RU2033370C1 - Method of check of ship's stability - Google Patents

Abstract

FIELD: shipbuilding. SUBSTANCE: the following parameters are measured: rolling period, drafts fore and aft, period of encounter, relative bearing, ship's running speed, period of oscillatory motion of ship relative to transverse central axis and stress acting amidships in section being checked on upper deck, port and starboard. EFFECT: enhanced reliability. 2 dwg

Description

 The invention relates to the field of shipbuilding, in particular to methods for monitoring the stability of a vessel under operating conditions, and can be used to create navigation expert systems.

 A known method of stability control, based on measuring the rolling period and determining the calculation of metacentric height, the calculation of which additionally measure precipitation with bow and stern, the apparent wave period, heading angle and speed of the vessel on an irregular wave. The disadvantage of this method is the low reliability of monitoring the safety of the vessel in extreme situations, especially during sharp rolling and intense dynamic loads on the hull.

 The purpose of the invention to increase the reliability of assessing the safety of operation of the vessel.

 The inventive measure the period of oscillation of the vessel relative to the transverse central axis and stresses acting on both sides of the upper deck in the plane of the midsection.

 In FIG. 1 presents a structural and functional diagram of a device that implements the proposed method; in FIG. 2 scheme for choosing the optimal heading angle.

 The method of monitoring the stability of the vessel is as follows.

 The directional angle of the wave, the speed of the vessel, the draft with bow and stern are measured, and at the same time, the periods of oscillation of the vessel relative to the longitudinal and transverse central axes and the stresses acting on the sides of the upper deck in the midship plane are recorded.

W, (1) где h_кр критическая метацентрическая высота;
σ и σ_кр фактическое и допустимое напряжения; W=(0,7-1,3) τ_θ или (0,7-1,3) τ_Ψ; τ_θ и τ_Ψ периоды бортовой и килевой качки судна;
область допустимого изменения курсового угла волны φ_доп= φ ±15^о, внутри которой выделяют зоны неблагоприятных курсовых углов, определенных условиями (1);
метацентрическую высоту h(φ), действующие напряжения σ (φ) и полное гидродинамическое сопротивление R(φ) в диапазоне φ_доп

, (2) где f₁(φ)=а₁+а₂ φ²+а₃ φ³+а₄ φ⁴+а₅φ ⁵+а₆φ ⁶;
f₂(φ)=b₁φ ²+b₂φ ³+b₃φ ⁵+b₄ φ⁶+b₅ φ⁷+
+b₆φ ⁹;
f₃( φ)=c1φ* +с₂(φ*)³+c₃(φ*)⁴+ с₄(φ*)⁵+
+ с₅(φ*)⁶+с₆(φ*)⁹˙[1+f(κ_R)][1+f(κ_q)] а₁=-0,13, а₂=-0,29, а₃=0,50, а₄=-0,10, а₅=0,006, а₆=-0,002; b₁=-1,58, b₂=1,03, b₃=-0,061, b₄=-0,03, b₅=0,013, b₆=-0,00027; c₁=3,34, c₂=-2,60, c³=0,54, c₄=0,19, c₅=0,0402, c₆=-0,0048; φ=0 соответствует движению судна на попутном волнении, а φ*=0 на встречном волнении; при φ*= 3 π/2- π f₃(φ)=f₃(φ*=3 π/2)=const; σ₁ и σ₂ напряжения от общего изгиба корпуса на волнении, установленные при положении судна вразрез волнам и лагом к волнению; f(κ_R)=3(κ_R-0,9); κ_R=(1,2-0,1 α^1/2)-(2,9 α^1/2-1,9)Fr; Fr= V/(gL)^1/2; g ускорение свободного падения; L длина судна; f(κ_q)= -1,05q*+0,78(q*)²; q*=q-0,3; q=q_o(10h_3%/L); q_o=1,0 для развитого, q_o= 0,7 для развивающегося и q_o=1,5 для волнения зыби; h_3% высота волны 3%-ной обеспеченности; R_о сопротивление судна на тихой воде; Δ R дополнительное сопротивление на встречном волнении; α коэффициент полноты ватерлинии;
оптимальные значения курсового угла φ_орt и скорости судна V_орt, соответствующие минимуму полного гидродинамического сопротивления на участке φ_доп (при отсутствии указанного минимума принимают наименьшую величину сопротивления за пределами выделенных по условиям (1) зон неблагоприятных курсовых углов), где V_opt=V+ Δ V; V скорость; Δ V=[(R/R*)^1/3-1] приращение скорости, вызванное снижением сопротивления; R и R* значения сопротивления при курсовых углах φ и φ_opt.According to the measurements establish:
displacement, apparent period and actual metacentric height and assess the situation by comparing the actual indicators of stability, pitching and strength with acceptable values under the conditions:
h <h _cr , σ> σ _cr ,

