US 11,768,126 B2 · Method of ship ice resistance model experiment based on non-refrigerated model ice

Abstract

The present disclosure discloses a method of ship ice resistance model experiment based on non-refrigerated model ice, including the following steps: determining the overall length L1, breadth B and scale ratio λ of a selected ship model; determining the size A1 of an experimental area for placing broken ice in the ship ice resistance model experiment; determining the characteristic length of model ice; determining the quantitative proportion of the model ice for each size under the target coverage ratio c of the model; obtaining the number of the model ice for each size under the target coverage ratio according to the quantitative proportion of the model ice for each size under the target coverage ratio c and the total area A2 of the model ice; determining the geometrical shape and parameters of each size under the target coverage ratio c of the model ice. The present disclosure solves the problems of poor economy and poor operability in a freezing model ice experiment of an ice basin, and provides a design method for carrying out a ship ice resistance model experiment in a towing tank.

A method of ship ice resistance model experiment based on non-refrigerated model ice, comprising the following steps:

S1. determining an overall length L1, a breadth B, and a scale ratio λ of a selected ship model;
determining a size A1 of an experimental area for placing broken ice in the ship ice resistance model experiment:
according to the overall length L1 and the breadth B of the selected ship model, determining the minimum size of the experimental area, further determining the size of the experimental area:
L2≥5L1,
W≥3B,
A1=WL2,
wherein, L2 represents a length of the experimental area, and W represents a width of the experimental area;
S2. determining a characteristic length of model ice:
S21. determining a target coverage ratio c of the model ice;
S22. according to the experimental area size A1 obtained in step S1 and the target ice coverage ratio c obtained in step S21, determining a total area A2 of the model ice:
A2=cA1;
S23. according to the bending theory of thin plate sitting on elastic foundation, determining a critical characteristic length Lc of the broken ice without bending failure:
L
c
=
D
k
4
,
wherein, D represents a flexural rigidity of ice, satisfying the following equation:
D
=
Et
3
12
⁢
(
1
-
v
2
)
,
E represents an elastic modulus of ice, with the unit of Pa;
t represents an actual thickness of the broken ice, with the unit of m;
v is Poisson's ratio;
and k represents an elastic stiffness of the base, satisfying the following equation:
k=ρwg,
ρw is the density of water, with the unit of kg/m3;
and g is the acceleration of gravity, with the unit of kg/m2;
S24. determining the critical characteristic length l:
l
=
L
λ
,
wherein, L represents a characteristic length of the broken ice, satisfying the following condition:
L≤Lc;
S25. according to the critical characteristic length l of the model ice, determining a characteristic length ln of each size of the model ice in the ship ice resistance model experiment;
S3. determining a quantitative proportion of the model ice for each size under the target coverage ratio c of the model ice:
N
⁡
(
l
n
)
=
{
β
1
⁢
l
n
-
α
1
,
l
n
∈
[
1
,
40
]
β
2
⁢
l
n
-
α
2
,
l
n
∈
[
40
,
1500
]
wherein, N(ln) represents a number of the model ice with the size ln, α1, a2, β1 and β2 are coefficients, α1=1.15, α2=1.87;
when the characteristic length ln of the model ice is in a range of [l1,l2], the total area of the model ice satisfies the following equation:
A
=
∫
l
2
l
1
⁢
n
a
⁡
(
x
)
⁢
s
⁡
(
x
)
⁢
dx
=
-
πβα
4
⁢
(
α
-
2
)
·
(
l
2
(
-
α
+
2
)
-
l
1
(
-
α
+
2
)
)
,
solving the following set of equations to obtain β1 and β2,
{
cA
=
∫
1
1500
⁢
n
a
⁡
(
x
)
⁢
s
⁡
(
x
)
⁢
dx
,
A
=
1
⁢
km
2
β
1
⁢
l
-
α
1
=
β
2
⁢
l
-
α
2
,
l
=
40
⁢
m
;
S4. according to the quantitative proportion of the model ice of each size under the target coverage ratio c obtained in step S3, and the total area A2 of the model ice to obtain the number of the model ice of each size under the target coverage ratio c;
and
S5. determining a geometrical shape and parameters of the model ice for each size under the target coverage ratio c:
a roundness R of the model ice satisfies the following equation:
R
=
d
p
d
=
P
π
l
n
=
P
π
⁢
l
n
;
wherein, dp represents a perimeter-equivalent diameter, d represents a area-equivalent diameter, and d is equal to ln, P represents a perimeter of geometrical shape of the model ice;
an area S of the geometrical shape of the model ice satisfies the following equation:
S
=
π
⁢
l
n
2
4
;
a caliper diameter ratio Ra of the model ice satisfies the following equation:
Ra=Dmax/Dmin;
determining P according to the value of R;
determining the geometrical shape of the model ice according to P, S, and Ra.

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Method of ship ice resistance model experiment based on non-refrigerated model ice

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Method of ship ice resistance model experiment based on non-refrigerated model ice

Life of this patent

Abstract

Claims3