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Previous: Running blockMesh Up: Creating computational mesh using Next: Computation set-up

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Viewing the mesh

  • Run command paraFoam to view the mesh (runs ParaView with special options)
    # cd $FOAM_RUN /pitzDaily
    # paraFoam
openfoam tutorial backward facing step pitzDaily mesh

Figure: Backward-Facing-Step tutorial, computational mesh

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Next: Message Passing Interface (MPI) Up: TCFDSRTSolver – compressible, transient, Previous: Turbulent Flow   Contents   Index

MRF (Multiple Reference Frame) Method for Rotation of Rotating Parts

For simulating of the rotation it is used Multiple Reference Frame (MRF) method. MRF adds source term (acceleration) to velocity (momentum) equations. Source term is applied on volume cells cellZone. For more details see e.g. [10].

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Previous: Wind Turbine Efficiency Up: Formulas for the Efficiency Next: Stator Efficiency
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Propeller Efficiency

There are two quantities of interest for propeller:

  • Thrust – $ T$ [N]
  • Torque – $ M$ [N$ \cdot$m]

In case of propeller, reference pressure is not taken into account when evaluating thrust and torque.

Dimensional analysis leads to a definition of propeller coefficients representing its performance. 8.1

  • Torque coefficient ($ k_Q$):
    $\displaystyle k_Q = \frac{M}{\rho n^2 D^5}\,,$(8.9)

     

  • Thrust coefficient ($ k_T$):
    $\displaystyle k_T = \frac{T}{\rho n^2 D^4}\,,$(8.10)

     

where $ n$ is the propeller speed [rev/s] and $ D$ denotes the propeller diamater [m].

The efficiency can be evaluated using the supplied power to the propeller ( $ P_\mathrm{in}$) and the useful power output ( $ P_\mathrm{out}$):

$\displaystyle \eta^{propeller} = \frac{P_\mathrm{out}}{P_\mathrm{in}} = \frac{TU_0}{2\pi n M} = \frac{1}{2\pi} \frac{k_T}{k_Q} J\,,$(8.11)

where $ J$ is the advance ratio and is given as the distance advanced by the propeller in one revolution divided by the propeller diameter, i.e., $ J=U_0/(Dn)\,$.

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Previous: Wind Turbine Efficiency Up: Formulas for the Efficiency Next: Stator Efficiency

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