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.

34 THE STEAM INJECTOR. also the velocity V2 at any section 2 of the same, then thø difference between the squares of these velocities plus the fluid head H1 at the entrance to the nozzle represents the head at section 2. That is, Head at section 2 * 2 V 2 * 11_____Il + Hr..................(xxiv.) 2<7 or, as head in feet pressure in pounds per square foot weight per cubic foot we may write * 2 = VL - Vf + Pi. iv 2 g w If we take pressure in pounds per square inch head in feet 2-3 ’ then p2, or pressure at- section 2 _ V? - V/ + Hj 2 ry x 2-3 2-3 (xxv.) The pressure of the jet at the entrance to the diverging delivery nozzle varies with the temperature of the jet. As the mixing of the steam and water is assumed to be com- pleted in the combining nozzle, the temperature of the jet entering the delivery nozzle may be taken as the same as that of the water delivered from the injector. The diagram, fig. 17, shows the diverging portion of an injector delivery nozzle so proportioned as to cause a uniform retardation in the motion of a jet passing tliere- through; that is to say, the difference between the velocities of the jet at any two equidistant sections is the same. A velocity curve for an initial velocity of 200 ft. per second, and the corresponding pressure curve (the initial pressure being for convenience considered as zero), are plotted at the upper portion of the figure.