100 HYDRAULICS AND ITS APPLICATIONS 



(a) 100 j 



(b) 500 - gallons per minute. 



(c) 1,000) 

 N.B. 1 gallon = 10 Ibs. 



Answer, (a) Vel. = '340/. s. - '149 feet. 



(b) = 1-701 /. s. - 3-73 feet. 



(c) = 3-402 /. s. - 14-92 feet. 



(2) Inward radial flow takes place between two parallel circular plates, 

 3 feet diameter and 6 inches apart. Discharge takes place through an 

 orifice 18 inches diameter in the centre of the lower plate. Neglecting 

 viscous resistances, determine the pressure at the entrance when 1,000 

 cubic feet per minute pass the plates, assuming the pressure at the edge of 

 the discharge orifice to be atmospheric. 



Answer. -585 feet of water = -254 Ib. per square inch. 



(3) If in the previous example the plates are fitted with vanes and 

 rotate at 400 revolutions per minute, determine the difference of pressure 

 at inlet and outlet due solely to the production of a forced vortex. 



Answer. 46*04 feet of water = 20 Ibs. per square inch. 



(4) Taking the above (2) and (3), as an example of an inward radial 

 flow turbine, determine the total pressure drop between inlet and 

 outlet. 



Answer. 46 '62 feet of water. 



(5) A centrifugal pump has an impeller 12 inches internal, 24 inches 

 external diameter and runs at 800 revolutions, discharging into a vortex 

 chamber where a free vortex is formed. If the outer diameter of the 

 vortex chamber is 3 feet, determine the rise in pressure due to the vortex 

 motion 



(a) in the wheel ; (b) in the vortex chamber. 

 Neglect all losses and assume a perfectly efficient vortex chamber. 

 Answer, (a) 81 '9 feet of water. 

 (&) 60-6 



(6) A flat cylindrical disc, 18 inches diameter, keyed on to the lower 

 end of a 3 inch vertical shaft serves as a hydraulic footstep bearing. Its 

 lower face is plane and bears against radiating ribs cast in the pressure 

 cylinder, while its upper face carries a series of radial ribs which bear 

 against the plane upper lid of the pressure cylinder. Thus water above 

 the disc rotates with the disc, while the water below is at rest. The 

 upper and lower sides are in free communication around the periphery of 



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