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.

THE DELIVERY NOZZLE. 33 in a given time (assuming the water density tu remain con- stant), notwithstanding variations in the areas at tlie respective sections; that is to say, the velocity of the water jet multiplied by its cross-sectional area is a con- stant for all sections. It follows, therefore, that velocity and area vary inversely, and since the- area changes as the square of the diameters at the various sections, the velocity will change inversely as the square of ilie diameters. The velocity at any section of the delivery nozzle is obtained from the equation— Velocity in feet per second at any section volume in cubic feet passing per second area of section in square feet <7X2 Vi — ^22 = constant, (12 V v2=^.........................(xxii.) — diameter at nozzle inlet, — diameter at any section 2 of nozzle, — velocity at nozzle inlet, — velocity at any section 2 of nozzle. of formula (xxii.) a velocity curve can be plotted for any known form of nozzle if the velocity of the water jet aa it enters the nozzle is known. [f the diameter dx of, and also the velocity Vx at, the inlet end of the diverging nozzle are known, then the diameter d2, which corresponds with the velocity V2 at any section, is given by the following formula— or, since we may write where dx d2 and V2 tlie aid This formula enables a nozzle to be designed to give a known velocity curve for the jet passing therethrough. The pressures at any two sections of the diverging nozzle vary with the sqiiares of the velocities thereat. If the velocity Vj at the entranc© tc +he nozzle is known, and 4 si