THEORY OF TURBINE DESIGN 541 



H 2 X 60 



7), Revolutions = s - per minute. 



2 TT r 2 



RADIAL INWARD FLOW TURBINE WITH RADIAL VANE TIPS. 

 In practice the vanes are very commonly made radial at the tips. In 

 his case, putting /3 = 90, tan /3 = a , we now have, for no shock at 

 sntrance, the velocity of whirl iv 2 equal to the peripheral velocity u% of the 

 vheel. Making these substitutions in the general expressions already 

 >btained we get : 



= M'2 = A / 



a feet P er second. 



;2) 6 / 2 = H'a tan a feet per second. 



2 - 



3)," tan y = n 2 , - tan a 



'4) b f 3 = n^ fa feet per second. 



cosec 

 Ibs. per square foot. 



( n j- tan a ) 

 V . Og ' 



In some cases the velocity of flow is kept constant by increasing the 

 breadth of the turbine as the radius diminishes so as to keep b r constant. 



[n this case / 2 = / 3 , 6 2 ?* 2 = &a ?'a, and therefore ?i ^ = 1, and the 



^3 



foregoing results are modified as follows : 



A / 2 cj W 

 a = ?r 2 =: V 2 + tan 2^ f ee t per second. 



(3)' tan 7 = n tan a 



(4)' / 3 =/ 2 feet per second. 



(5)' p = P2 - 9 f W | 1 - ( - ) 2 | + / 2 2 (cosec *B - 1) 1 

 * 9 L \ W J -I 



Ibs. per square foot. 



" = '2+L^ 



Since a is always small, the peripheral velocity of the wheel for 

 maximum velocity is very approximately given (1)' by 



A/ 2?#' 



= * - v -%- = 



