10 

 0-8 



06 



V-0 



04 



02 



20° 40° 60° 80° 100° 120° 140° 160° 180* 



03 



Figure 13. Variation of drag coefficient with cone angle. (Q = 0) 



Clayden (1956) have recently investigated the two dimensional flow near a wedge of 

 30 degs. semi-angle at small angles of incidence at zero cavitation number. In this 

 particular example, incidence produced a movement of the stagnation point on to the 

 face of the wedge which was most inclined to the main flow; a subsidiary cavity was 

 also formed on the leeward face at the apex of the wedge. Fig. 14 is a photograph of 

 this wedge at 10 degs. incidence obtained in the A.R.D.E. cavitation tunnel. Fig. 15 

 is a diagrammatic representation of the mathematical model which was used in a 

 theoretical investigation of the problem when the flow in the neighbourhood of the 

 subsidiary cavity was treated according to the Gilbarg re-entrant jet technique. 

 Analytical expressions were obtained for the lift-slope and moment-slope coefficients 

 for small angles of yaw. Fig. 16 gives a comparison of the theoretical value of 



for different wedges with recent measurements made in the A.R.D.E. 



a Ja ~^ 



cavitation tunnel. 



The above example shows clearly some of the additional complexities which 

 arise when an attempt is made to investigate by exact theory the conditions near a 

 yawed cone, or similar body. In spite of these difficulties it is of interest to explore 

 this problem by means of much simplified models and techniques, such as the applica- 

 tion of a. principles of similitude or b. a modified Munk-Jones cross-flow theory. Both 

 these techniques have been under investigation at Fort Halstead. 



In applying the similitude technique we use a simplified "Strip Theory" with 

 a two dimensional wedge model having the stagnation point at the nose rather than 

 the model with the subsidiary cavity described above. This is probably justifiable 

 because of the extra degree of freedom in the flow past the cone. Thus we imagine a 

 wedge AOB, of semi-angle /?, at a small angle of yaw S to the stream, we assume that 



