F • CONVECTIVE HEAT TRANSFER IN GASES 



2.3 



Tw/Te 



Fig. F,19c. Effect of roughness on transition with cooling. 

 Me = 3.65. Wire trips at Re^ = 1.50 X lO^; 10° cone. 



Fig. F,19d. Effect of roughness on transition as a 

 function of Mach number. Zero heat transfer. 



boundary layer becomes sufficiently thin that the roughness shows its 

 effect. The fourth conclusion is again seen in Fig. F,19d, which is a cross- 

 plot of Fig. F,19a, F,19b, and F,19c for zero heat transfer. The ordinate 

 of Fig. F,19d is the ratio of the transition Reynolds number with a trip 

 Re^rj. to that for the smooth cone Re^^, whereas the abscissa is the ratio of 

 the roughness height k to the boundary layer displacement thickness 5* at 

 the trip, in accordance with the procedure of Dryden [58]. 



{ 404 ) 



