10 



TM8 MODEL 4083 

 MODEL OF 612-FX 33.950-TON TANKER 

 LINEAR RATIO 24. MODEL LENGTH 255 FT 

 EQUIPPED WITH HOT-WIRE PROBES 



FOR BOUNDARY LAYER SURVEY 



FRICTIONAL RESISTANCE RESEARCH 



NS 715-DS2 



>.Sl 



■'*&■' 



TMB 41461 



Figure 6 - TMB Model 4083 Showing Distribution of Hot-Wire Probes 

 with Insert Enlargement of 4 Probes 



the model showed turbulent flow. The second check consisted of moving a hot- 

 wire probe in and out of the boundary layer by means of a micrometer screw. 

 When the wire was within 0.3-inch of the surface the response of the wire was 

 characteristic of turbulence. The intensity of turbulence decays toward the 

 "edge" of the layer and beyond this the flow was found to be without 

 fluctuation. 



TEST CONDITIONS 



Surveys of the boundary-layer flow were made under four conditions. 

 For the first condition the model was towed without any turbulence stimulator. 

 For the second, a series of tests were conducted in which a 1 /8-inch rod, held 

 vertically in the water, was placed successively at 24, 48, and 192 diameters 

 forward of the model stem, i.e., at 3 in., 6 in., and 24 in., respectively. 

 For the third condition, records -of the boundary-layer flow aft of a 0.032- 

 inch trip wire, tacked around the girth of the model, were obtained. Finally, 

 similar measurements were made with a fine-grain sand strip, 7/8-inch wide, 

 in place of the trip wire . Location of these stimulators and their pertinent 

 dimensions are given in Figure 9. For each of these conditions of stimulation 

 the model was ballasted to correspond to the ship displacement of 33,950 tons 

 of sea water at zero trim. The model was towed at 15 speeds in the range be- 

 tween 0.4 and 3. 50 knots corresponding to 1-96 and 17-15 knots for the ship. 



