta }=C_{y\beta }\mathrm{0,5}\rho {\upsilon }^2{F}_{dp},\left(\text{1}\right)$$

where C_yβ- the ratio of the transverse component of the hydrodynamic force;

ρ is mass density of water;

υ is the linear speed of the ship;

F_dp- the area diametrically buttock vessel.

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

$$C_{y\beta }=\mathrm{0,5}{c}_1\sin 2\beta \cos \beta +c_2\sin \beta \left|\sin \beta \right|+c_3{\sin }^{4}2\beta sign\beta ,\left(\text{2}\right)$$

here c₁c₂c₃hydrodynamic coefficients, determined by the calculation method and the known calculated dependences [4], thus the numerical value of the coefficient c₂higher values of the coefficients c₁c₃; β is the angle of drift.

From the expression (2) implies that the drift angles close to 90°, it may be replaced by dependence

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

The difference in values of the coefficient C_yβcalculated according to the formulas (3) and (2), in the range of drift angles of 90±20°is not more than 10%, which meets the accuracy requirements definition effort, formed in hull during its movement [2].

To determine the value of the transverse component of the hydrodynamic forces generated on the hull of the vessel when it is in motion, you can use the dependence (3), unknown hydrodynamic parameter which is only a factor c₂.

To determine the value of coefficient c₂it is necessary to rotate the hull under the influence of active management, such as thrusters.

Thus, the procedure for determining the values of the transverse component of the hydrodynamic forces generated on the hull during its movement lag is m, is the following. Before performing difficult maneuvers the ship complies with the rotation under the influence of active management, such as thrusters, commonly used to measure the angular speed ω and calculate the torque generated thruster

$$M_{pr}=T_{epr}\times x_{pr},\left(\text{4}\right)$$

where T_epr- thrust thrusters; x_prthe abscissa channel thrusters.

Using the values of the angular speed ω and torque M_prin accordance with the formula presented in [3], we calculate the value of the coefficient c₂

$$c_2=\mathrm{29,645}{M}_{pr}/\left({\omega }^2{L}^4\rho d\right),\left(\text{5}\right)$$

where L is the length of the vessel; d - mean draft of the ship.

On the basis of dependency (3), (1) find the magnitude of the cross with the bringing hydrodynamic forces, formed in hull during its movement lag.

Literature

1. Bassin, A.M. Propulsion and handling of ships. / Ammain. - M.: Transport, 1967. - 255 S.

2. Matushkin, Y.M. Means of active control of fishing vessels. / Umiastowski, Emerence. - M.: Agropromizdat, 1985. - 128 S.

3. Sobolev, GV Handling of ship automation and navigation. / Howable. - Leningrad: Sudostroenie, 1976. - 478 S.

4. Handbook of theory of ship: 3 so V.3. The controllability of the displacement vessels. Hydrodynamics of vessels with dynamic support. Ed. Aigosthena. - Leningrad: Sudostroenie, 1985. - 544 S.: ill.

5. Yudin, SCI Theoretical basics of safe ways of maneuvering when performing point mooring. / Wiggin, Savasana, Hearty, Ayuden. - Murmansk: Izd-vo MGTU, 2009. - 152 C.

The method for determining the transverse hydrodynamic forces generated on the hull of the vessel when performing difficult maneuvers, characterized in that before the execution of complex manoeuvring the vessel performs a rotation under the influence of active management, such as thrusters, commonly used to measure the angular speed ω and calculate the torqueM_prformed thruster:
M_pr=T_epr×x_pr,
where T_epr- thrust thruster device is a; x_prthe abscissa channel thrusters
using the values of the angular speed ω and torque M_prdetermine the value of the hydrodynamic coefficient:
c₂=29,645M_pr/(ω²L⁴pd),
where L is the length of the vessel; d - average draught of the vessel,
then find the magnitude of the transverse component of the hydrodynamic forceY_βformed in hull during its motion lag:
Y_β=C_yβ0,5ρυ²F_dp,
where C_yβ- the ratio 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 area diametrically buttock vessel.