W, (1) where h _cr critical metacentric height;
σ and σ _{cr the} actual and allowable stress; W = (0.7-1.3) τ _θ or (0.7-1.3) τ _Ψ ; τ _θ and τ _Ψ periods of rolling and pitching of the vessel;
the area of permissible change in the directional angle of the wave φ _add = φ ± 15 ^about , inside which there are zones of unfavorable course angles defined by conditions (1);
metacentric height h (φ), acting stresses σ (φ) and total hydrodynamic resistance R (φ) in the range φ _add

, (2) where f ₁ (φ) = a ₁ + a ₂ φ ² + a ₃ φ ³ + a ₄ φ ⁴ + a ₅ φ ⁵ + a ₆ φ ⁶ ;
f ₂ (φ) = b ₁ φ ² + b ₂ φ ³ + b ₃ φ ⁵ + b ₄ φ ⁶ + b ₅ φ ⁷ +
+ b ₆ φ ⁹ ;
f ₃ (φ) = c1φ * + s ₂ (φ *) ³ + c ₃ (φ *) ⁴ + s ₄ (φ *) ⁵ +
+ s ₅ (φ *) ⁶ + s ₆ (φ *) ⁹ ˙ [1 + f (κ _R )] [1 + f (κ _q )] a ₁ = -0.13 and ₂ = -0.29 , and ₃ = 0.50, and ₄ = -0.10, and ₅ = 0.006, and ₆ = -0.002; b ₁ = -1.58, b ₂ = 1.03, b ₃ = -0.061, b ₄ = -0.03, b ₅ = 0.013, b ₆ = -0.00027; c ₁ = 3.34, c ₂ = -2.60, c ³ = 0.54, c ₄ = 0.19, c ₅ = 0.0402, c ₆ = -0.0048; φ = 0 corresponds to the movement of the vessel in the case of passing waves, and φ * = 0 for the oncoming waves; when φ * = 3 π / 2- π f ₃ (φ) = f ₃ (φ * = 3 π / 2) = const; σ ₁ and σ ₂ stresses from the total bending of the hull on the waves, set when the vessel is in position against the waves and the lag to the waves f (κ _R ) = 3 (κ _R -0.9); κ _R = (1.2-0.1 α ^1/2 ) - (2.9 α ^1/2 -1.9) Fr; Fr = V / (gL) ^1/2 ; g acceleration of gravity; L ship length; f (κ _q ) = -1.05q * + 0.78 (q *) ² ; q * = q-0.3; q = q _o (10h _3% / L); q _o = 1.0 for the developed, q _o = 0.7 for the developing and q _o = 1.5 for the excitement of swell; h _3% wave height 3% security; R _{about the} resistance of the ship in quiet water; Δ R additional resistance to oncoming waves; α waterline completeness coefficient;
the optimal values of the heading angle φ _ort and the vessel speed V _ort , corresponding to the minimum of the total hydrodynamic resistance in the section φ _add (in the absence of the specified minimum, the least resistance is taken outside the zones of unfavorable heading angles selected according to conditions (1)), where V _opt = V + Δ V; V speed; Δ V = [(R / R *) ^1/3 -1] the increment of speed caused by a decrease in resistance; R and R * are resistance values at course angles φ and φ _opt .

 The device contains sensors for heading angle 1 and speed of the vessel 2, the values of which are entered into the computer 10 using the display 11, sensors for periods of oscillatory movement of the vessel relative to the longitudinal 3 and transverse 4 central axes, pressure sensors 5 and 6, characterizing the draft of the vessel with bow and stern, sensors voltage on the right 7 and left 8 sides of the upper deck in the midship plane, the signals from which are fed to the input of the program-control module 9 for converting the initial information and entering it into a computer 10 with a color graphic display 11 and a printer 12.

Claims (1)

 METHOD OF CONTROL OF STABILITY OF A SHIP, characterized in that, in order to increase the reliability of assessing the safety of operation of a ship, they additionally measure the period of oscillation of the ship relative to the transverse central axis and the stresses acting on the sides of the upper deck in the midship plane.

Images