F • CONVECTIVE HEAT TRANSFER IN GASES 



The mean skin friction data of Sommer and Short [43] and Chapman 

 and Kester [44] are plotted in Fig. F,16b. The former data were obtained 

 from deceleration measurements of hollow cylinders in free flight, and 

 therefore the wall-to-free stream temperature ratio remained low (ranging 

 from 1.03 at Mach number 2.81 to 1.75 at Mach number 7). The latter 

 data were the result of steady state, direct total force measurements of 



1.0 



0.8 



Cf 



0.6 



0.4 



0.2 



10 



M. 



Fig. F,16a. Comparison of theory and experiment on local skin friction 

 coefficient for turbulent boundary layers on insulated fiat plates. 



the cyhnder of a cone-cylinder combination under zero heat transfer con- 

 ditions. The mean skin friction equation, viz. 



0.242 



AC}{T^/Te) 



T (sin~^ a + sin~^ /3) 



logiRe-Cf) -nlog^ (16-2) 



corresponding to Eq. 11-29, is also plotted in Fig. F,16b for n = 0.76. 

 It is readily apparent that Eq. 16-2 is verified and that the ruHng out of 

 Eq. 11-31 and 11-32 is justified. 



It will be noted (see Fig. F,16a) that the data of Coles show an effect 

 of Reynolds number as predicted by theory, whereas the data of Chap- 

 man and Kester yielded practically no effect of Reynolds number. 



Although the above data of Sommer and Short were gathered for 

 supersonic speeds, it should be pointed out that heat transfer effects on 

 skin friction can be studied at low speeds without a supersonic wind 



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