171 



STRIAnilM NO, 1 



STREAMLINE NO.l 



FIGURE 2. Body plans and potential 

 flow streamlines of models. 



pressure far upstream 

 pressure coefficient =(p-pa 



Pi(i=l,2,...) 



6 



61,62,611 



S21/9l2-922 



)/^ 



PUn 



91,92 

 K,B 



fo,fi 



0( 



asymptotic terms of normalized 

 pressure 



boundary layer thickness 

 three-dimensional boundary layer 

 thickness parameters defined by 

 Eqs. (5), (19) 



shape factor of streamwise velocity 

 profile =61/61 1 



angle between surface streamline 

 and external streamline direction, 

 positive in X2 direction 

 index for power-law velocity profile 

 parameter for wake part of wall-wake 

 law in qi , q2 components 

 coefficients of wall-wake law 

 wall and wake functions of wall- 

 wake law defined by Eq. (10) 

 resultant skin friction 

 components of skin friction in xi 

 and X2 directions 

 friction velocity 

 entrairanent function 

 parameter for separation 

 positions of onset of separation 

 and reattachment 



integral region for induced velocity 

 gradient vector 



symbol of orders f=0(e); lim -^ =M 

 (M: constant) 



1 ■ f 

 lun TT 



E->-0 



Static pressure measurements on hull surface 



Static pressure holes of 0.6mm were arranged on the 

 hull surface along streamlines and the static pres- 

 sure was measured by towing ahead and astern. 



Static pressure measurements in boundary layer 



Static pressure in the boundary layer was measured 

 by using a static pressure tube. It is 1.2mm in 

 diameter with two 0.4mm (fi holes on diametrically 

 opposite sides. A traverser with a micrometer was 

 used to move the probe normal to the hull surface. 

 The preliminary experiments showed that the static 

 pressure was free from incident flows whose attack 

 angles were less than 20°. 



Velocity measurements in boundary layer 



A total head probe, made from hypodermic tubing of 

 outside diameter 0.28mm and 2.7mm respectively, 

 was mounted on the traverser. Total pressure was 

 measured after locating flow directions by yawing 

 the directionally-sensitive hot film probe. Using 

 the measured static pressure, velocity was estimated 

 and decomposed into streamwise and crossflow 

 components . 



Local skin friction measurements 



2. EXPERIMENTAL STUDIES ON BOUNDARY LAYER 



Kinds of Experiments and Measuring Techniques 



In order to examine the boundary layer assumptions 

 and the validity of semi-empirical equations in 

 case of ship-like bodies, the following kinds of 

 experiments were carried out [Hatano et al . , (1978); 



Local skin friction on the hull surface was mea- 

 sured directly by a floating-element type friction 

 meter IHotta, (1975)]. The floating element is 14mm 

 in diameter with gaps of 0.05mm to the mounting case 

 and balanced by electromagnetic force . 



All experiments described above were carried out 

 using the GBT-125 under submerged conditions at a 

 depth of about 6 times the draft of the model. The 

 Reynolds number was kept constant at 10 . 



