SLIDE 1 SAB Meeting – LA SPEZIA February 2018
Master thesis presentation
Blade bulbous-bow concept application research using commercial CFD software
Author: Mukhitdin Kakenov Supervisor: Prof.Dario Boote, University of Genova
SLIDE 2 SAB Meeting – LA SPEZIA February 2018
- Previous education: Saint-Petersburg State Marine
Technical University (SMTU)
- Field of interest: Seakeeping; Hull Optimization; Ship
Theory; Safe Operation of a ship, marine technologies in maritime area
- Seeking Career & objectives: Naval Designer, Project
Engineer, Research Engineer in hull form and ship structure optimization study branches.
Mukhitdin KAKENOV Kazakhstan Marine Engineer
SLIDE 3 Example 1. Benetti’s F-125
http://www.charterworld.com/news/f125-yacht-hull-arrives-benetti-yard-italys-viareggio
SLIDE 4
F-125
SLIDE 5 F-125
Length on waterline – 31.0 meters Maximum beam – 8.23 meters Half load draught – 2.01 meters High-speed range – 17.5-22 knots
https://www.pressreader.com/italy/superyacht/20170109/282428463876372
SLIDE 6 F-125. Now how it looks on a serial ship:
https://sandpeoplecommunication.wordpress.com/2013/12/16/benetti-news-from-the-yard-november- december-2013
SLIDE 7 Next example: ILUMEN 28M
http://robbreport.com/motors/marine/dominators-ilumen-now-more-spacious-and- preparing-launch-231479/
SLIDE 8 ILUMEN 28M
Length on waterline – 28 meters Maximum beam – 8.23 meters Half load draught – 1.85 meters High-speed range – 17-29 knots
https://www.superyachttimes.com/yacht-news/dominator-ilumen-28m-taking- shape-in-italy
SLIDE 9 ILUMEN 28M in towing tank
https://www.pressreader.com/italy/superyacht/20170109/282428463876372
SLIDE 10
ILUMEN 28M in towing tank
SLIDE 11 ILUMEN 28M in towing tank
TOTAL RESISTANCE – pay attention on this! Which force component had been mostly reduced?
SLIDE 12 The Object of Interest
Rhinoceros software was used to build the model of the yacht
SLIDE 13
The Object of Interest
SLIDE 14
The Object of Interest
General arrangements and some technical information: LengthPP 54.2 m Breadth 12.6 m Designed draught 3.3 m Velocity range up to 22 kn
SLIDE 15 CFD
[Star-CCM+ CFD software was chosen]
- Set rules of physics
- Change a flow as ever you want
- Change a ship and an experimental
domain models so many times as you need
SLIDE 16 What mesh size is better? Calculation quality vs. Time spent
The lower the cell size the more accurate the results of simulation
*Image has been taken from the Star-CCM+ 11 ver. manual
HOWEVER: the lower the cell size, the longer the time spent to compute a
- problem. Where is the golden middle???
SLIDE 17 Mesh convergence study
- Let’s define some geometrical parameter to use it as a
relative value: In Star-CCM+ it is a “Base size” argument
It’s a value, percentage of which may characterize an elemental size (length) of a computing cell
- How long should be this length? => any easy to operate
with setting different cells sizes
SLIDE 18 Mesh convergence study
- Let’s define some geometrical parameter to use it as a
relative value: In Star-CCM+ it is a “Base size” argument
It’s a value, percentage of which may characterize an elemental size (length) of a computing cell
- How long should be this length? => any easy to operate
with setting different cells sizes
SLIDE 19
Mesh convergence study
SLIDE 20 Mesh convergence study
19 21 23 25 27 29 31 13.5 14 14.5 15 15.5 16 16.5 17 17.5 Force, kN Velocity, knots
Shear drag, mesh convergence
Base 10 meters Base 7.5 meters Base 6 meters
SLIDE 21 Mesh convergence study
20 25 30 35 40 45 50 55 60 13.5 14 14.5 15 15.5 16 16.5 17 17.5 Pressure, kPa Velocity, knots
