Thrusters
Dynamics of Propeller Blade and Duct Loadingon Ventilated Thrusters in Dynamic Positioning Mode
Kourosh KoushanMARINEK
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October 9-10, 2007Return to Session DirectoryReturn to Session Directory
1MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Dynamics of Propeller Bladeand Duct Loadings on Ventilated Thrusters
in Dynamic Positioning Mode
Kourosh [email protected]
MARINTEKNorwegian Marine Technology Research Institute
2MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Propeller and thruster models
Open thruster Ducted thruster
3MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Test set-up for ducted thruster tests
4MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Test set-up for open thruster tests
Electric motor
6 component balance
MC-Lab rig
Measurement blade
Pulse meter
5MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Tested parametersAll tests
Different propeller rate of revolutionsSpeed (negative, zero and positive)
Constant immersion testsDifferent immersion ratiosDifferent azimuth angles
Dynamic azimuthing testsDifferent immersion ratios
Dynamic vertical motion testsDifferent starting immersion ratiosDifferent amplitudesDifferent periods
6MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Open thruster; funnel centre on water surfaceh/R = 2.6 (constant immersion)
7MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Open thruster;shaft immersion ratio at highest position h/R=−0.15, amplitude/R=2.15, period=2s
(a) h/R=−0.15+0 amplitude/R=−0.15 (b) h/R=−0.15+0.14 amplitude/R=0.15 (c) h/R=−0.15+0.22 amplitude/R=0.31
(d) h/R=−0.15+0.33 amplitude/R=0.56 (e) h/R=−0.15+0.44 amplitude/R=0.79 (f) h/R=−0.15+0.66 amplitude/R=1.28
(g) h/R=−0.15+0.76 amplitude/R=1.48 (h) h/R=−0.15+0.84 amplitude/R=1.66 (i) h/R=−0.15+1 amplitude/R=2
8MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Continued…
Open thruster;shaft immersion ratio at highest position h/R=−0.15, amplitude/R=2.15, period=2s
(j) h/R=−0.15+0.97 amplitude/R=1.95 (k) h/R=−0.15+0.86 amplitude/R=1.7 (l) h/R=−0.15+0.77 amplitude/R=1.5
(m) h/R=−0.15+0.66 amplitude/R=1.26 (n) h/R=−0.15+0.56 amplitude/R=1.07 (o) h/R=−0.15+0.34 amplitude/R=0.58
(p) h/R=−0.15+0.24 amplitude/R=0.37 (q) h/R=−0.15+0.14 amplitude/R=0.15 (r) h/R=−0.15+0 amplitude/R=−0.15
9MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Ducted thruster;shaft immersion ratio at highest position h/R=−0.08, amplitude/R=1.8, period=4s
(a)
h/R=0.08+0 amplitude/R=0.08 (b)
h/R=0.08+0.3 amplitude/R=0.62 (c)
h/R=0.08+0.52 amplitude/R=1.02(d)
h/R=0.08+0.8 amplitude/R=1.52
(e)
h/R=0.08+0.92 amplitude/R=1.74(f)
h/R=0.08+1 amplitude/R=1.88 (g)
h/R=0.08+0.81 amplitude/R=1.54(h)
h/R=0.08+0.6 amplitude/R=1.16
(i)
h/R=0.08+0.5 amplitude/R=0.98 (j)
h/R=0.08+0.39 amplitude/R=0.78(k)
h/R=0.08+0.19 amplitude/R=0.42(l)
h/R=0.08+0.1 amplitude/R=0.26
10MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Open thruster; Relative blade thrustmin. h/R=-0.15; amplitude/R=2.15; T=2 s
11MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Open thruster; Low pass filtered blade thrust; min. h/R=-0.15; amplitude/R=2.15; T=2 s
12MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Open thruster; Shaft freq. fluctuations in blade thrust; min. h/R=-0.15; amplitude/R=2.15; T=2s
13MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Ducted thruster; Relative blade thrustmin. h/R=0.08; amplitude/R=1.8; T=4 s
0 2 4 6 8 10 12 14 16-2
-1
0
1
2
3
4Fx
/ave
rage
(Fx)
Fx/Average(Fx)
0 2 4 6 8 10 12 14 16
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Time(s)
h/R
h/R
14MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Ducted thruster; Low pass filtered blade thrust; min. h/R=0.08; amplitude/R=1.8; T=4 s
4 5 6 7 8 9 10 11 120
0.5
1
1.5
2
2.5
3Fx
/ave
rage
(Fx)
Fx/Average(Fx)
4 5 6 7 8 9 10 11 12
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Time(s)
h/R
h/R
15MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Ducted thruster; Shaft freq. fluctuations in blade thrust; min. h/R=0.08; amplitude/R=1.8; T=4 s
4 5 6 7 8 9 10 11 12-1.5
-1
-0.5
0
0.5
1
1.5Fx
/ave
rage
(Fx)
Fx/Average(Fx)
4 5 6 7 8 9 10 11 12
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Time(s)
h/R
h/R
16MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Time-averaged ducted thruster loadings under constant immersion
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.5 1.0 1.5 2.0 2.5h/R
Duct_X / Duct_X0Total_thrust/Total_Thrust0FX / FX0MX / MX0out-of-water factor
17MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Comparison of time-averaged loadings of ducted & open thrusters under constant immersion
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.0 0.5 1.0 1.5 2.0 2.5h/R
Total_Thrust / Total_Thrust0 (Ducted prop.)FX / FX0 (Ducted prop.)FX / FX0 (Open prop.)out-of-water factor
18MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Time-averaged ducted thruster loadings under forced heave motion
0
0.2
0.4
0.6
0.8
1
-1 -0.5 0 0.5 1h/R at highest position
out-of-water factorAverage FX/FX0Average MX/MX0Average Total_Thrust/Total_Thrust0Average Duct_X/Duct_X0
19MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Time-averaged relative blade thrust of open thruster under forced heave motion
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-1 -0.5 0 0.5 1 1.5 2 2.5h/R at highest position
Average FX/FX0out-of-water factor
20MARINTEKK. Koushan - Dynamic Positioning Conference 2007
Dynamics of Propeller Blade and Duct Loadings on Ventilated Thrusters in Dynamic Positioning Mode
Concluding remarks
Fluctuations in blade thrust and blade torque are quite significant when a thruster is ventilated.Ventilation influences both the dynamic and static loadings.More ventilation leads to less available blade thrust, blade torque, duct thrust and consequently total thrust.Under ventilated conditions, fluctuations in blade torque are almost identical to fluctuations in blade thrust.Loading fluctuations due to ventilation must be taken into account at the design stage.
