hydrodynamic aspects of the air lifted vessel (alv) presenter: nan xie supervisor: prof. dracos...
TRANSCRIPT
Hydrodynamic aspects of the Air Lifted Vessel (ALV)
Presenter: Nan Xie
Supervisor: Prof. Dracos Vassalos
SSRC, NA-ME
1 The Project - EFFISES
• 5th Framework Program of EU• 13 partners from 9 EU-countries
• Super high speed marine transportation• Objectives:
• Passenger ship: E40, 70kn• Cargo ship: E125,50kn
• Efficient – less power, 25%
• Environment friendly – less emission & wash
• Safe
SSRC’s task
• Development of methods & tools
• Wash Wave
• Stability
2 Prediction of Wash Wave of ALV
• Features: • Over 80% of vessel weight are supported by
air-cushion• Pressure patch distribution over cushion • Linear potential theory• New numerical scheme
• Results:
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
-4 -3 -2 -1 0 1 2 3 4
x/a
Non
-dim
ensi
onal
free
sur
face
Present
Kim [8]
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 1 2 3 4 5 6 7 8y/L
Hm
(m)
Fn=0.5
Fn=1.0
Fn=1.5
Fn=2.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0y/L
ln(E
) E(K
J/m
) Fn=0.5
Fn=1.0
Fn=1.5
Fn=2.0
3 Stability study
• Features: • Air compressibility in cushion• Non-linear equations of motions• Time domain simulation• Impulse response function & memory effects • Case study
Results – Free surface elevation
Fn=0.50, Tao=0.275
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
-4 -3 -2 -1 0 1 2 3 4
x/a
Non
-dim
ensi
onal
fre
e su
rfac
e
Re, present
Re, Doctors'
Im, present
Im, Doctors'
b/a=0.156, Fn=0.72
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
0 2 4 6 8 10 12 14 16 18 20
sigma*(L/g)**0.5
No
n-d
imen
sio
nal
esc
ape
volu
me
Re, present
Re, Nakos'
Im, present
Im, Nakos'
EFFISES E_40, Fn=1.50
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
0 10 20 30 40 50 60
sigma*(L/g)**0.5
non-
dim
ensi
onal
free
sur
face
Re, y/L=0.289
Im, y/L=0.289
EFFISES, Fn=2.0
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0 10 20 30 40 50 60 70
sigma*(L/g)**0.5
Non
-dim
ensi
onal
esc
ape
volu
me
Re
Im
Results - Impulse response function
EFFISES E_40, Fn=1.50
-2.50E-04
-2.00E-04
-1.50E-04
-1.00E-04
-5.00E-05
0.00E+00
5.00E-05
1.00E-04
0.0 0.5 1.0 1.5 2.0 2.5 3.0
t (s)
hz (
m/p
a.s)
y/L=0.211
y/L=0.226
EFFISES E_40, Fn=1.50
-3.00E-02
-2.50E-02
-2.00E-02
-1.50E-02
-1.00E-02
-5.00E-03
0.00E+00
5.00E-03
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
t (s)
hv (
m^3
/pa.
s)
Results - Porpoising
13.5
14.5
15.5
16.5
17.5
18.5
19.5
20.5
21.5
0.80 0.85 0.90 0.95 1.00 1.05 1.10
cushion height (m), Qin0=75m^3/s
Xg
(m, m
easu
red
from
ste
rn) stable
unstable
12.0
13.0
14.0
15.0
16.0
17.0
18.0
19.0
20.0
20 40 60 80 100 120
fan inflow rate (m^3/s), cushion heright=0.9m
Xg,
(m
, mea
sure
d fr
om s
tern
)
stable
unstable
Qin0=50m^3/s, Vs=55knot, E40
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0 10 20 30 40 50
time in second
heave, mQin0=37.5m^3/s, Vs=55knot,E40
-0.06
-0.04
-0.02
0.00
0.02
0.04
0.06
0.08
0 5 10 15 20
time in second
heave, m
4 Outcomes:
• Project deliverables• Paper for ISOPE’04• Paper for PRADS’04
5 Future Works
• Wash wake assessment of ALV
• Refinement of mathematic model of stability• 6 DOF • Stability in manoeuvring motion• CFD – dynamic force derivates
• Design & operational guideline, safety assessment
Acknowledgments