F • CONVECTIVE HEAT TRANSFER IN GASES 



resulting from the absorption of energy in the breaking apart of the air 

 components. 



Properties of Dissociated Air. Before any calculation of heat 

 transfer under conditions conducive to dissociation can be undertaken, 

 the thermodynamic, as well as transport, properties must be determined. 

 For example. Fig. F,22a and F,22b give the variation of enthalpy [69] 

 and viscosity [70], respectively, of dissociated and undissociated air for 



20 



24 



12 16 



Mach number M«, 



Fig. F,22f. Ratio of stagnation to ambient pressure across a normal shock for air. 



various pressures. The Prandtl number, however, is not altered appreci- 

 ably by high temperature, as indicated in Fig. F,22c [71]. 



Calculation of Heat Transfer near the Stagnation Point 

 including Dissociation. 



Laminar flow. As mentioned in Art. 7, the results expressed in Eq. 

 7-lb, 7-2b, and 7-3b for laminar flow heat transfer at the stagnation point 

 of a body at supersonic speed can be applied with some approximation 

 to hypersonic flow. 



In Eq. 7-2b and 7-3b, /3 is again obtained from Fig. F,7a. The Prandtl 

 number {Cpn/ky is taken from Fig. F,22c where it is seen to remain at a 

 value of about 0.7 for air. The density ratio pVp=o value of about 0.7 for 



< 422 ) 



