28 



f= ?r 



M 



Ux) 



'fL 



w 



[12] 



where £~ Is the decrement computed using Schoenherr coefficients, 

 C' f is the Schoenherr frictlonal coefficient, and 

 C„ T = 1.328 R " V2 is the Blasius laminar frictional coefficient. 



I Jj x 



As was to be expected, the agreement between Equations [8] and [12] is very 

 good. However, for the sake of consistency with present practice, values of 

 J determined from the Schoenherr coefficients will be used. The Schoenherr 

 coefficients are conveniently tabulated for various Reynolds numbers in a 

 Taylor Model Basin report. 12 



In a similar way a quantitative estimate of the effectiveness of the 

 various stimulating devices may be obtained by calculating the increase in the 

 frictional resistance of the model with turbulence stimulation over the fric- 

 tional resistance without any stimulation. This may be expressed in terms of 



8.0 10.0 12.0 



Modal Reynolds Number 



0.30 0.40 0.50 



Speed Length Ratio -=. 

 v L 



Figure 20 - Decrement of Frictional Resistance with no Stimulation 



