The Steam Injector
A theoretical and practical treatise on the design and operation of injectors and on the flow of fluids through and the design of nozzles.

QUEST1ONS. 125 (7) Wliere does the greatest wear take place in an in- jector combining nozzle and what are the causes of such wear ? Describe and illustrate a form of combining nozzle which is particularly advantageous for use when wear is excessive. (8) How do you recommend that the jet delivered from the combining nozzle bo treated to obtain the greatest delivery pressure? Give a form ula showing the effect of any treatment you propose upon the velocity of said jet. (9) Draw an injector delivery nozzle of conical form of 3 in. lengtli having its smallest diameter one-lialf the largest, and give velocity and pressure eurves for said nozzle assuming the initial velocity to be 100 ft. per second and the initial pressure head of the jet to be zero. (10) Design an injector delivery nozzle to give a pressure curve such that the difference between the pressures at any hvo equidistant sections of tlie nozzle is the same. (11) What is the effect of employing a delivery nozzle with too rapid a taper? Wliere cloes the greatest wear of the delivery nozzle take place? Describe a methocl of minimising the effect of such wear upon the throat area of tlie nozzle. (12) The velocity of the jet at the throat of the delivery nozzle of an injector is 150 ft. per second, the diameter of the throat is "8 in., and the density of the jet at that point 59 Ibs. per cubic foot. How much water cloes the injector deliver per liour? If tlie- water entering the injector were cooled so that the. density of the delivery jet was increased to 60 Ibs. per cubic foot and the velocity to 160 ft. per second, what would be the increase in tlæ amount of water delivered per liour? (13) What provision would you make in an injector to make it a lifting appliance? What is meant by an auto- matic appliance? Describe three forms of automatic arrangements. (14) Discuss the variations of pressure in tlie combining nozzle at various points in its length, and describe a satis- factory arrangement of overflow apertures or the like which provide for automatic working of the injector.