Pressure drag, mesh convergence
Base 10 meters Base 7.5 meters Base 6 meters
SLIDE 22 Mesh convergence study
- 0.31
- 0.29
- 0.27
- 0.25
- 0.23
- 0.21
- 0.19
- 0.17
- 0.15
13.5 14 14.5 15 15.5 16 16.5 17 17.5 Meters Velocity, knots
Sinkage, mesh convergence
Base 10 meters Base 7.5 meters Base 6 meters
SLIDE 23 Mesh convergence study
0.45 0.47 0.49 0.51 0.53 0.55 0.57 0.59 0.61 0.63 0.65 13.5 14 14.5 15 15.5 16 16.5 17 17.5 Degrees Velocity, knots
Trim, mesh convergence
Base 10 meters Base 7.5 meters Base 6 meters
SLIDE 24
Mesh convergence study
SLIDE 25
Mesh convergence study
SLIDE 26
Yacht with the bulbous bow
SLIDE 27
Yacht with the bulbous bow
SLIDE 28
Yacht with the bulbous bow
SLIDE 29 Yacht with the bulbous bow
Kelvin waves
SLIDE 30
Gathered reference DATA: Resistance components (17 knots)
SLIDE 31
Gathered reference DATA: ship motions (17 knots)
SLIDE 32 REFERENCE DATA COLLECTED
19 21 23 25 27 29 13.5 14.5 15.5 16.5 17.5 Force, kN Velocity, knots
Shear drag
25 30 35 40 45 50 55 13.5 14.5 15.5 16.5 17.5 Pressure, kPa Velocity, knots
Pressure drag
13.5 14.5 15.5 16.5 17.5 Meters Velocity, knots
Sinkage
0.45 0.5 0.55 0.6 0.65 13.5 14.5 15.5 16.5 17.5 Pressure, kPa Velocity, knots
Trim
SLIDE 33 Changing the bulbous bow to a blade one
- Features of the blade bow concept should be noticed:
Side view Front view Top view Bottom view
SLIDE 34
Blade bow. First design
SLIDE 35
Blade bow. First design
SLIDE 36
Blade bow. First design
SLIDE 37
Blade bow. First design
Bottom view
SLIDE 38
Blade bow, 1st design. Produced wave profile on 17 knots forwarding
SLIDE 39
17 knots
SLIDE 40
17 knots
SLIDE 41
17 knots. Blade bow
SLIDE 42 Changing the bulbous bow to a blade one
- Features of the blade bow concept should be noticed:
Side view Front view Top view Bottom view
SLIDE 43
Blade bow, 2nd variant
SLIDE 44
Blade bow, 2nd variant
SLIDE 45
17 knots. Blade bow, 2nd variant
SLIDE 46
17 knots. Blade bow, 2nd variant
SLIDE 47
17 knots. Blade bow, 2nd variant
SLIDE 48
17 knots. Blade bow, 2nd variant
SLIDE 49 Friction comparison
…
19 21 23 25 27 29 31 13.5 14 14.5 15 15.5 16 16.5 17 17.5 Resistance, kN Velocity, knots
Frictional resistance
Bulbous bow Blade bow 1 Blade bow 2, more inclined top
SLIDE 50 Pressure drag comparison
19 24 29 34 39 44 49 54 59 64 69 13.5 14 14.5 15 15.5 16 16.5 17 17.5 Pressure, kPa Velocity, knots
Pressure drag
Bulbous bow Blade bow 1 Blade bow 2, more inclined top
SLIDE 51 Sinkage comparison
- 0.4
- 0.35
- 0.3
- 0.25
- 0.2
- 0.15
13.5 14 14.5 15 15.5 16 16.5 17 17.5 Sinkage, meters Velocity, knots
Sinkage
Bulbous bow Blade bow 1 Blade bow 2, more inclined top
SLIDE 52 Trim comparison
0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 13.5 14 14.5 15 15.5 16 16.5 17 17.5 Trim, degrees Velocity, knots
Trim
Bulbous bow Blade bow 1 Blade bow 2, more inclined top
SLIDE 53 So, what do we have now…
- Trim had been changed (involving or
separately from the sinkage - ?)
- Pressure drag increased – in what areas
- f the bow?
- Frictional drag is almost the same
SLIDE 54 CONCLUSION
- The bow shape gives direct influence on ship motions
- behavior. Changing the bow we will change the trim and
sinkage, in particular;
- The pressure drag of the yacht’s new shape had been
increased – how to reduce it, modifying the bow? The new problem to future additional research;
- The blade bow does not function as the initial one – does
not help against wave producing effect. How to optimize the bow in connection to this aspect? This is a new problem appeared – to be studied in optimization study subject.
