Feature 4 | CAD/CAM
Optimisation of Energy Saving Devices using SHIPFLOW
Ship based CO2 emissions have been of increasing concern for many
years. Emissions are projected to grow despite market driven efficiency improvements which caused the International Maritime Organization (IMO) to develop measures to reduce the emissions within an agreed timetable.
T
he Energy Efficiency Design Indexing (EEDI) shall be adopted for the initial design phase of new
ships. Tis leads to greater demands for ship designers to develop more energy efficient hull and propulsion systems. SHIPFLOW can provide the designer with valuable tools for a better understanding and evaluation of
the ship design
alternatives. In addition to newbuildings requiring optimisation there is also great demand for retrofitting existing ships. In some cases it is to improve their efficiency and in other situations to improve their operational characteristics. One distinguishing feature of
SHIPFLOW is its specialisation for ship design. It provides automatic grid generation and configuration of the flow solvers. Besides the direct advantages for the users it also makes it well suited for integration with CAD/CAM and optimisation soſtware - a key factor when it comes to reducing the lead time of design projects. Te SHIPFLOW FRIENDSHIP Design Package is an integration of the CFD soſtware SHIPFLOW and the computer aided engineering (CAE) software FRIENDSHIP-Framework. The software is tightly coupled which means that the user can configure, run and post-process the SHIPFLOW grid generators and flow solvers directly from the FRIENDSHIP-Framework. Te automatic grid generation capabilities will be inherited and allows a full utilisation of the optimisation capabilities in the FRIENDSHIP-Framework. Te ship can be defined using both fully and partial parametric modelling. In the first case the ship can be defined by key parameters such as
ship dimensions, volume
entrance angles. The latter case uses a conventional hull definition as the base and only the changes are parametised.
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Figure 1: Surface grids for duct and fins.
Variants of the ship are easily generated and the technique is well suited for shape optimisation. Te designer can control the variants by defining form parameter, constraint and dependencies. Systematic variations or automatic optimisation can then be applied to search for the best design. Te tight integration provides a unified graphical user interface for the configuration, running the simulation and managing the variants. As a standard, SHIPFLOW Design
is provided to customers purchasing only SHIPFLOW.
SHIPFLOW Design
is a subset of the FRIENDSHIP- Framework and provides a graphical user interface and variant managements
to the CFD solver. However, it does not contain the parametisation capabilities and optimisation tools
that the full
FRIENDSHIP-Framework does. The overlapping grid capability in
SHIPFLOW is suitable for appendage optimisation. An advantage with overlapping grids is that only the interpolations
between the grid
components, not the grids, needs to be updated when the appendages are repositioned. SHIPFLOW comes with parametised appendage objects that can be used directly or combined into more complex
appendages. Alternatively,
appendages can be modelled in Framework. Surface grids can then be
The Naval Architect January 2012
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