FLYWHEEL EFFECT 567 



Applying the rule a = 2'4 = = '72 f.s.s., this gives us 



.*. A = 56'5 square feet, 

 corresponding to a diameter at the top of 8 '48 feet. 



The stand pipe would in this case take the form of a vertical pipe about 

 3 feet in diameter, and carrying a circular cistern 8 feet 6 inches in 

 diameter at the top, the top of this cistern being about 62 feet above the 

 centre line of the turbine and its depth about 3 feet 3 inches, thus 

 leaving a depth of water equal to 3 '25 2*0 '81 = *44 feet, when 

 working under full over-load. 



The stand pipe is not usually fitted where the supply head is above 

 200 feet. In the power plant of the St. Louis Hydro-Electric Company, 1 

 the total head is 380 feet, developed on a pipe line about 5,000 feet long. 

 When finally completed there are to be eight parallel pipes, each 7 feet 

 in diameter, coupled to a transverse receiver 500 feet back from the power 

 house, which receiver is itself at an elevation of 145 feet. From the 

 receiver, an open stand pipe 235 feet long and 6 feet diameter, carrying 

 at the top a circular tank 30 feet in diameter, is erected. 



The whole plant is intended to consist of eight units of 13,000 B.H.P. 

 each, the stand pipe being designed to supply sufficient energy for an 

 additional sudden demand of 10,000 B.H.P. 



In the Wenatchee Kiver Power Plant 2 three 4,000 K.W. Francis 

 turbines are supplied under a head of 200 feet through a pipe line 8*5 feet 

 diameter and 2'5 miles long. In this plant a surge pipe 8 feet diameter 

 is provided, the overflow level being 7 feet above the crest of the dam. 



ART. 153. FLYWHEEL EFFECT. 



So far, the effect of any flywheel which may be fitted to the turbine 

 shaft has been neglected, the rules already given applying where no 

 special flywheel is fitted. 



To consider the effect of such a wheel it must be remembered that 

 the total store of kinetic energy in a wheel of weight W Ibs. and of 

 effective radius r feet when rotating at a speed of o> radians per second 



/AT 27T^\ . 1 Wl* 2 



( N revolutions per minute, where w = \ , is equal to -5 - <* 

 foot Ibs. = g I <> 2 > where I = moment of inertia of wheel. If then 



1 The Engineer, February 15, 1907, p. 155. 



2 The Engineer, February 18, 1910, p. 166. 



