A trawl door with an additional, controlled foil.

Collaboration diagram for Trawl door with foil:

Author: Karl-Johan Reite

Date: 09.01.2014 KJR: Initial version.

0004 — TrawlDoorAddedFoil discards its computed foil force and applies a hard-coded roll moment

0005 — TrawlDoorAddedFoil FoilEnergyConsumed output is always zero

0006 — TrawlDoorAddedFoil interpolates the foil polar with the wrong array length

This simObject represents a trawl door with an additional, controlled foil. It is meant for testing proposed control concepts. The foil geometry (cord, span) and its lift and drag coefficients for several angles of attack are configuration parameters; its angle of attack relative to the door, its exposed area ratio and its position in the door coordinate system are input ports.

The trawl door is simulated in six degrees of freedom. This model includes a fairly complex model of the hydrodynamic forces and the fastening points of the warp and the bridles. It is based on unit quaternions for translation between different coordinate systems, to avoid the singularity problem of Euler angles.

Example file input:

<Lib LibName                = "fishery"
    SimObject               = "Trawl/TrawlDoorAddedFoil"
    Name                    = "door"
        />

Configuration parameters

Name	Width	Description
FoilHydro_Aoa	<HydroSpecWidth>	The foil angle of attack relative to the water flow.
FoilHydro_CL	<HydroSpecWidth>	The foil lift coefficient for the specified angles of attack in FoilHydro_Aoa.
FoilHydro_CD	<HydroSpecWidth>	The foil drag coefficient for the specified angles of attack in FoilHydro_Aoa.
FoilHydro_IsVertical	1	Is the foil vertical? Otherwise it is assumed horizontal (in relation to the trawl door).
FoilHydro_Cord	1	The foil cord.
FoilHydro_Span	1	The foil span.

Input Ports

Name	Width	Description
FoilRelativeAoa	1	The foil angle of attack relative to the door.
FoilExposedAreaRatio	1	The ratio of the foils area which is exposed.
FoilRelPosition	3	The position of the foil in the trawl door coordinate system.

Output Ports

Name	Width	Description
FoilEnergyConsumed	1	The energy consumed by controlling the foil.

Initial conditions

Position, orientation

This SimObject is referred to as Trawl/TrawlDoorAddedFoil