COMPOUNDING OF JETS 



383 



AET. 110. COMPOUNDING OF JETS. 



If two steady streams are allowed to impinge on each other under 

 atmospheric pressure, they com- 

 bine to form a single stream. 



Let streams (1) and (2) com- 

 bine to form stream (3) (Fig. 

 173). Then if a, v, and Q represent 

 the sectional areas, velocities of 

 flow, and quantity carried by each 

 stream, we have, if 6 be the angle 

 made by an impinging stream with the direction of the resultant stream : 



For continuity of flow, T\, a\ -f- *"2, a> 2 , = r 3 , a 3 (1) 



The equations of momentum give : 



Qi Vi sin #1 $2 v% sin 2 = (2) 



Qi TI cos 0i -\- Q 2 r 2 cos 02 = Qz i's (3) 



while the equation of energy gives : 



FIG. 173. 







2 cf 



(o> 



*-+H' 



vf 



(4) 



By substitution from equations (2) and (3) above, this loss may be 

 determined in terms of v^ r^, 

 Q\ and 6%. 



In two particular cases //' 

 may 'be zero. In each of 

 these it is necessary that 



1 3 ~~ 





simultaneous- 



+ i'i 



ly, and therefore that 



__ i B t | 



The first case is found 

 where Vi = v% = ?; 3 , i.e., where 

 two parallel streams moving FlG J m 



with the same velocity com- 

 bine to form a single stream, with an area equal to the combined area of 

 the two. The second case is found where i'i = v^ each of these being 



