F • CONVECTIVE HEAT TRANSFER IN GASES 



technique, first used by the Germans in the V-2 rocket motor, by which 

 small quantities of fluid, say the regenerative coolant, are permitted to 

 enter the nozzle at many points on the interior surface and spread over 

 the wall in a thin film. When the coolant is introduced in the nozzle 

 through the porous wall, the process is called sweat cooling. 



Rocket motor 



.b 3 



3 

 h- 

 CQ 



O 

 CD 



I 



12 



16 



20 



Motor length, in. 



Fig. F,21a. Heat transfer distribution in acid-aniline rocket motor. 



Experimental investigations. Because of the large variation of flow 

 properties within the rocket nozzle, theoretical calculation of heat trans- 

 fer in rocket motors has given way to experiment. 



A rather complete experimental investigation has been carried out by 

 Boden [67] to determine the effect of many factors, including film cooling, 

 on the heat transfer in a 1000-lb thrust rocket motor using 6^ per cent 

 red fuming nitric acid for the oxidizer and a mixed fuel of 80 per cent 

 aniline and 20 per cent furfuryl alcohol. The combustion-chamber tem- 

 perature was about 5000°F. The rate of heat transfer was obtained at 

 various sections of the motor, including the combustion chamber, by 



(416) 



