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The Proceedings Fifth International Conference on Numerical Ship Hydrodynamics (1990) / Chapter Skim
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Computation of a Nonlinear Rotational Inviscid Flow through a Heavily-Loaded Actuator Disk with a Large Hub
Pages 571-580

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From page 571...
... To estimate the effective wake from the nominal wake velocities measured in the propeller plane in absence of the propeller, several methods have been used. It was either estimated empirically by multiplying the measured circumferential mean nominal wake by a constant factor or determined theoretically.
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From page 572...
... Several axisymmetric approximations [4,51 draw attention to the importance of the shear flow effect on the propeller when treated as an actuator disk. Full investigation of the shear swirl flow interaction with the blade-induced velocity field and the secondary flow has not been undertaken so far in propeller theory.
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From page 573...
... In the present study, a sample calculation of ~ and pressure are rgade with the following form of the boundary conditions.
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From page 574...
... 1. Shear swirl flow field at U/(QR)
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From page 575...
... Along the contour Q the boundary conditions are given as where ~ = 0 on the hub r = rH or ~ = _ H The normal velocity on the hub is zero, or am = 0 at where t is the unit vector along the tangent to the hub.
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From page 576...
... Because of this complexity, there exists a line integral term, in addition to the area integral that was handled by Wu and Greenberg et al. The line integral includes the normal derivative of the unknown which changes the integral equation to an integro-differential equation.
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From page 577...
... The blade circulation given in the Table is converted by the relation zr ~ r00 = 2wlr taking the Goldstein factor K= 1 because for the 7-bladed propeller k is very close to 1. With this approximation, the thrust coefficient CTS, using the r values of Table 1, is very close to the measured value and the value from the lifting surface computation.
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From page 578...
... r curves are very close to each other. The efficiency computed with the boundary condition given by the measured longitudinal velocity at x= -0.480 IS 1.15 which is close to the value 1.17 from actuator disk theory.
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From page 579...
... Since experiments show that the propeller does not affect the flow beyond about two propeller diameters upstream [2] of the propeller the nominal wake at a station two propeller diameters upstream of the propeller plane may be effectively used to compute total flow using Equations (2)
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Key Terms

  • swirl flow
  • boundary conditions
  • shear swirl
  • line integral
  • shear flow

  • effective wake
  • stream function
  • governing equation
  • propeller plane
  • nominal wake

  • velocity components
  • iteration method
  • lifting surface
  • hub vortex
  • green function

  • trailing vortices
  • propeller performance
  • integral equation
  • secondary vorticity
  • axisymmetric flow

  • raphson method
  • propeller disk
  • disk theory
  • propeller blade
  • newton raphson

  • slip stream
  • secondary vortices
  • boundary condition
  • load distribution
  • ordinary differential


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