Model painted with white 

 lead prior to test 



Bow of Tanker with Typical Flow Trace from Lines of Flow Test 



Position of Second Tube or Socket 

 for Hot Wire Probe which Orients 

 Hot Wire Perpendicular to the Mean 

 Flow 



Mean 

 Streamline 



Tangent to Mean 

 Streamline 



Brass Tube Inserted 

 Flush to Hull Surface 

 0.060" 0.0. 0.035" l.D. 



Lead Sulphide Stain 



Enlargement of Hull Surface at Point where Hydrogen Sulphide 

 is Ejected at a Fixed Towing Speed 



Figure 4 



Technique Used for Orientation of Hot Wire at 

 Selected Positions on Tanker Model 



Classification of the flow at a probe is accomplished by interpret- 

 ing the signal obtained from the probe. Typical "signatures" of laminar, 

 transitional, and turbulent flow are shown in Figure 7- It may be seen that 

 transition extends over a range of speeds, or more properly, of Reynolds num- 

 bers. These are based on a length measured from the bow along the half-draft 

 water line to the start of the transition region. Furthermore, the occurrence 

 of the turbulent bursts within the transitional range steadily increases until 

 the flow becomes completely turbulent. There is another flow condition which 

 for brevity has been omitted in Figure 7 and is represented in detail in Fig- 

 ure 8. This flow is laminar with low-frequency oscillations and is similar to 

 the "laminar oscillations" observed in the boundary layer of a flat plate by 

 Schubauer and Skramstad 3 except that the oscillations in Figure 8 are much 

 more random than those reported in the earlier investigation. These laminar 

 oscillations grow in magnitude and increase in frequency with increase in 

 speed at a given point in the boundary layer until turbulent bursts occur. 



