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Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA PowerPoint PPT Presentation


Trawl gear design to improve the energy efficiency using computer aided method. Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA. Issues related energy use in Fisheries. Increased focus related to the environmental impacts

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Chun-Woo LEE Division of Marine Prodution System Management Pukyong National University, Busan, KOREA

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Trawl gear design to improve the energy efficiency using computer aided method

Chun-Woo LEE

Division of Marine Prodution System Management

Pukyong National University, Busan, KOREA


Issues related energy use in Fisheries

  • Increased focus related to the environmental impacts

  • Achieve sustainable management of natural resources

    • Main aim of Kyoto protocol

  • Responsible Fishing (Cancun, Mexico in 1992)

  • Financial difficulties in fishing industries


Factors affect the energy consumed

  • Distance to the fishing ground

  • Searching for fish school

  • Operation of the fishing gear, Preservation of the catch

  • Current researches related to reducing the CO2 emission from fisheries

Fishing vessel

Operation

Design of fishing gears


Numerical Method

Numerical approach

  • is an economical way to predict the results.

  • provides the alternative plans to approach to the reality.

  • includes the uncertainty in the results.

Process

  • Establishing the numerical model

  • Computing the model

  • Analysis of hydrodynamic forces on the gear

  • Improve design by changing structure or materials


Numerical Modeling

  • Physical features of the structures

    • Consists of various materials

    • Exposed to various loads

    • Deforms to a considerable degree in the current and waves

    • Non-linearity

  • Difficulty to describe the mathematical model due to the environmental factors

  • Derive the non-linear and stiff equation


Mass spring model

Modeling of fishing gear


Modeling of Netting

Mesh grouping

  • Placement of virtual mathematical mesh using mesh grouping method and vector notation of the element.


Equation of motion

Internal Force

External Force

Added mass & Added mass coefficient


Hydrodynamic force

Resultant Velocity Vector

Drag and Lift Force

Unit Vector for Lift Force

Volume of Net

Buoyancy and Sinking


Drag coefficient in connection with ReD & Attack angle


Lift coefficient in connection with Attack angle


Numerical methods – Newmark- β

Governing equation of motion and Numerical methods

  • The position

  • The velocity

  • The acceleration

  • The relative error


Flow chart of the design and simulation using a computer


Trawl design plan and simulation


Database for designing fishing gears


Trawl design plan and simulation

  • Mid-water Trawl net in front view

  • Mid-water Trawl net in 3D view


Trawl design plan and simulation

  • Pair Trawl net in 3D view

  • Multi Trawl net in 3D view


Purse seine design and simulation tool


Simulation of a purse seine

Shooting process of purse seine net

Pursing process of purse seine net


Design of the gear using a computer


Analysis of the resistance on the gear

Tension (kgf)

Simulation condition

Section 1

372.92

  • Towing speed: 4 [kn]

  • Net part divided into 4 parts for analyzing the resistance

  • Changing the thickness:

    2/3, 1/3 times with Dyneema

Section 2

1496.14

Section 3

436.91

Section 4

5474.54

7735.51

Total


Comparison 1

Distance between Otterboards

[m]

Area of net mouth

[m2]

  • Changed section : section 4

Tension[kgf]

Height[m]

Top view

Side view

28.88

104.51

666.86

7735.51

2/3 times

1832.07

128.20

5565.39

42.38

Applied Dyneema in section 4 with reducing a thickness

1/3 times

2531.81

137.54

5009.83

53.09


Comparison 2

Distance between Otterboards

[m]

Area of net mouth

[m2]

  • Changed all sections

Tension[kgf]

Height[m]

Top view

Side view

104.51

28.88

666.86

7735.51

2/3 times

119.48

1448.30

6206.47

36.07

Applied Dyneema in all sections with reducing

a thickness

1/3 times

3069.71

143.13

4639.89

63.71


Construction costs

  • Calculated netting materials excluded rigging parts

  • Rigging parts will be necessary to adjust for appropriated shape of a gear

Construction costs

11

6

2.7

1

2

Applied Dyneema with reducing a thickness


: Resistance of a gear

E.H.P : Effective horse power

: Resistance of a vessel

: Relative current speed pass through a vessel

Fuel consumption & reduction

Fuel reduction ratio with changing the thickness of ropes compared to present type of the gear


Numerical Method

Discussion

  • can calculate the drag force on fishing gear under various conditions

  • can determine the material costs to build fishing gear

  • can make it possible to design an optimum fishing gear by balancing increased costs and reduced drag forces

  • will help design low-carbon emission fishing gear by saving both time and cost


Thank you for your attention !!


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