cell, for the model scale transition is specified at a fixed percentage of the blade chord.

The accuracy of boundary layer flow can in part be obtained from the comparison of predicted and measured wake flow variables. The comparisons suggested would be useful but at the present time these have not been undertaken.

Although the 3-bladed propeller has a simple geometry the flow over the blade surface is far from simple and the author questions the validity of a comparison with 2-dimensional flow as suggested by Dr. Uto.

The propulsion coefficients are made up from two components, one pressure, the other wall shear stress. The pressure term also includes the influence of viscosity due to the boundary layer thickness resulting in blade to blade blockage, one of the effects of the viscous boundary layer. For completeness a comparison with Euler and potential calculations may give a better indication of the effect of viscosity. The following tables give a breakdown of the two components and have been non-dimensionalized using the resultant component obtained from the RANS code.

Pressure and Blade Surface Viscous Forces

Propeller

J

δΚΤpT

δΚT

δΚQp/KQ

δΚ/KQ

Size

dtrc4119

0.84

1.015

−0.015

0.897

0.103

model

dtrc4119

0.50

1.006

−0.006

0.956

0.044

model

dtrc4119

1.13

1.148

−0.148

0.692

0.308

model

dtrc4119

0.84

1.013

−0.0.13

0.906

0.094

full

dtrc4119

0.5

1.004

−0.004

0.961

0.039

full

dtrc4119

1.12

1.088

−0.088

0.722

0.278

full

C660

1.012

−0.012

0.911

0.089

model

C660

1.012

−0.012

0.910

0.090

full

RANS and Euler Predictions

Propeller

J

(KT)EULER/(KT)RANS

(KQ)EULER/(KQ)RANS

Size

dtrc4119

0.84

1.066

0.925

model

dtrc4119

0.50

1.029

0.967

model

dtrc4119

1.13

1.644

0.761

model

dtrc4119

0.84

1.056

0.935

full

dtrc4119

0.5

1.001

0.948

full

dtrc4119

1.12

1.259

0.792

full

C660

1.170

1.032

model

C660

1.145

1.016

full



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