CFD & FEA: Introduction | CFD (details) | FEA (details)

Flow Simulation Services: CFD – Hydrodynamic Engineering. Some projects, such as, the removal of cavitation generated by a ship rudder include the use of both inviscid and viscous CFD codes.
Inviscid flow projects include:

  • Propeller modelling
  • Rudder modelling
  • Cavitation modelling

Viscous flow projects include:

  • Rudder and propeller interaction with or without the ship afterbody
  • Smoke and ventilation studies
  • Ship response in adverse sea conditions
  • Explicit modelling of cavitation
  • Wake field calculation for inviscid flow projects
  • Pressure field calculation to provide boundary conditions for FEA

Inviscid Flow Modelling on a Propeller: BEM represents a straight forward and rapid method for determining the characteristics of a propeller.

  • Transient analysis
  • Rotational symmetry in the model
  • From the time domain to the frequency domain

Steady State Rudder Modelling using RANS: This is a straight forward analysis with the propeller modelled by an actuator disk. From the calculation we obtain:

  • The drag, lift and torque on the rudder
  • The pressure field for export to FEA as a boundary condition
  • An understanding of the flow field around the rudder
  • A clear warning about the risk of cavitation generated by the rudder
  • The wake field for use in the BEM code

Cavitation Modelling on Rudders and Propellers: Cavitation modelling for rudders involves making subtle design changes to remove the risk of cavitation. The aim is to design a rudder that does not generate cavitation. At ibmv we run the BEM code in:

  • Steady state mode
  • Wake field taken from the RANS code
  • Calculate σy
  • Co-ordinate adjustments made either automatically or interactively to the rudder to ensure σy>0.

Explicit Modelling of Propeller Cavitation: Transient RANS calculation to accurately capture propeller hub and blade cavitation. The example shown includes periodic hub cavitation and the variation of cavitation wth depth. The geometry is a tanker propeller.

Pictures above showing a propeller
and the frequency domain.

Cavitation generated by both the blades and the hub on a full scale propeller model.

Calculation performed on a ship hull model.

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